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Commit 53c8f9f199b239668e6b1a907735ee323a0d1ccd

Authored by Oleg Nesterov 2011-06-23 05:08:18 +0800

Exists in master and in 6 other branches

make do_notify_parent() return bool

- change do_notify_parent() to return a boolean, true if the task should
  be reaped because its parent ignores SIGCHLD.

- update the only caller which checks the returned value, exit_notify().

This temporary uglifies exit_notify() even more, will be cleanuped by
the next change.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>

Showing 3 changed files with 17 additions and 13 deletions Inline Diff

include/linux/sched.h
kernel/exit.c
kernel/signal.c

include/linux/sched.h

Diff comments View file @ 53c8f9f

kernel/exit.c

Diff comments View file @ 53c8f9f

 /*
  *  linux/kernel/exit.c
  *
  *  Copyright (C) 1991, 1992  Linus Torvalds
  */
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/capability.h>
 #include <linux/completion.h>
 #include <linux/personality.h>
 #include <linux/tty.h>
 #include <linux/iocontext.h>
 #include <linux/key.h>
 #include <linux/security.h>
 #include <linux/cpu.h>
 #include <linux/acct.h>
 #include <linux/tsacct_kern.h>
 #include <linux/file.h>
 #include <linux/fdtable.h>
 #include <linux/binfmts.h>
 #include <linux/nsproxy.h>
 #include <linux/pid_namespace.h>
 #include <linux/ptrace.h>
 #include <linux/profile.h>
 #include <linux/mount.h>
 #include <linux/proc_fs.h>
 #include <linux/kthread.h>
 #include <linux/mempolicy.h>
 #include <linux/taskstats_kern.h>
 #include <linux/delayacct.h>
 #include <linux/freezer.h>
 #include <linux/cgroup.h>
 #include <linux/syscalls.h>
 #include <linux/signal.h>
 #include <linux/posix-timers.h>
 #include <linux/cn_proc.h>
 #include <linux/mutex.h>
 #include <linux/futex.h>
 #include <linux/pipe_fs_i.h>
 #include <linux/audit.h> /* for audit_free() */
 #include <linux/resource.h>
 #include <linux/blkdev.h>
 #include <linux/task_io_accounting_ops.h>
 #include <linux/tracehook.h>
 #include <linux/fs_struct.h>
 #include <linux/init_task.h>
 #include <linux/perf_event.h>
 #include <trace/events/sched.h>
 #include <linux/hw_breakpoint.h>
 #include <linux/oom.h>
 #include <asm/uaccess.h>
 #include <asm/unistd.h>
 #include <asm/pgtable.h>
 #include <asm/mmu_context.h>
 static void exit_mm(struct task_struct * tsk);
 static void __unhash_process(struct task_struct *p, bool group_dead)
 {
 	nr_threads--;
 	detach_pid(p, PIDTYPE_PID);
 	if (group_dead) {
 		detach_pid(p, PIDTYPE_PGID);
 		detach_pid(p, PIDTYPE_SID);
 		list_del_rcu(&p->tasks);
 		list_del_init(&p->sibling);
 		__this_cpu_dec(process_counts);
 	}
 	list_del_rcu(&p->thread_group);
 }
 /*
  * This function expects the tasklist_lock write-locked.
  */
 static void __exit_signal(struct task_struct *tsk)
 {
 	struct signal_struct *sig = tsk->signal;
 	bool group_dead = thread_group_leader(tsk);
 	struct sighand_struct *sighand;
 	struct tty_struct *uninitialized_var(tty);
 	sighand = rcu_dereference_check(tsk->sighand,
 					rcu_read_lock_held() ||
 					lockdep_tasklist_lock_is_held());
 	spin_lock(&sighand->siglock);
 	posix_cpu_timers_exit(tsk);
 	if (group_dead) {
 		posix_cpu_timers_exit_group(tsk);
 		tty = sig->tty;
 		sig->tty = NULL;
 	} else {
 		/*
 		 * This can only happen if the caller is de_thread().
 		 * FIXME: this is the temporary hack, we should teach
 		 * posix-cpu-timers to handle this case correctly.
 		 */
 		if (unlikely(has_group_leader_pid(tsk)))
 			posix_cpu_timers_exit_group(tsk);
 		/*
 		 * If there is any task waiting for the group exit
 		 * then notify it:
 		 */
 		if (sig->notify_count > 0 && !--sig->notify_count)
 			wake_up_process(sig->group_exit_task);
 		if (tsk == sig->curr_target)
 			sig->curr_target = next_thread(tsk);
 		/*
 		 * Accumulate here the counters for all threads but the
 		 * group leader as they die, so they can be added into
 		 * the process-wide totals when those are taken.
 		 * The group leader stays around as a zombie as long
 		 * as there are other threads.  When it gets reaped,
 		 * the exit.c code will add its counts into these totals.
 		 * We won't ever get here for the group leader, since it
 		 * will have been the last reference on the signal_struct.
 		 */
 		sig->utime = cputime_add(sig->utime, tsk->utime);
 		sig->stime = cputime_add(sig->stime, tsk->stime);
 		sig->gtime = cputime_add(sig->gtime, tsk->gtime);
 		sig->min_flt += tsk->min_flt;
 		sig->maj_flt += tsk->maj_flt;
 		sig->nvcsw += tsk->nvcsw;
 		sig->nivcsw += tsk->nivcsw;
 		sig->inblock += task_io_get_inblock(tsk);
 		sig->oublock += task_io_get_oublock(tsk);
 		task_io_accounting_add(&sig->ioac, &tsk->ioac);
 		sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
 	}
 	sig->nr_threads--;
 	__unhash_process(tsk, group_dead);
 	/*
 	 * Do this under ->siglock, we can race with another thread
 	 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
 	 */
 	flush_sigqueue(&tsk->pending);
 	tsk->sighand = NULL;
 	spin_unlock(&sighand->siglock);
 	__cleanup_sighand(sighand);
 	clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
 	if (group_dead) {
 		flush_sigqueue(&sig->shared_pending);
 		tty_kref_put(tty);
 	}
 }
 static void delayed_put_task_struct(struct rcu_head *rhp)
 {
 	struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
 	perf_event_delayed_put(tsk);
 	trace_sched_process_free(tsk);
 	put_task_struct(tsk);
 }
 void release_task(struct task_struct * p)
 {
 	struct task_struct *leader;
 	int zap_leader;
 repeat:
 	/* don't need to get the RCU readlock here - the process is dead and
 	 * can't be modifying its own credentials. But shut RCU-lockdep up */
 	rcu_read_lock();
 	atomic_dec(&__task_cred(p)->user->processes);
 	rcu_read_unlock();
 	proc_flush_task(p);
 	write_lock_irq(&tasklist_lock);
 	ptrace_release_task(p);
 	__exit_signal(p);
 	/*
 	 * If we are the last non-leader member of the thread
 	 * group, and the leader is zombie, then notify the
 	 * group leader's parent process. (if it wants notification.)
 	 */
 	zap_leader = 0;
 	leader = p->group_leader;
 	if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
 		BUG_ON(task_detached(leader));
 		do_notify_parent(leader, leader->exit_signal);
 		/*
 		 * If we were the last child thread and the leader has
 		 * exited already, and the leader's parent ignores SIGCHLD,
 		 * then we are the one who should release the leader.
 		 *
 		 * do_notify_parent() will have marked it self-reaping in
 		 * that case.
 		 */
 		zap_leader = task_detached(leader);
 		/*
 		 * This maintains the invariant that release_task()
 		 * only runs on a task in EXIT_DEAD, just for sanity.
 		 */
 		if (zap_leader)
 			leader->exit_state = EXIT_DEAD;
 	}
 	write_unlock_irq(&tasklist_lock);
 	release_thread(p);
 	call_rcu(&p->rcu, delayed_put_task_struct);
 	p = leader;
 	if (unlikely(zap_leader))
 		goto repeat;
 }
 /*
  * This checks not only the pgrp, but falls back on the pid if no
  * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
  * without this...
  *
  * The caller must hold rcu lock or the tasklist lock.
  */
 struct pid *session_of_pgrp(struct pid *pgrp)
 {
 	struct task_struct *p;
 	struct pid *sid = NULL;
 	p = pid_task(pgrp, PIDTYPE_PGID);
 	if (p == NULL)
 		p = pid_task(pgrp, PIDTYPE_PID);
 	if (p != NULL)
 		sid = task_session(p);
 	return sid;
 }
 /*
  * Determine if a process group is "orphaned", according to the POSIX
  * definition in 2.2.2.52.  Orphaned process groups are not to be affected
  * by terminal-generated stop signals.  Newly orphaned process groups are
  * to receive a SIGHUP and a SIGCONT.
  *
  * "I ask you, have you ever known what it is to be an orphan?"
  */
 static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task)
 {
 	struct task_struct *p;
 	do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
 		if ((p == ignored_task) ||
 		    (p->exit_state && thread_group_empty(p)) ||
 		    is_global_init(p->real_parent))
 			continue;
 		if (task_pgrp(p->real_parent) != pgrp &&
 		    task_session(p->real_parent) == task_session(p))
 			return 0;
 	} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
 	return 1;
 }
 int is_current_pgrp_orphaned(void)
 {
 	int retval;
 	read_lock(&tasklist_lock);
 	retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
 	read_unlock(&tasklist_lock);
 	return retval;
 }
 static int has_stopped_jobs(struct pid *pgrp)
 {
 	int retval = 0;
 	struct task_struct *p;
 	do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
 		if (!task_is_stopped(p))
 			continue;
 		retval = 1;
 		break;
 	} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
 	return retval;
 }
 /*
  * Check to see if any process groups have become orphaned as
  * a result of our exiting, and if they have any stopped jobs,
  * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
  */
 static void
 kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
 {
 	struct pid *pgrp = task_pgrp(tsk);
 	struct task_struct *ignored_task = tsk;
 	if (!parent)
 		 /* exit: our father is in a different pgrp than
 		  * we are and we were the only connection outside.
 		  */
 		parent = tsk->real_parent;
 	else
 		/* reparent: our child is in a different pgrp than
 		 * we are, and it was the only connection outside.
 		 */
 		ignored_task = NULL;
 	if (task_pgrp(parent) != pgrp &&
 	    task_session(parent) == task_session(tsk) &&
 	    will_become_orphaned_pgrp(pgrp, ignored_task) &&
 	    has_stopped_jobs(pgrp)) {
 		__kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
 		__kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
 	}
 }
 /**
  * reparent_to_kthreadd - Reparent the calling kernel thread to kthreadd
  *
  * If a kernel thread is launched as a result of a system call, or if
  * it ever exits, it should generally reparent itself to kthreadd so it
  * isn't in the way of other processes and is correctly cleaned up on exit.
  *
  * The various task state such as scheduling policy and priority may have
  * been inherited from a user process, so we reset them to sane values here.
  *
  * NOTE that reparent_to_kthreadd() gives the caller full capabilities.
  */
 static void reparent_to_kthreadd(void)
 {
 	write_lock_irq(&tasklist_lock);
 	ptrace_unlink(current);
 	/* Reparent to init */
 	current->real_parent = current->parent = kthreadd_task;
 	list_move_tail(&current->sibling, &current->real_parent->children);
 	/* Set the exit signal to SIGCHLD so we signal init on exit */
 	current->exit_signal = SIGCHLD;
 	if (task_nice(current) < 0)
 		set_user_nice(current, 0);
 	/* cpus_allowed? */
 	/* rt_priority? */
 	/* signals? */
 	memcpy(current->signal->rlim, init_task.signal->rlim,
 	       sizeof(current->signal->rlim));
 	atomic_inc(&init_cred.usage);
 	commit_creds(&init_cred);
 	write_unlock_irq(&tasklist_lock);
 }
 void __set_special_pids(struct pid *pid)
 {
 	struct task_struct *curr = current->group_leader;
 	if (task_session(curr) != pid)
 		change_pid(curr, PIDTYPE_SID, pid);
 	if (task_pgrp(curr) != pid)
 		change_pid(curr, PIDTYPE_PGID, pid);
 }
 static void set_special_pids(struct pid *pid)
 {
 	write_lock_irq(&tasklist_lock);
 	__set_special_pids(pid);
 	write_unlock_irq(&tasklist_lock);
 }
 /*
  * Let kernel threads use this to say that they allow a certain signal.
  * Must not be used if kthread was cloned with CLONE_SIGHAND.
  */
 int allow_signal(int sig)
 {
 	if (!valid_signal(sig) || sig < 1)
 		return -EINVAL;
 	spin_lock_irq(&current->sighand->siglock);
 	/* This is only needed for daemonize()'ed kthreads */
 	sigdelset(&current->blocked, sig);
 	/*
 	 * Kernel threads handle their own signals. Let the signal code
 	 * know it'll be handled, so that they don't get converted to
 	 * SIGKILL or just silently dropped.
 	 */
 	current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
 	return 0;
 }
 EXPORT_SYMBOL(allow_signal);
 int disallow_signal(int sig)
 {
 	if (!valid_signal(sig) || sig < 1)
 		return -EINVAL;
 	spin_lock_irq(&current->sighand->siglock);
 	current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN;
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
 	return 0;
 }
 EXPORT_SYMBOL(disallow_signal);
 /*
  *	Put all the gunge required to become a kernel thread without
  *	attached user resources in one place where it belongs.
  */
 void daemonize(const char *name, ...)
 {
 	va_list args;
 	sigset_t blocked;
 	va_start(args, name);
 	vsnprintf(current->comm, sizeof(current->comm), name, args);
 	va_end(args);
 	/*
 	 * If we were started as result of loading a module, close all of the
 	 * user space pages.  We don't need them, and if we didn't close them
 	 * they would be locked into memory.
 	 */
 	exit_mm(current);
 	/*
 	 * We don't want to have TIF_FREEZE set if the system-wide hibernation
 	 * or suspend transition begins right now.
 	 */
 	current->flags |= (PF_NOFREEZE | PF_KTHREAD);
 	if (current->nsproxy != &init_nsproxy) {
 		get_nsproxy(&init_nsproxy);
 		switch_task_namespaces(current, &init_nsproxy);
 	}
 	set_special_pids(&init_struct_pid);
 	proc_clear_tty(current);
 	/* Block and flush all signals */
 	sigfillset(&blocked);
 	sigprocmask(SIG_BLOCK, &blocked, NULL);
 	flush_signals(current);
 	/* Become as one with the init task */
 	daemonize_fs_struct();
 	exit_files(current);
 	current->files = init_task.files;
 	atomic_inc(&current->files->count);
 	reparent_to_kthreadd();
 }
 EXPORT_SYMBOL(daemonize);
 static void close_files(struct files_struct * files)
 {
 	int i, j;
 	struct fdtable *fdt;
 	j = 0;
 	/*
 	 * It is safe to dereference the fd table without RCU or
 	 * ->file_lock because this is the last reference to the
 	 * files structure.  But use RCU to shut RCU-lockdep up.
 	 */
 	rcu_read_lock();
 	fdt = files_fdtable(files);
 	rcu_read_unlock();
 	for (;;) {
 		unsigned long set;
 		i = j * __NFDBITS;
 		if (i >= fdt->max_fds)
 			break;
 		set = fdt->open_fds->fds_bits[j++];
 		while (set) {
 			if (set & 1) {
 				struct file * file = xchg(&fdt->fd[i], NULL);
 				if (file) {
 					filp_close(file, files);
 					cond_resched();
 				}
 			}
 			i++;
 			set >>= 1;
 		}
 	}
 }
 struct files_struct *get_files_struct(struct task_struct *task)
 {
 	struct files_struct *files;
 	task_lock(task);
 	files = task->files;
 	if (files)
 		atomic_inc(&files->count);
 	task_unlock(task);
 	return files;
 }
 void put_files_struct(struct files_struct *files)
 {
 	struct fdtable *fdt;
 	if (atomic_dec_and_test(&files->count)) {
 		close_files(files);
 		/*
 		 * Free the fd and fdset arrays if we expanded them.
 		 * If the fdtable was embedded, pass files for freeing
 		 * at the end of the RCU grace period. Otherwise,
 		 * you can free files immediately.
 		 */
 		rcu_read_lock();
 		fdt = files_fdtable(files);
 		if (fdt != &files->fdtab)
 			kmem_cache_free(files_cachep, files);
 		free_fdtable(fdt);
 		rcu_read_unlock();
 	}
 }
 void reset_files_struct(struct files_struct *files)
 {
 	struct task_struct *tsk = current;
 	struct files_struct *old;
 	old = tsk->files;
 	task_lock(tsk);
 	tsk->files = files;
 	task_unlock(tsk);
 	put_files_struct(old);
 }
 void exit_files(struct task_struct *tsk)
 {
 	struct files_struct * files = tsk->files;
 	if (files) {
 		task_lock(tsk);
 		tsk->files = NULL;
 		task_unlock(tsk);
 		put_files_struct(files);
 	}
 }
 #ifdef CONFIG_MM_OWNER
 /*
  * Task p is exiting and it owned mm, lets find a new owner for it
  */
 static inline int
 mm_need_new_owner(struct mm_struct *mm, struct task_struct *p)
 {
 	/*
 	 * If there are other users of the mm and the owner (us) is exiting
 	 * we need to find a new owner to take on the responsibility.
 	 */
 	if (atomic_read(&mm->mm_users) <= 1)
 		return 0;
 	if (mm->owner != p)
 		return 0;
 	return 1;
 }
 void mm_update_next_owner(struct mm_struct *mm)
 {
 	struct task_struct *c, *g, *p = current;
 retry:
 	if (!mm_need_new_owner(mm, p))
 		return;
 	read_lock(&tasklist_lock);
 	/*
 	 * Search in the children
 	 */
 	list_for_each_entry(c, &p->children, sibling) {
 		if (c->mm == mm)
 			goto assign_new_owner;
 	}
 	/*
 	 * Search in the siblings
 	 */
 	list_for_each_entry(c, &p->real_parent->children, sibling) {
 		if (c->mm == mm)
 			goto assign_new_owner;
 	}
 	/*
 	 * Search through everything else. We should not get
 	 * here often
 	 */
 	do_each_thread(g, c) {
 		if (c->mm == mm)
 			goto assign_new_owner;
 	} while_each_thread(g, c);
 	read_unlock(&tasklist_lock);
 	/*
 	 * We found no owner yet mm_users > 1: this implies that we are
 	 * most likely racing with swapoff (try_to_unuse()) or /proc or
 	 * ptrace or page migration (get_task_mm()).  Mark owner as NULL.
 	 */
 	mm->owner = NULL;
 	return;
 assign_new_owner:
 	BUG_ON(c == p);
 	get_task_struct(c);
 	/*
 	 * The task_lock protects c->mm from changing.
 	 * We always want mm->owner->mm == mm
 	 */
 	task_lock(c);
 	/*
 	 * Delay read_unlock() till we have the task_lock()
 	 * to ensure that c does not slip away underneath us
 	 */
 	read_unlock(&tasklist_lock);
 	if (c->mm != mm) {
 		task_unlock(c);
 		put_task_struct(c);
 		goto retry;
 	}
 	mm->owner = c;
 	task_unlock(c);
 	put_task_struct(c);
 }
 #endif /* CONFIG_MM_OWNER */
 /*
  * Turn us into a lazy TLB process if we
  * aren't already..
  */
 static void exit_mm(struct task_struct * tsk)
 {
 	struct mm_struct *mm = tsk->mm;
 	struct core_state *core_state;
 	mm_release(tsk, mm);
 	if (!mm)
 		return;
 	/*
 	 * Serialize with any possible pending coredump.
 	 * We must hold mmap_sem around checking core_state
 	 * and clearing tsk->mm.  The core-inducing thread
 	 * will increment ->nr_threads for each thread in the
 	 * group with ->mm != NULL.
 	 */
 	down_read(&mm->mmap_sem);
 	core_state = mm->core_state;
 	if (core_state) {
 		struct core_thread self;
 		up_read(&mm->mmap_sem);
 		self.task = tsk;
 		self.next = xchg(&core_state->dumper.next, &self);
 		/*
 		 * Implies mb(), the result of xchg() must be visible
 		 * to core_state->dumper.
 		 */
 		if (atomic_dec_and_test(&core_state->nr_threads))
 			complete(&core_state->startup);
 		for (;;) {
 			set_task_state(tsk, TASK_UNINTERRUPTIBLE);
 			if (!self.task) /* see coredump_finish() */
 				break;
 			schedule();
 		}
 		__set_task_state(tsk, TASK_RUNNING);
 		down_read(&mm->mmap_sem);
 	}
 	atomic_inc(&mm->mm_count);
 	BUG_ON(mm != tsk->active_mm);
 	/* more a memory barrier than a real lock */
 	task_lock(tsk);
 	tsk->mm = NULL;
 	up_read(&mm->mmap_sem);
 	enter_lazy_tlb(mm, current);
 	/* We don't want this task to be frozen prematurely */
 	clear_freeze_flag(tsk);
 	if (tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
 		atomic_dec(&mm->oom_disable_count);
 	task_unlock(tsk);
 	mm_update_next_owner(mm);
 	mmput(mm);
 }
 /*
  * When we die, we re-parent all our children.
  * Try to give them to another thread in our thread
  * group, and if no such member exists, give it to
  * the child reaper process (ie "init") in our pid
  * space.
  */
 static struct task_struct *find_new_reaper(struct task_struct *father)
 	__releases(&tasklist_lock)
 	__acquires(&tasklist_lock)
 {
 	struct pid_namespace *pid_ns = task_active_pid_ns(father);
 	struct task_struct *thread;
 	thread = father;
 	while_each_thread(father, thread) {
 		if (thread->flags & PF_EXITING)
 			continue;
 		if (unlikely(pid_ns->child_reaper == father))
 			pid_ns->child_reaper = thread;
 		return thread;
 	}
 	if (unlikely(pid_ns->child_reaper == father)) {
 		write_unlock_irq(&tasklist_lock);
 		if (unlikely(pid_ns == &init_pid_ns))
 			panic("Attempted to kill init!");
 		zap_pid_ns_processes(pid_ns);
 		write_lock_irq(&tasklist_lock);
 		/*
 		 * We can not clear ->child_reaper or leave it alone.
 		 * There may by stealth EXIT_DEAD tasks on ->children,
 		 * forget_original_parent() must move them somewhere.
 		 */
 		pid_ns->child_reaper = init_pid_ns.child_reaper;
 	}
 	return pid_ns->child_reaper;
 }
 /*
 * Any that need to be release_task'd are put on the @dead list.
  */
 static void reparent_leader(struct task_struct *father, struct task_struct *p,
 				struct list_head *dead)
 {
 	list_move_tail(&p->sibling, &p->real_parent->children);
 	if (task_detached(p))
 		return;
 	/*
 	 * If this is a threaded reparent there is no need to
 	 * notify anyone anything has happened.
 	 */
 	if (same_thread_group(p->real_parent, father))
 		return;
 	/* We don't want people slaying init.  */
 	p->exit_signal = SIGCHLD;
 	/* If it has exited notify the new parent about this child's death. */
 	if (!p->ptrace &&
 	    p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
 		do_notify_parent(p, p->exit_signal);
 		if (task_detached(p)) {
 			p->exit_state = EXIT_DEAD;
 			list_move_tail(&p->sibling, dead);
 		}
 	}
 	kill_orphaned_pgrp(p, father);
 }
 static void forget_original_parent(struct task_struct *father)
 {
 	struct task_struct *p, *n, *reaper;
 	LIST_HEAD(dead_children);
 	write_lock_irq(&tasklist_lock);
 	/*
 	 * Note that exit_ptrace() and find_new_reaper() might
 	 * drop tasklist_lock and reacquire it.
 	 */
 	exit_ptrace(father);
 	reaper = find_new_reaper(father);
 	list_for_each_entry_safe(p, n, &father->children, sibling) {
 		struct task_struct *t = p;
 		do {
 			t->real_parent = reaper;
 			if (t->parent == father) {
 				BUG_ON(t->ptrace);
 				t->parent = t->real_parent;
 			}
 			if (t->pdeath_signal)
 				group_send_sig_info(t->pdeath_signal,
 						    SEND_SIG_NOINFO, t);
 		} while_each_thread(p, t);
 		reparent_leader(father, p, &dead_children);
 	}
 	write_unlock_irq(&tasklist_lock);
 	BUG_ON(!list_empty(&father->children));
 	list_for_each_entry_safe(p, n, &dead_children, sibling) {
 		list_del_init(&p->sibling);
 		release_task(p);
 	}
 }
 /*
  * Send signals to all our closest relatives so that they know
  * to properly mourn us..
  */
 static void exit_notify(struct task_struct *tsk, int group_dead)
 {
 	int signal;
+	bool autoreap;
 	void *cookie;
 	/*
 	 * This does two things:
 	 *
   	 * A.  Make init inherit all the child processes
 	 * B.  Check to see if any process groups have become orphaned
 	 *	as a result of our exiting, and if they have any stopped
 	 *	jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
 	 */
 	forget_original_parent(tsk);
 	exit_task_namespaces(tsk);
 	write_lock_irq(&tasklist_lock);
 	if (group_dead)
 		kill_orphaned_pgrp(tsk->group_leader, NULL);
 	/* Let father know we died
 	 *
 	 * Thread signals are configurable, but you aren't going to use
 	 * that to send signals to arbitrary processes.
 	 * That stops right now.
 	 *
 	 * If the parent exec id doesn't match the exec id we saved
 	 * when we started then we know the parent has changed security
 	 * domain.
 	 *
 	 * If our self_exec id doesn't match our parent_exec_id then
 	 * we have changed execution domain as these two values started
 	 * the same after a fork.
 	 */
 	if (tsk->exit_signal != SIGCHLD && !task_detached(tsk) &&
 	    (tsk->parent_exec_id != tsk->real_parent->self_exec_id ||
 	     tsk->self_exec_id != tsk->parent_exec_id))
 		tsk->exit_signal = SIGCHLD;
 	signal = tracehook_notify_death(tsk, &cookie, group_dead);
 	if (signal >= 0)
-		signal = do_notify_parent(tsk, signal);
+		autoreap = do_notify_parent(tsk, signal);
+	else
+		autoreap = (signal == DEATH_REAP);
-	tsk->exit_state = signal == DEATH_REAP ? EXIT_DEAD : EXIT_ZOMBIE;
+	tsk->exit_state = autoreap ? EXIT_DEAD : EXIT_ZOMBIE;
 	/* mt-exec, de_thread() is waiting for group leader */
 	if (unlikely(tsk->signal->notify_count < 0))
 		wake_up_process(tsk->signal->group_exit_task);
 	write_unlock_irq(&tasklist_lock);
 	/* If the process is dead, release it - nobody will wait for it */
-	if (signal == DEATH_REAP)
+	if (autoreap)
 		release_task(tsk);
 }
 #ifdef CONFIG_DEBUG_STACK_USAGE
 static void check_stack_usage(void)
 {
 	static DEFINE_SPINLOCK(low_water_lock);
 	static int lowest_to_date = THREAD_SIZE;
 	unsigned long free;
 	free = stack_not_used(current);
 	if (free >= lowest_to_date)
 		return;
 	spin_lock(&low_water_lock);
 	if (free < lowest_to_date) {
 		printk(KERN_WARNING "%s used greatest stack depth: %lu bytes "
 				"left\n",
 				current->comm, free);
 		lowest_to_date = free;
 	}
 	spin_unlock(&low_water_lock);
 }
 #else
 static inline void check_stack_usage(void) {}
 #endif
 NORET_TYPE void do_exit(long code)
 {
 	struct task_struct *tsk = current;
 	int group_dead;
 	profile_task_exit(tsk);
 	WARN_ON(atomic_read(&tsk->fs_excl));
 	WARN_ON(blk_needs_flush_plug(tsk));
 	if (unlikely(in_interrupt()))
 		panic("Aiee, killing interrupt handler!");
 	if (unlikely(!tsk->pid))
 		panic("Attempted to kill the idle task!");
 	/*
 	 * If do_exit is called because this processes oopsed, it's possible
 	 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before
 	 * continuing. Amongst other possible reasons, this is to prevent
 	 * mm_release()->clear_child_tid() from writing to a user-controlled
 	 * kernel address.
 	 */
 	set_fs(USER_DS);
 	ptrace_event(PTRACE_EVENT_EXIT, code);
 	validate_creds_for_do_exit(tsk);
 	/*
 	 * We're taking recursive faults here in do_exit. Safest is to just
 	 * leave this task alone and wait for reboot.
 	 */
 	if (unlikely(tsk->flags & PF_EXITING)) {
 		printk(KERN_ALERT
 			"Fixing recursive fault but reboot is needed!\n");
 		/*
 		 * We can do this unlocked here. The futex code uses
 		 * this flag just to verify whether the pi state
 		 * cleanup has been done or not. In the worst case it
 		 * loops once more. We pretend that the cleanup was
 		 * done as there is no way to return. Either the
 		 * OWNER_DIED bit is set by now or we push the blocked
 		 * task into the wait for ever nirwana as well.
 		 */
 		tsk->flags |= PF_EXITPIDONE;
 		set_current_state(TASK_UNINTERRUPTIBLE);
 		schedule();
 	}
 	exit_irq_thread();
 	exit_signals(tsk);  /* sets PF_EXITING */
 	/*
 	 * tsk->flags are checked in the futex code to protect against
 	 * an exiting task cleaning up the robust pi futexes.
 	 */
 	smp_mb();
 	raw_spin_unlock_wait(&tsk->pi_lock);
 	if (unlikely(in_atomic()))
 		printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
 				current->comm, task_pid_nr(current),
 				preempt_count());
 	acct_update_integrals(tsk);
 	/* sync mm's RSS info before statistics gathering */
 	if (tsk->mm)
 		sync_mm_rss(tsk, tsk->mm);
 	group_dead = atomic_dec_and_test(&tsk->signal->live);
 	if (group_dead) {
 		hrtimer_cancel(&tsk->signal->real_timer);
 		exit_itimers(tsk->signal);
 		if (tsk->mm)
 			setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm);
 	}
 	acct_collect(code, group_dead);
 	if (group_dead)
 		tty_audit_exit();
 	if (unlikely(tsk->audit_context))
 		audit_free(tsk);
 	tsk->exit_code = code;
 	taskstats_exit(tsk, group_dead);
 	exit_mm(tsk);
 	if (group_dead)
 		acct_process();
 	trace_sched_process_exit(tsk);
 	exit_sem(tsk);
 	exit_files(tsk);
 	exit_fs(tsk);
 	check_stack_usage();
 	exit_thread();
 	/*
 	 * Flush inherited counters to the parent - before the parent
 	 * gets woken up by child-exit notifications.
 	 *
 	 * because of cgroup mode, must be called before cgroup_exit()
 	 */
 	perf_event_exit_task(tsk);
 	cgroup_exit(tsk, 1);
 	if (group_dead)
 		disassociate_ctty(1);
 	module_put(task_thread_info(tsk)->exec_domain->module);
 	proc_exit_connector(tsk);
 	/*
 	 * FIXME: do that only when needed, using sched_exit tracepoint
 	 */
 	ptrace_put_breakpoints(tsk);
 	exit_notify(tsk, group_dead);
 #ifdef CONFIG_NUMA
 	task_lock(tsk);
 	mpol_put(tsk->mempolicy);
 	tsk->mempolicy = NULL;
 	task_unlock(tsk);
 #endif
 #ifdef CONFIG_FUTEX
 	if (unlikely(current->pi_state_cache))
 		kfree(current->pi_state_cache);
 #endif
 	/*
 	 * Make sure we are holding no locks:
 	 */
 	debug_check_no_locks_held(tsk);
 	/*
 	 * We can do this unlocked here. The futex code uses this flag
 	 * just to verify whether the pi state cleanup has been done
 	 * or not. In the worst case it loops once more.
 	 */
 	tsk->flags |= PF_EXITPIDONE;
 	if (tsk->io_context)
 		exit_io_context(tsk);
 	if (tsk->splice_pipe)
 		__free_pipe_info(tsk->splice_pipe);
 	validate_creds_for_do_exit(tsk);
 	preempt_disable();
 	exit_rcu();
 	/* causes final put_task_struct in finish_task_switch(). */
 	tsk->state = TASK_DEAD;
 	schedule();
 	BUG();
 	/* Avoid "noreturn function does return".  */
 	for (;;)
 		cpu_relax();	/* For when BUG is null */
 }
 EXPORT_SYMBOL_GPL(do_exit);
 NORET_TYPE void complete_and_exit(struct completion *comp, long code)
 {
 	if (comp)
 		complete(comp);
 	do_exit(code);
 }
 EXPORT_SYMBOL(complete_and_exit);
 SYSCALL_DEFINE1(exit, int, error_code)
 {
 	do_exit((error_code&0xff)<<8);
 }
 /*
  * Take down every thread in the group.  This is called by fatal signals
  * as well as by sys_exit_group (below).
  */
 NORET_TYPE void
 do_group_exit(int exit_code)
 {
 	struct signal_struct *sig = current->signal;
 	BUG_ON(exit_code & 0x80); /* core dumps don't get here */
 	if (signal_group_exit(sig))
 		exit_code = sig->group_exit_code;
 	else if (!thread_group_empty(current)) {
 		struct sighand_struct *const sighand = current->sighand;
 		spin_lock_irq(&sighand->siglock);
 		if (signal_group_exit(sig))
 			/* Another thread got here before we took the lock.  */
 			exit_code = sig->group_exit_code;
 		else {
 			sig->group_exit_code = exit_code;
 			sig->flags = SIGNAL_GROUP_EXIT;
 			zap_other_threads(current);
 		}
 		spin_unlock_irq(&sighand->siglock);
 	}
 	do_exit(exit_code);
 	/* NOTREACHED */
 }
 /*
  * this kills every thread in the thread group. Note that any externally
  * wait4()-ing process will get the correct exit code - even if this
  * thread is not the thread group leader.
  */
 SYSCALL_DEFINE1(exit_group, int, error_code)
 {
 	do_group_exit((error_code & 0xff) << 8);
 	/* NOTREACHED */
 	return 0;
 }
 struct wait_opts {
 	enum pid_type		wo_type;
 	int			wo_flags;
 	struct pid		*wo_pid;
 	struct siginfo __user	*wo_info;
 	int __user		*wo_stat;
 	struct rusage __user	*wo_rusage;
 	wait_queue_t		child_wait;
 	int			notask_error;
 };
 static inline
 struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
 {
 	if (type != PIDTYPE_PID)
 		task = task->group_leader;
 	return task->pids[type].pid;
 }
 static int eligible_pid(struct wait_opts *wo, struct task_struct *p)
 {
 	return	wo->wo_type == PIDTYPE_MAX ||
 		task_pid_type(p, wo->wo_type) == wo->wo_pid;
 }
 static int eligible_child(struct wait_opts *wo, struct task_struct *p)
 {
 	if (!eligible_pid(wo, p))
 		return 0;
 	/* Wait for all children (clone and not) if __WALL is set;
 	 * otherwise, wait for clone children *only* if __WCLONE is
 	 * set; otherwise, wait for non-clone children *only*.  (Note:
 	 * A "clone" child here is one that reports to its parent
 	 * using a signal other than SIGCHLD.) */
 	if (((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
 	    && !(wo->wo_flags & __WALL))
 		return 0;
 	return 1;
 }
 static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p,
 				pid_t pid, uid_t uid, int why, int status)
 {
 	struct siginfo __user *infop;
 	int retval = wo->wo_rusage
 		? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
 	put_task_struct(p);
 	infop = wo->wo_info;
 	if (infop) {
 		if (!retval)
 			retval = put_user(SIGCHLD, &infop->si_signo);
 		if (!retval)
 			retval = put_user(0, &infop->si_errno);
 		if (!retval)
 			retval = put_user((short)why, &infop->si_code);
 		if (!retval)
 			retval = put_user(pid, &infop->si_pid);
 		if (!retval)
 			retval = put_user(uid, &infop->si_uid);
 		if (!retval)
 			retval = put_user(status, &infop->si_status);
 	}
 	if (!retval)
 		retval = pid;
 	return retval;
 }
 /*
  * Handle sys_wait4 work for one task in state EXIT_ZOMBIE.  We hold
  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
  * the lock and this task is uninteresting.  If we return nonzero, we have
  * released the lock and the system call should return.
  */
 static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
 {
 	unsigned long state;
 	int retval, status, traced;
 	pid_t pid = task_pid_vnr(p);
 	uid_t uid = __task_cred(p)->uid;
 	struct siginfo __user *infop;
 	if (!likely(wo->wo_flags & WEXITED))
 		return 0;
 	if (unlikely(wo->wo_flags & WNOWAIT)) {
 		int exit_code = p->exit_code;
 		int why;
 		get_task_struct(p);
 		read_unlock(&tasklist_lock);
 		if ((exit_code & 0x7f) == 0) {
 			why = CLD_EXITED;
 			status = exit_code >> 8;
 		} else {
 			why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
 			status = exit_code & 0x7f;
 		}
 		return wait_noreap_copyout(wo, p, pid, uid, why, status);
 	}
 	/*
 	 * Try to move the task's state to DEAD
 	 * only one thread is allowed to do this:
 	 */
 	state = xchg(&p->exit_state, EXIT_DEAD);
 	if (state != EXIT_ZOMBIE) {
 		BUG_ON(state != EXIT_DEAD);
 		return 0;
 	}
 	traced = ptrace_reparented(p);
 	/*
 	 * It can be ptraced but not reparented, check
 	 * !task_detached() to filter out sub-threads.
 	 */
 	if (likely(!traced) && likely(!task_detached(p))) {
 		struct signal_struct *psig;
 		struct signal_struct *sig;
 		unsigned long maxrss;
 		cputime_t tgutime, tgstime;
 		/*
 		 * The resource counters for the group leader are in its
 		 * own task_struct.  Those for dead threads in the group
 		 * are in its signal_struct, as are those for the child
 		 * processes it has previously reaped.  All these
 		 * accumulate in the parent's signal_struct c* fields.
 		 *
 		 * We don't bother to take a lock here to protect these
 		 * p->signal fields, because they are only touched by
 		 * __exit_signal, which runs with tasklist_lock
 		 * write-locked anyway, and so is excluded here.  We do
 		 * need to protect the access to parent->signal fields,
 		 * as other threads in the parent group can be right
 		 * here reaping other children at the same time.
 		 *
 		 * We use thread_group_times() to get times for the thread
 		 * group, which consolidates times for all threads in the
 		 * group including the group leader.
 		 */
 		thread_group_times(p, &tgutime, &tgstime);
 		spin_lock_irq(&p->real_parent->sighand->siglock);
 		psig = p->real_parent->signal;
 		sig = p->signal;
 		psig->cutime =
 			cputime_add(psig->cutime,
 			cputime_add(tgutime,
 				    sig->cutime));
 		psig->cstime =
 			cputime_add(psig->cstime,
 			cputime_add(tgstime,
 				    sig->cstime));
 		psig->cgtime =
 			cputime_add(psig->cgtime,
 			cputime_add(p->gtime,
 			cputime_add(sig->gtime,
 				    sig->cgtime)));
 		psig->cmin_flt +=
 			p->min_flt + sig->min_flt + sig->cmin_flt;
 		psig->cmaj_flt +=
 			p->maj_flt + sig->maj_flt + sig->cmaj_flt;
 		psig->cnvcsw +=
 			p->nvcsw + sig->nvcsw + sig->cnvcsw;
 		psig->cnivcsw +=
 			p->nivcsw + sig->nivcsw + sig->cnivcsw;
 		psig->cinblock +=
 			task_io_get_inblock(p) +
 			sig->inblock + sig->cinblock;
 		psig->coublock +=
 			task_io_get_oublock(p) +
 			sig->oublock + sig->coublock;
 		maxrss = max(sig->maxrss, sig->cmaxrss);
 		if (psig->cmaxrss < maxrss)
 			psig->cmaxrss = maxrss;
 		task_io_accounting_add(&psig->ioac, &p->ioac);
 		task_io_accounting_add(&psig->ioac, &sig->ioac);
 		spin_unlock_irq(&p->real_parent->sighand->siglock);
 	}
 	/*
 	 * Now we are sure this task is interesting, and no other
 	 * thread can reap it because we set its state to EXIT_DEAD.
 	 */
 	read_unlock(&tasklist_lock);
 	retval = wo->wo_rusage
 		? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
 	status = (p->signal->flags & SIGNAL_GROUP_EXIT)
 		? p->signal->group_exit_code : p->exit_code;
 	if (!retval && wo->wo_stat)
 		retval = put_user(status, wo->wo_stat);
 	infop = wo->wo_info;
 	if (!retval && infop)
 		retval = put_user(SIGCHLD, &infop->si_signo);
 	if (!retval && infop)
 		retval = put_user(0, &infop->si_errno);
 	if (!retval && infop) {
 		int why;
 		if ((status & 0x7f) == 0) {
 			why = CLD_EXITED;
 			status >>= 8;
 		} else {
 			why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
 			status &= 0x7f;
 		}
 		retval = put_user((short)why, &infop->si_code);
 		if (!retval)
 			retval = put_user(status, &infop->si_status);
 	}
 	if (!retval && infop)
 		retval = put_user(pid, &infop->si_pid);
 	if (!retval && infop)
 		retval = put_user(uid, &infop->si_uid);
 	if (!retval)
 		retval = pid;
 	if (traced) {
 		write_lock_irq(&tasklist_lock);
 		/* We dropped tasklist, ptracer could die and untrace */
 		ptrace_unlink(p);
 		/*
 		 * If this is not a detached task, notify the parent.
 		 * If it's still not detached after that, don't release
 		 * it now.
 		 */
 		if (!task_detached(p)) {
 			do_notify_parent(p, p->exit_signal);
 			if (!task_detached(p)) {
 				p->exit_state = EXIT_ZOMBIE;
 				p = NULL;
 			}
 		}
 		write_unlock_irq(&tasklist_lock);
 	}
 	if (p != NULL)
 		release_task(p);
 	return retval;
 }
 static int *task_stopped_code(struct task_struct *p, bool ptrace)
 {
 	if (ptrace) {
 		if (task_is_stopped_or_traced(p) &&
 		    !(p->jobctl & JOBCTL_LISTENING))
 			return &p->exit_code;
 	} else {
 		if (p->signal->flags & SIGNAL_STOP_STOPPED)
 			return &p->signal->group_exit_code;
 	}
 	return NULL;
 }
 /**
  * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED
  * @wo: wait options
  * @ptrace: is the wait for ptrace
  * @p: task to wait for
  *
  * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED.
  *
  * CONTEXT:
  * read_lock(&tasklist_lock), which is released if return value is
  * non-zero.  Also, grabs and releases @p->sighand->siglock.
  *
  * RETURNS:
  * 0 if wait condition didn't exist and search for other wait conditions
  * should continue.  Non-zero return, -errno on failure and @p's pid on
  * success, implies that tasklist_lock is released and wait condition
  * search should terminate.
  */
 static int wait_task_stopped(struct wait_opts *wo,
 				int ptrace, struct task_struct *p)
 {
 	struct siginfo __user *infop;
 	int retval, exit_code, *p_code, why;
 	uid_t uid = 0; /* unneeded, required by compiler */
 	pid_t pid;
 	/*
 	 * Traditionally we see ptrace'd stopped tasks regardless of options.
 	 */
 	if (!ptrace && !(wo->wo_flags & WUNTRACED))
 		return 0;
 	if (!task_stopped_code(p, ptrace))
 		return 0;
 	exit_code = 0;
 	spin_lock_irq(&p->sighand->siglock);
 	p_code = task_stopped_code(p, ptrace);
 	if (unlikely(!p_code))
 		goto unlock_sig;
 	exit_code = *p_code;
 	if (!exit_code)
 		goto unlock_sig;
 	if (!unlikely(wo->wo_flags & WNOWAIT))
 		*p_code = 0;
 	uid = task_uid(p);
 unlock_sig:
 	spin_unlock_irq(&p->sighand->siglock);
 	if (!exit_code)
 		return 0;
 	/*
 	 * Now we are pretty sure this task is interesting.
 	 * Make sure it doesn't get reaped out from under us while we
 	 * give up the lock and then examine it below.  We don't want to
 	 * keep holding onto the tasklist_lock while we call getrusage and
 	 * possibly take page faults for user memory.
 	 */
 	get_task_struct(p);
 	pid = task_pid_vnr(p);
 	why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
 	read_unlock(&tasklist_lock);
 	if (unlikely(wo->wo_flags & WNOWAIT))
 		return wait_noreap_copyout(wo, p, pid, uid, why, exit_code);
 	retval = wo->wo_rusage
 		? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
 	if (!retval && wo->wo_stat)
 		retval = put_user((exit_code << 8) | 0x7f, wo->wo_stat);
 	infop = wo->wo_info;
 	if (!retval && infop)
 		retval = put_user(SIGCHLD, &infop->si_signo);
 	if (!retval && infop)
 		retval = put_user(0, &infop->si_errno);
 	if (!retval && infop)
 		retval = put_user((short)why, &infop->si_code);
 	if (!retval && infop)
 		retval = put_user(exit_code, &infop->si_status);
 	if (!retval && infop)
 		retval = put_user(pid, &infop->si_pid);
 	if (!retval && infop)
 		retval = put_user(uid, &infop->si_uid);
 	if (!retval)
 		retval = pid;
 	put_task_struct(p);
 	BUG_ON(!retval);
 	return retval;
 }
 /*
  * Handle do_wait work for one task in a live, non-stopped state.
  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
  * the lock and this task is uninteresting.  If we return nonzero, we have
  * released the lock and the system call should return.
  */
 static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
 {
 	int retval;
 	pid_t pid;
 	uid_t uid;
 	if (!unlikely(wo->wo_flags & WCONTINUED))
 		return 0;
 	if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
 		return 0;
 	spin_lock_irq(&p->sighand->siglock);
 	/* Re-check with the lock held.  */
 	if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
 		spin_unlock_irq(&p->sighand->siglock);
 		return 0;
 	}
 	if (!unlikely(wo->wo_flags & WNOWAIT))
 		p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
 	uid = task_uid(p);
 	spin_unlock_irq(&p->sighand->siglock);
 	pid = task_pid_vnr(p);
 	get_task_struct(p);
 	read_unlock(&tasklist_lock);
 	if (!wo->wo_info) {
 		retval = wo->wo_rusage
 			? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
 		put_task_struct(p);
 		if (!retval && wo->wo_stat)
 			retval = put_user(0xffff, wo->wo_stat);
 		if (!retval)
 			retval = pid;
 	} else {
 		retval = wait_noreap_copyout(wo, p, pid, uid,
 					     CLD_CONTINUED, SIGCONT);
 		BUG_ON(retval == 0);
 	}
 	return retval;
 }
 /*
  * Consider @p for a wait by @parent.
  *
  * -ECHILD should be in ->notask_error before the first call.
  * Returns nonzero for a final return, when we have unlocked tasklist_lock.
  * Returns zero if the search for a child should continue;
  * then ->notask_error is 0 if @p is an eligible child,
  * or another error from security_task_wait(), or still -ECHILD.
  */
 static int wait_consider_task(struct wait_opts *wo, int ptrace,
 				struct task_struct *p)
 {
 	int ret = eligible_child(wo, p);
 	if (!ret)
 		return ret;
 	ret = security_task_wait(p);
 	if (unlikely(ret < 0)) {
 		/*
 		 * If we have not yet seen any eligible child,
 		 * then let this error code replace -ECHILD.
 		 * A permission error will give the user a clue
 		 * to look for security policy problems, rather
 		 * than for mysterious wait bugs.
 		 */
 		if (wo->notask_error)
 			wo->notask_error = ret;
 		return 0;
 	}
 	/* dead body doesn't have much to contribute */
 	if (p->exit_state == EXIT_DEAD)
 		return 0;
 	/* slay zombie? */
 	if (p->exit_state == EXIT_ZOMBIE) {
 		/*
 		 * A zombie ptracee is only visible to its ptracer.
 		 * Notification and reaping will be cascaded to the real
 		 * parent when the ptracer detaches.
 		 */
 		if (likely(!ptrace) && unlikely(p->ptrace)) {
 			/* it will become visible, clear notask_error */
 			wo->notask_error = 0;
 			return 0;
 		}
 		/* we don't reap group leaders with subthreads */
 		if (!delay_group_leader(p))
 			return wait_task_zombie(wo, p);
 		/*
 		 * Allow access to stopped/continued state via zombie by
 		 * falling through.  Clearing of notask_error is complex.
 		 *
 		 * When !@ptrace:
 		 *
 		 * If WEXITED is set, notask_error should naturally be
 		 * cleared.  If not, subset of WSTOPPED|WCONTINUED is set,
 		 * so, if there are live subthreads, there are events to
 		 * wait for.  If all subthreads are dead, it's still safe
 		 * to clear - this function will be called again in finite
 		 * amount time once all the subthreads are released and
 		 * will then return without clearing.
 		 *
 		 * When @ptrace:
 		 *
 		 * Stopped state is per-task and thus can't change once the
 		 * target task dies.  Only continued and exited can happen.
 		 * Clear notask_error if WCONTINUED | WEXITED.
 		 */
 		if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED)))
 			wo->notask_error = 0;
 	} else {
 		/*
 		 * If @p is ptraced by a task in its real parent's group,
 		 * hide group stop/continued state when looking at @p as
 		 * the real parent; otherwise, a single stop can be
 		 * reported twice as group and ptrace stops.
 		 *
 		 * If a ptracer wants to distinguish the two events for its
 		 * own children, it should create a separate process which
 		 * takes the role of real parent.
 		 */
 		if (likely(!ptrace) && p->ptrace &&
 		    same_thread_group(p->parent, p->real_parent))
 			return 0;
 		/*
 		 * @p is alive and it's gonna stop, continue or exit, so
 		 * there always is something to wait for.
 		 */
 		wo->notask_error = 0;
 	}
 	/*
 	 * Wait for stopped.  Depending on @ptrace, different stopped state
 	 * is used and the two don't interact with each other.
 	 */
 	ret = wait_task_stopped(wo, ptrace, p);
 	if (ret)
 		return ret;
 	/*
 	 * Wait for continued.  There's only one continued state and the
 	 * ptracer can consume it which can confuse the real parent.  Don't
 	 * use WCONTINUED from ptracer.  You don't need or want it.
 	 */
 	return wait_task_continued(wo, p);
 }
 /*
  * Do the work of do_wait() for one thread in the group, @tsk.
  *
  * -ECHILD should be in ->notask_error before the first call.
  * Returns nonzero for a final return, when we have unlocked tasklist_lock.
  * Returns zero if the search for a child should continue; then
  * ->notask_error is 0 if there were any eligible children,
  * or another error from security_task_wait(), or still -ECHILD.
  */
 static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk)
 {
 	struct task_struct *p;
 	list_for_each_entry(p, &tsk->children, sibling) {
 		int ret = wait_consider_task(wo, 0, p);
 		if (ret)
 			return ret;
 	}
 	return 0;
 }
 static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)
 {
 	struct task_struct *p;
 	list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
 		int ret = wait_consider_task(wo, 1, p);
 		if (ret)
 			return ret;
 	}
 	return 0;
 }
 static int child_wait_callback(wait_queue_t *wait, unsigned mode,
 				int sync, void *key)
 {
 	struct wait_opts *wo = container_of(wait, struct wait_opts,
 						child_wait);
 	struct task_struct *p = key;
 	if (!eligible_pid(wo, p))
 		return 0;
 	if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent)
 		return 0;
 	return default_wake_function(wait, mode, sync, key);
 }
 void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
 {
 	__wake_up_sync_key(&parent->signal->wait_chldexit,
 				TASK_INTERRUPTIBLE, 1, p);
 }
 static long do_wait(struct wait_opts *wo)
 {
 	struct task_struct *tsk;
 	int retval;
 	trace_sched_process_wait(wo->wo_pid);
 	init_waitqueue_func_entry(&wo->child_wait, child_wait_callback);
 	wo->child_wait.private = current;
 	add_wait_queue(&current->signal->wait_chldexit, &wo->child_wait);
 repeat:
 	/*
 	 * If there is nothing that can match our critiera just get out.
 	 * We will clear ->notask_error to zero if we see any child that
 	 * might later match our criteria, even if we are not able to reap
 	 * it yet.
 	 */
 	wo->notask_error = -ECHILD;
 	if ((wo->wo_type < PIDTYPE_MAX) &&
 	   (!wo->wo_pid || hlist_empty(&wo->wo_pid->tasks[wo->wo_type])))
 		goto notask;
 	set_current_state(TASK_INTERRUPTIBLE);
 	read_lock(&tasklist_lock);
 	tsk = current;
 	do {
 		retval = do_wait_thread(wo, tsk);
 		if (retval)
 			goto end;
 		retval = ptrace_do_wait(wo, tsk);
 		if (retval)
 			goto end;
 		if (wo->wo_flags & __WNOTHREAD)
 			break;
 	} while_each_thread(current, tsk);
 	read_unlock(&tasklist_lock);
 notask:
 	retval = wo->notask_error;
 	if (!retval && !(wo->wo_flags & WNOHANG)) {
 		retval = -ERESTARTSYS;
 		if (!signal_pending(current)) {
 			schedule();
 			goto repeat;
 		}
 	}
 end:
 	__set_current_state(TASK_RUNNING);
 	remove_wait_queue(&current->signal->wait_chldexit, &wo->child_wait);
 	return retval;
 }
 SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
 		infop, int, options, struct rusage __user *, ru)
 {
 	struct wait_opts wo;
 	struct pid *pid = NULL;
 	enum pid_type type;
 	long ret;
 	if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
 		return -EINVAL;
 	if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
 		return -EINVAL;
 	switch (which) {
 	case P_ALL:
 		type = PIDTYPE_MAX;
 		break;
 	case P_PID:
 		type = PIDTYPE_PID;
 		if (upid <= 0)
 			return -EINVAL;
 		break;
 	case P_PGID:
 		type = PIDTYPE_PGID;
 		if (upid <= 0)
 			return -EINVAL;
 		break;
 	default:
 		return -EINVAL;
 	}
 	if (type < PIDTYPE_MAX)
 		pid = find_get_pid(upid);
 	wo.wo_type	= type;
 	wo.wo_pid	= pid;
 	wo.wo_flags	= options;
 	wo.wo_info	= infop;
 	wo.wo_stat	= NULL;
 	wo.wo_rusage	= ru;
 	ret = do_wait(&wo);
 	if (ret > 0) {
 		ret = 0;
 	} else if (infop) {
 		/*
 		 * For a WNOHANG return, clear out all the fields
 		 * we would set so the user can easily tell the
 		 * difference.
 		 */
 		if (!ret)
 			ret = put_user(0, &infop->si_signo);
 		if (!ret)
 			ret = put_user(0, &infop->si_errno);
 		if (!ret)
 			ret = put_user(0, &infop->si_code);
 		if (!ret)
 			ret = put_user(0, &infop->si_pid);
 		if (!ret)
 			ret = put_user(0, &infop->si_uid);
 		if (!ret)
 			ret = put_user(0, &infop->si_status);
 	}
 	put_pid(pid);
 	/* avoid REGPARM breakage on x86: */
 	asmlinkage_protect(5, ret, which, upid, infop, options, ru);
 	return ret;
 }
 SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
 		int, options, struct rusage __user *, ru)
 {
 	struct wait_opts wo;
 	struct pid *pid = NULL;
 	enum pid_type type;
 	long ret;
 	if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
 			__WNOTHREAD|__WCLONE|__WALL))
 		return -EINVAL;
 	if (upid == -1)
 		type = PIDTYPE_MAX;
 	else if (upid < 0) {
 		type = PIDTYPE_PGID;
 		pid = find_get_pid(-upid);
 	} else if (upid == 0) {
 		type = PIDTYPE_PGID;
 		pid = get_task_pid(current, PIDTYPE_PGID);
 	} else /* upid > 0 */ {
 		type = PIDTYPE_PID;
 		pid = find_get_pid(upid);
 	}
 	wo.wo_type	= type;
 	wo.wo_pid	= pid;
 	wo.wo_flags	= options | WEXITED;
 	wo.wo_info	= NULL;
 	wo.wo_stat	= stat_addr;
 	wo.wo_rusage	= ru;
 	ret = do_wait(&wo);
 	put_pid(pid);
 	/* avoid REGPARM breakage on x86: */
 	asmlinkage_protect(4, ret, upid, stat_addr, options, ru);
 	return ret;
 }
 #ifdef __ARCH_WANT_SYS_WAITPID
 /*
  * sys_waitpid() remains for compatibility. waitpid() should be
  * implemented by calling sys_wait4() from libc.a.
  */
 SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
 {
 	return sys_wait4(pid, stat_addr, options, NULL);
 }
 #endif

kernel/signal.c

Diff comments View file @ 53c8f9f

 /*
  *  linux/kernel/signal.c
  *
  *  Copyright (C) 1991, 1992  Linus Torvalds
  *
  *  1997-11-02  Modified for POSIX.1b signals by Richard Henderson
  *
  *  2003-06-02  Jim Houston - Concurrent Computer Corp.
  *		Changes to use preallocated sigqueue structures
  *		to allow signals to be sent reliably.
  */
 #include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/sched.h>
 #include <linux/fs.h>
 #include <linux/tty.h>
 #include <linux/binfmts.h>
 #include <linux/security.h>
 #include <linux/syscalls.h>
 #include <linux/ptrace.h>
 #include <linux/signal.h>
 #include <linux/signalfd.h>
 #include <linux/ratelimit.h>
 #include <linux/tracehook.h>
 #include <linux/capability.h>
 #include <linux/freezer.h>
 #include <linux/pid_namespace.h>
 #include <linux/nsproxy.h>
 #define CREATE_TRACE_POINTS
 #include <trace/events/signal.h>
 #include <asm/param.h>
 #include <asm/uaccess.h>
 #include <asm/unistd.h>
 #include <asm/siginfo.h>
 #include "audit.h"	/* audit_signal_info() */
 /*
  * SLAB caches for signal bits.
  */
 static struct kmem_cache *sigqueue_cachep;
 int print_fatal_signals __read_mostly;
 static void __user *sig_handler(struct task_struct *t, int sig)
 {
 	return t->sighand->action[sig - 1].sa.sa_handler;
 }
 static int sig_handler_ignored(void __user *handler, int sig)
 {
 	/* Is it explicitly or implicitly ignored? */
 	return handler == SIG_IGN ||
 		(handler == SIG_DFL && sig_kernel_ignore(sig));
 }
 static int sig_task_ignored(struct task_struct *t, int sig,
 		int from_ancestor_ns)
 {
 	void __user *handler;
 	handler = sig_handler(t, sig);
 	if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
 			handler == SIG_DFL && !from_ancestor_ns)
 		return 1;
 	return sig_handler_ignored(handler, sig);
 }
 static int sig_ignored(struct task_struct *t, int sig, int from_ancestor_ns)
 {
 	/*
 	 * Blocked signals are never ignored, since the
 	 * signal handler may change by the time it is
 	 * unblocked.
 	 */
 	if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
 		return 0;
 	if (!sig_task_ignored(t, sig, from_ancestor_ns))
 		return 0;
 	/*
 	 * Tracers may want to know about even ignored signals.
 	 */
 	return !t->ptrace;
 }
 /*
  * Re-calculate pending state from the set of locally pending
  * signals, globally pending signals, and blocked signals.
  */
 static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked)
 {
 	unsigned long ready;
 	long i;
 	switch (_NSIG_WORDS) {
 	default:
 		for (i = _NSIG_WORDS, ready = 0; --i >= 0 ;)
 			ready |= signal->sig[i] &~ blocked->sig[i];
 		break;
 	case 4: ready  = signal->sig[3] &~ blocked->sig[3];
 		ready |= signal->sig[2] &~ blocked->sig[2];
 		ready |= signal->sig[1] &~ blocked->sig[1];
 		ready |= signal->sig[0] &~ blocked->sig[0];
 		break;
 	case 2: ready  = signal->sig[1] &~ blocked->sig[1];
 		ready |= signal->sig[0] &~ blocked->sig[0];
 		break;
 	case 1: ready  = signal->sig[0] &~ blocked->sig[0];
 	}
 	return ready !=	0;
 }
 #define PENDING(p,b) has_pending_signals(&(p)->signal, (b))
 static int recalc_sigpending_tsk(struct task_struct *t)
 {
 	if ((t->jobctl & JOBCTL_PENDING_MASK) ||
 	    PENDING(&t->pending, &t->blocked) ||
 	    PENDING(&t->signal->shared_pending, &t->blocked)) {
 		set_tsk_thread_flag(t, TIF_SIGPENDING);
 		return 1;
 	}
 	/*
 	 * We must never clear the flag in another thread, or in current
 	 * when it's possible the current syscall is returning -ERESTART*.
 	 * So we don't clear it here, and only callers who know they should do.
 	 */
 	return 0;
 }
 /*
  * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up.
  * This is superfluous when called on current, the wakeup is a harmless no-op.
  */
 void recalc_sigpending_and_wake(struct task_struct *t)
 {
 	if (recalc_sigpending_tsk(t))
 		signal_wake_up(t, 0);
 }
 void recalc_sigpending(void)
 {
 	if (!recalc_sigpending_tsk(current) && !freezing(current))
 		clear_thread_flag(TIF_SIGPENDING);
 }
 /* Given the mask, find the first available signal that should be serviced. */
 #define SYNCHRONOUS_MASK \
 	(sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
 	 sigmask(SIGTRAP) | sigmask(SIGFPE))
 int next_signal(struct sigpending *pending, sigset_t *mask)
 {
 	unsigned long i, *s, *m, x;
 	int sig = 0;
 	s = pending->signal.sig;
 	m = mask->sig;
 	/*
 	 * Handle the first word specially: it contains the
 	 * synchronous signals that need to be dequeued first.
 	 */
 	x = *s &~ *m;
 	if (x) {
 		if (x & SYNCHRONOUS_MASK)
 			x &= SYNCHRONOUS_MASK;
 		sig = ffz(~x) + 1;
 		return sig;
 	}
 	switch (_NSIG_WORDS) {
 	default:
 		for (i = 1; i < _NSIG_WORDS; ++i) {
 			x = *++s &~ *++m;
 			if (!x)
 				continue;
 			sig = ffz(~x) + i*_NSIG_BPW + 1;
 			break;
 		}
 		break;
 	case 2:
 		x = s[1] &~ m[1];
 		if (!x)
 			break;
 		sig = ffz(~x) + _NSIG_BPW + 1;
 		break;
 	case 1:
 		/* Nothing to do */
 		break;
 	}
 	return sig;
 }
 static inline void print_dropped_signal(int sig)
 {
 	static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
 	if (!print_fatal_signals)
 		return;
 	if (!__ratelimit(&ratelimit_state))
 		return;
 	printk(KERN_INFO "%s/%d: reached RLIMIT_SIGPENDING, dropped signal %d\n",
 				current->comm, current->pid, sig);
 }
 /**
  * task_set_jobctl_pending - set jobctl pending bits
  * @task: target task
  * @mask: pending bits to set
  *
  * Clear @mask from @task->jobctl.  @mask must be subset of
  * %JOBCTL_PENDING_MASK | %JOBCTL_STOP_CONSUME | %JOBCTL_STOP_SIGMASK |
  * %JOBCTL_TRAPPING.  If stop signo is being set, the existing signo is
  * cleared.  If @task is already being killed or exiting, this function
  * becomes noop.
  *
  * CONTEXT:
  * Must be called with @task->sighand->siglock held.
  *
  * RETURNS:
  * %true if @mask is set, %false if made noop because @task was dying.
  */
 bool task_set_jobctl_pending(struct task_struct *task, unsigned int mask)
 {
 	BUG_ON(mask & ~(JOBCTL_PENDING_MASK | JOBCTL_STOP_CONSUME |
 			JOBCTL_STOP_SIGMASK | JOBCTL_TRAPPING));
 	BUG_ON((mask & JOBCTL_TRAPPING) && !(mask & JOBCTL_PENDING_MASK));
 	if (unlikely(fatal_signal_pending(task) || (task->flags & PF_EXITING)))
 		return false;
 	if (mask & JOBCTL_STOP_SIGMASK)
 		task->jobctl &= ~JOBCTL_STOP_SIGMASK;
 	task->jobctl |= mask;
 	return true;
 }
 /**
  * task_clear_jobctl_trapping - clear jobctl trapping bit
  * @task: target task
  *
  * If JOBCTL_TRAPPING is set, a ptracer is waiting for us to enter TRACED.
  * Clear it and wake up the ptracer.  Note that we don't need any further
  * locking.  @task->siglock guarantees that @task->parent points to the
  * ptracer.
  *
  * CONTEXT:
  * Must be called with @task->sighand->siglock held.
  */
 void task_clear_jobctl_trapping(struct task_struct *task)
 {
 	if (unlikely(task->jobctl & JOBCTL_TRAPPING)) {
 		task->jobctl &= ~JOBCTL_TRAPPING;
 		wake_up_bit(&task->jobctl, JOBCTL_TRAPPING_BIT);
 	}
 }
 /**
  * task_clear_jobctl_pending - clear jobctl pending bits
  * @task: target task
  * @mask: pending bits to clear
  *
  * Clear @mask from @task->jobctl.  @mask must be subset of
  * %JOBCTL_PENDING_MASK.  If %JOBCTL_STOP_PENDING is being cleared, other
  * STOP bits are cleared together.
  *
  * If clearing of @mask leaves no stop or trap pending, this function calls
  * task_clear_jobctl_trapping().
  *
  * CONTEXT:
  * Must be called with @task->sighand->siglock held.
  */
 void task_clear_jobctl_pending(struct task_struct *task, unsigned int mask)
 {
 	BUG_ON(mask & ~JOBCTL_PENDING_MASK);
 	if (mask & JOBCTL_STOP_PENDING)
 		mask |= JOBCTL_STOP_CONSUME | JOBCTL_STOP_DEQUEUED;
 	task->jobctl &= ~mask;
 	if (!(task->jobctl & JOBCTL_PENDING_MASK))
 		task_clear_jobctl_trapping(task);
 }
 /**
  * task_participate_group_stop - participate in a group stop
  * @task: task participating in a group stop
  *
  * @task has %JOBCTL_STOP_PENDING set and is participating in a group stop.
  * Group stop states are cleared and the group stop count is consumed if
  * %JOBCTL_STOP_CONSUME was set.  If the consumption completes the group
  * stop, the appropriate %SIGNAL_* flags are set.
  *
  * CONTEXT:
  * Must be called with @task->sighand->siglock held.
  *
  * RETURNS:
  * %true if group stop completion should be notified to the parent, %false
  * otherwise.
  */
 static bool task_participate_group_stop(struct task_struct *task)
 {
 	struct signal_struct *sig = task->signal;
 	bool consume = task->jobctl & JOBCTL_STOP_CONSUME;
 	WARN_ON_ONCE(!(task->jobctl & JOBCTL_STOP_PENDING));
 	task_clear_jobctl_pending(task, JOBCTL_STOP_PENDING);
 	if (!consume)
 		return false;
 	if (!WARN_ON_ONCE(sig->group_stop_count == 0))
 		sig->group_stop_count--;
 	/*
 	 * Tell the caller to notify completion iff we are entering into a
 	 * fresh group stop.  Read comment in do_signal_stop() for details.
 	 */
 	if (!sig->group_stop_count && !(sig->flags & SIGNAL_STOP_STOPPED)) {
 		sig->flags = SIGNAL_STOP_STOPPED;
 		return true;
 	}
 	return false;
 }
 /*
  * allocate a new signal queue record
  * - this may be called without locks if and only if t == current, otherwise an
  *   appropriate lock must be held to stop the target task from exiting
  */
 static struct sigqueue *
 __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimit)
 {
 	struct sigqueue *q = NULL;
 	struct user_struct *user;
 	/*
 	 * Protect access to @t credentials. This can go away when all
 	 * callers hold rcu read lock.
 	 */
 	rcu_read_lock();
 	user = get_uid(__task_cred(t)->user);
 	atomic_inc(&user->sigpending);
 	rcu_read_unlock();
 	if (override_rlimit ||
 	    atomic_read(&user->sigpending) <=
 			task_rlimit(t, RLIMIT_SIGPENDING)) {
 		q = kmem_cache_alloc(sigqueue_cachep, flags);
 	} else {
 		print_dropped_signal(sig);
 	}
 	if (unlikely(q == NULL)) {
 		atomic_dec(&user->sigpending);
 		free_uid(user);
 	} else {
 		INIT_LIST_HEAD(&q->list);
 		q->flags = 0;
 		q->user = user;
 	}
 	return q;
 }
 static void __sigqueue_free(struct sigqueue *q)
 {
 	if (q->flags & SIGQUEUE_PREALLOC)
 		return;
 	atomic_dec(&q->user->sigpending);
 	free_uid(q->user);
 	kmem_cache_free(sigqueue_cachep, q);
 }
 void flush_sigqueue(struct sigpending *queue)
 {
 	struct sigqueue *q;
 	sigemptyset(&queue->signal);
 	while (!list_empty(&queue->list)) {
 		q = list_entry(queue->list.next, struct sigqueue , list);
 		list_del_init(&q->list);
 		__sigqueue_free(q);
 	}
 }
 /*
  * Flush all pending signals for a task.
  */
 void __flush_signals(struct task_struct *t)
 {
 	clear_tsk_thread_flag(t, TIF_SIGPENDING);
 	flush_sigqueue(&t->pending);
 	flush_sigqueue(&t->signal->shared_pending);
 }
 void flush_signals(struct task_struct *t)
 {
 	unsigned long flags;
 	spin_lock_irqsave(&t->sighand->siglock, flags);
 	__flush_signals(t);
 	spin_unlock_irqrestore(&t->sighand->siglock, flags);
 }
 static void __flush_itimer_signals(struct sigpending *pending)
 {
 	sigset_t signal, retain;
 	struct sigqueue *q, *n;
 	signal = pending->signal;
 	sigemptyset(&retain);
 	list_for_each_entry_safe(q, n, &pending->list, list) {
 		int sig = q->info.si_signo;
 		if (likely(q->info.si_code != SI_TIMER)) {
 			sigaddset(&retain, sig);
 		} else {
 			sigdelset(&signal, sig);
 			list_del_init(&q->list);
 			__sigqueue_free(q);
 		}
 	}
 	sigorsets(&pending->signal, &signal, &retain);
 }
 void flush_itimer_signals(void)
 {
 	struct task_struct *tsk = current;
 	unsigned long flags;
 	spin_lock_irqsave(&tsk->sighand->siglock, flags);
 	__flush_itimer_signals(&tsk->pending);
 	__flush_itimer_signals(&tsk->signal->shared_pending);
 	spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
 }
 void ignore_signals(struct task_struct *t)
 {
 	int i;
 	for (i = 0; i < _NSIG; ++i)
 		t->sighand->action[i].sa.sa_handler = SIG_IGN;
 	flush_signals(t);
 }
 /*
  * Flush all handlers for a task.
  */
 void
 flush_signal_handlers(struct task_struct *t, int force_default)
 {
 	int i;
 	struct k_sigaction *ka = &t->sighand->action[0];
 	for (i = _NSIG ; i != 0 ; i--) {
 		if (force_default || ka->sa.sa_handler != SIG_IGN)
 			ka->sa.sa_handler = SIG_DFL;
 		ka->sa.sa_flags = 0;
 		sigemptyset(&ka->sa.sa_mask);
 		ka++;
 	}
 }
 int unhandled_signal(struct task_struct *tsk, int sig)
 {
 	void __user *handler = tsk->sighand->action[sig-1].sa.sa_handler;
 	if (is_global_init(tsk))
 		return 1;
 	if (handler != SIG_IGN && handler != SIG_DFL)
 		return 0;
 	/* if ptraced, let the tracer determine */
 	return !tsk->ptrace;
 }
 /*
  * Notify the system that a driver wants to block all signals for this
  * process, and wants to be notified if any signals at all were to be
  * sent/acted upon.  If the notifier routine returns non-zero, then the
  * signal will be acted upon after all.  If the notifier routine returns 0,
  * then then signal will be blocked.  Only one block per process is
  * allowed.  priv is a pointer to private data that the notifier routine
  * can use to determine if the signal should be blocked or not.
  */
 void
 block_all_signals(int (*notifier)(void *priv), void *priv, sigset_t *mask)
 {
 	unsigned long flags;
 	spin_lock_irqsave(&current->sighand->siglock, flags);
 	current->notifier_mask = mask;
 	current->notifier_data = priv;
 	current->notifier = notifier;
 	spin_unlock_irqrestore(&current->sighand->siglock, flags);
 }
 /* Notify the system that blocking has ended. */
 void
 unblock_all_signals(void)
 {
 	unsigned long flags;
 	spin_lock_irqsave(&current->sighand->siglock, flags);
 	current->notifier = NULL;
 	current->notifier_data = NULL;
 	recalc_sigpending();
 	spin_unlock_irqrestore(&current->sighand->siglock, flags);
 }
 static void collect_signal(int sig, struct sigpending *list, siginfo_t *info)
 {
 	struct sigqueue *q, *first = NULL;
 	/*
 	 * Collect the siginfo appropriate to this signal.  Check if
 	 * there is another siginfo for the same signal.
 	*/
 	list_for_each_entry(q, &list->list, list) {
 		if (q->info.si_signo == sig) {
 			if (first)
 				goto still_pending;
 			first = q;
 		}
 	}
 	sigdelset(&list->signal, sig);
 	if (first) {
 still_pending:
 		list_del_init(&first->list);
 		copy_siginfo(info, &first->info);
 		__sigqueue_free(first);
 	} else {
 		/*
 		 * Ok, it wasn't in the queue.  This must be
 		 * a fast-pathed signal or we must have been
 		 * out of queue space.  So zero out the info.
 		 */
 		info->si_signo = sig;
 		info->si_errno = 0;
 		info->si_code = SI_USER;
 		info->si_pid = 0;
 		info->si_uid = 0;
 	}
 }
 static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
 			siginfo_t *info)
 {
 	int sig = next_signal(pending, mask);
 	if (sig) {
 		if (current->notifier) {
 			if (sigismember(current->notifier_mask, sig)) {
 				if (!(current->notifier)(current->notifier_data)) {
 					clear_thread_flag(TIF_SIGPENDING);
 					return 0;
 				}
 			}
 		}
 		collect_signal(sig, pending, info);
 	}
 	return sig;
 }
 /*
  * Dequeue a signal and return the element to the caller, which is
  * expected to free it.
  *
  * All callers have to hold the siglock.
  */
 int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
 {
 	int signr;
 	/* We only dequeue private signals from ourselves, we don't let
 	 * signalfd steal them
 	 */
 	signr = __dequeue_signal(&tsk->pending, mask, info);
 	if (!signr) {
 		signr = __dequeue_signal(&tsk->signal->shared_pending,
 					 mask, info);
 		/*
 		 * itimer signal ?
 		 *
 		 * itimers are process shared and we restart periodic
 		 * itimers in the signal delivery path to prevent DoS
 		 * attacks in the high resolution timer case. This is
 		 * compliant with the old way of self-restarting
 		 * itimers, as the SIGALRM is a legacy signal and only
 		 * queued once. Changing the restart behaviour to
 		 * restart the timer in the signal dequeue path is
 		 * reducing the timer noise on heavy loaded !highres
 		 * systems too.
 		 */
 		if (unlikely(signr == SIGALRM)) {
 			struct hrtimer *tmr = &tsk->signal->real_timer;
 			if (!hrtimer_is_queued(tmr) &&
 			    tsk->signal->it_real_incr.tv64 != 0) {
 				hrtimer_forward(tmr, tmr->base->get_time(),
 						tsk->signal->it_real_incr);
 				hrtimer_restart(tmr);
 			}
 		}
 	}
 	recalc_sigpending();
 	if (!signr)
 		return 0;
 	if (unlikely(sig_kernel_stop(signr))) {
 		/*
 		 * Set a marker that we have dequeued a stop signal.  Our
 		 * caller might release the siglock and then the pending
 		 * stop signal it is about to process is no longer in the
 		 * pending bitmasks, but must still be cleared by a SIGCONT
 		 * (and overruled by a SIGKILL).  So those cases clear this
 		 * shared flag after we've set it.  Note that this flag may
 		 * remain set after the signal we return is ignored or
 		 * handled.  That doesn't matter because its only purpose
 		 * is to alert stop-signal processing code when another
 		 * processor has come along and cleared the flag.
 		 */
 		current->jobctl |= JOBCTL_STOP_DEQUEUED;
 	}
 	if ((info->si_code & __SI_MASK) == __SI_TIMER && info->si_sys_private) {
 		/*
 		 * Release the siglock to ensure proper locking order
 		 * of timer locks outside of siglocks.  Note, we leave
 		 * irqs disabled here, since the posix-timers code is
 		 * about to disable them again anyway.
 		 */
 		spin_unlock(&tsk->sighand->siglock);
 		do_schedule_next_timer(info);
 		spin_lock(&tsk->sighand->siglock);
 	}
 	return signr;
 }
 /*
  * Tell a process that it has a new active signal..
  *
  * NOTE! we rely on the previous spin_lock to
  * lock interrupts for us! We can only be called with
  * "siglock" held, and the local interrupt must
  * have been disabled when that got acquired!
  *
  * No need to set need_resched since signal event passing
  * goes through ->blocked
  */
 void signal_wake_up(struct task_struct *t, int resume)
 {
 	unsigned int mask;
 	set_tsk_thread_flag(t, TIF_SIGPENDING);
 	/*
 	 * For SIGKILL, we want to wake it up in the stopped/traced/killable
 	 * case. We don't check t->state here because there is a race with it
 	 * executing another processor and just now entering stopped state.
 	 * By using wake_up_state, we ensure the process will wake up and
 	 * handle its death signal.
 	 */
 	mask = TASK_INTERRUPTIBLE;
 	if (resume)
 		mask |= TASK_WAKEKILL;
 	if (!wake_up_state(t, mask))
 		kick_process(t);
 }
 /*
  * Remove signals in mask from the pending set and queue.
  * Returns 1 if any signals were found.
  *
  * All callers must be holding the siglock.
  *
  * This version takes a sigset mask and looks at all signals,
  * not just those in the first mask word.
  */
 static int rm_from_queue_full(sigset_t *mask, struct sigpending *s)
 {
 	struct sigqueue *q, *n;
 	sigset_t m;
 	sigandsets(&m, mask, &s->signal);
 	if (sigisemptyset(&m))
 		return 0;
 	sigandnsets(&s->signal, &s->signal, mask);
 	list_for_each_entry_safe(q, n, &s->list, list) {
 		if (sigismember(mask, q->info.si_signo)) {
 			list_del_init(&q->list);
 			__sigqueue_free(q);
 		}
 	}
 	return 1;
 }
 /*
  * Remove signals in mask from the pending set and queue.
  * Returns 1 if any signals were found.
  *
  * All callers must be holding the siglock.
  */
 static int rm_from_queue(unsigned long mask, struct sigpending *s)
 {
 	struct sigqueue *q, *n;
 	if (!sigtestsetmask(&s->signal, mask))
 		return 0;
 	sigdelsetmask(&s->signal, mask);
 	list_for_each_entry_safe(q, n, &s->list, list) {
 		if (q->info.si_signo < SIGRTMIN &&
 		    (mask & sigmask(q->info.si_signo))) {
 			list_del_init(&q->list);
 			__sigqueue_free(q);
 		}
 	}
 	return 1;
 }
 static inline int is_si_special(const struct siginfo *info)
 {
 	return info <= SEND_SIG_FORCED;
 }
 static inline bool si_fromuser(const struct siginfo *info)
 {
 	return info == SEND_SIG_NOINFO ||
 		(!is_si_special(info) && SI_FROMUSER(info));
 }
 /*
  * called with RCU read lock from check_kill_permission()
  */
 static int kill_ok_by_cred(struct task_struct *t)
 {
 	const struct cred *cred = current_cred();
 	const struct cred *tcred = __task_cred(t);
 	if (cred->user->user_ns == tcred->user->user_ns &&
 	    (cred->euid == tcred->suid ||
 	     cred->euid == tcred->uid ||
 	     cred->uid  == tcred->suid ||
 	     cred->uid  == tcred->uid))
 		return 1;
 	if (ns_capable(tcred->user->user_ns, CAP_KILL))
 		return 1;
 	return 0;
 }
 /*
  * Bad permissions for sending the signal
  * - the caller must hold the RCU read lock
  */
 static int check_kill_permission(int sig, struct siginfo *info,
 				 struct task_struct *t)
 {
 	struct pid *sid;
 	int error;
 	if (!valid_signal(sig))
 		return -EINVAL;
 	if (!si_fromuser(info))
 		return 0;
 	error = audit_signal_info(sig, t); /* Let audit system see the signal */
 	if (error)
 		return error;
 	if (!same_thread_group(current, t) &&
 	    !kill_ok_by_cred(t)) {
 		switch (sig) {
 		case SIGCONT:
 			sid = task_session(t);
 			/*
 			 * We don't return the error if sid == NULL. The
 			 * task was unhashed, the caller must notice this.
 			 */
 			if (!sid || sid == task_session(current))
 				break;
 		default:
 			return -EPERM;
 		}
 	}
 	return security_task_kill(t, info, sig, 0);
 }
 /**
  * ptrace_trap_notify - schedule trap to notify ptracer
  * @t: tracee wanting to notify tracer
  *
  * This function schedules sticky ptrace trap which is cleared on the next
  * TRAP_STOP to notify ptracer of an event.  @t must have been seized by
  * ptracer.
  *
  * If @t is running, STOP trap will be taken.  If trapped for STOP and
  * ptracer is listening for events, tracee is woken up so that it can
  * re-trap for the new event.  If trapped otherwise, STOP trap will be
  * eventually taken without returning to userland after the existing traps
  * are finished by PTRACE_CONT.
  *
  * CONTEXT:
  * Must be called with @task->sighand->siglock held.
  */
 static void ptrace_trap_notify(struct task_struct *t)
 {
 	WARN_ON_ONCE(!(t->ptrace & PT_SEIZED));
 	assert_spin_locked(&t->sighand->siglock);
 	task_set_jobctl_pending(t, JOBCTL_TRAP_NOTIFY);
 	signal_wake_up(t, t->jobctl & JOBCTL_LISTENING);
 }
 /*
  * Handle magic process-wide effects of stop/continue signals. Unlike
  * the signal actions, these happen immediately at signal-generation
  * time regardless of blocking, ignoring, or handling.  This does the
  * actual continuing for SIGCONT, but not the actual stopping for stop
  * signals. The process stop is done as a signal action for SIG_DFL.
  *
  * Returns true if the signal should be actually delivered, otherwise
  * it should be dropped.
  */
 static int prepare_signal(int sig, struct task_struct *p, int from_ancestor_ns)
 {
 	struct signal_struct *signal = p->signal;
 	struct task_struct *t;
 	if (unlikely(signal->flags & SIGNAL_GROUP_EXIT)) {
 		/*
 		 * The process is in the middle of dying, nothing to do.
 		 */
 	} else if (sig_kernel_stop(sig)) {
 		/*
 		 * This is a stop signal.  Remove SIGCONT from all queues.
 		 */
 		rm_from_queue(sigmask(SIGCONT), &signal->shared_pending);
 		t = p;
 		do {
 			rm_from_queue(sigmask(SIGCONT), &t->pending);
 		} while_each_thread(p, t);
 	} else if (sig == SIGCONT) {
 		unsigned int why;
 		/*
 		 * Remove all stop signals from all queues, wake all threads.
 		 */
 		rm_from_queue(SIG_KERNEL_STOP_MASK, &signal->shared_pending);
 		t = p;
 		do {
 			task_clear_jobctl_pending(t, JOBCTL_STOP_PENDING);
 			rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending);
 			if (likely(!(t->ptrace & PT_SEIZED)))
 				wake_up_state(t, __TASK_STOPPED);
 			else
 				ptrace_trap_notify(t);
 		} while_each_thread(p, t);
 		/*
 		 * Notify the parent with CLD_CONTINUED if we were stopped.
 		 *
 		 * If we were in the middle of a group stop, we pretend it
 		 * was already finished, and then continued. Since SIGCHLD
 		 * doesn't queue we report only CLD_STOPPED, as if the next
 		 * CLD_CONTINUED was dropped.
 		 */
 		why = 0;
 		if (signal->flags & SIGNAL_STOP_STOPPED)
 			why |= SIGNAL_CLD_CONTINUED;
 		else if (signal->group_stop_count)
 			why |= SIGNAL_CLD_STOPPED;
 		if (why) {
 			/*
 			 * The first thread which returns from do_signal_stop()
 			 * will take ->siglock, notice SIGNAL_CLD_MASK, and
 			 * notify its parent. See get_signal_to_deliver().
 			 */
 			signal->flags = why | SIGNAL_STOP_CONTINUED;
 			signal->group_stop_count = 0;
 			signal->group_exit_code = 0;
 		}
 	}
 	return !sig_ignored(p, sig, from_ancestor_ns);
 }
 /*
  * Test if P wants to take SIG.  After we've checked all threads with this,
  * it's equivalent to finding no threads not blocking SIG.  Any threads not
  * blocking SIG were ruled out because they are not running and already
  * have pending signals.  Such threads will dequeue from the shared queue
  * as soon as they're available, so putting the signal on the shared queue
  * will be equivalent to sending it to one such thread.
  */
 static inline int wants_signal(int sig, struct task_struct *p)
 {
 	if (sigismember(&p->blocked, sig))
 		return 0;
 	if (p->flags & PF_EXITING)
 		return 0;
 	if (sig == SIGKILL)
 		return 1;
 	if (task_is_stopped_or_traced(p))
 		return 0;
 	return task_curr(p) || !signal_pending(p);
 }
 static void complete_signal(int sig, struct task_struct *p, int group)
 {
 	struct signal_struct *signal = p->signal;
 	struct task_struct *t;
 	/*
 	 * Now find a thread we can wake up to take the signal off the queue.
 	 *
 	 * If the main thread wants the signal, it gets first crack.
 	 * Probably the least surprising to the average bear.
 	 */
 	if (wants_signal(sig, p))
 		t = p;
 	else if (!group || thread_group_empty(p))
 		/*
 		 * There is just one thread and it does not need to be woken.
 		 * It will dequeue unblocked signals before it runs again.
 		 */
 		return;
 	else {
 		/*
 		 * Otherwise try to find a suitable thread.
 		 */
 		t = signal->curr_target;
 		while (!wants_signal(sig, t)) {
 			t = next_thread(t);
 			if (t == signal->curr_target)
 				/*
 				 * No thread needs to be woken.
 				 * Any eligible threads will see
 				 * the signal in the queue soon.
 				 */
 				return;
 		}
 		signal->curr_target = t;
 	}
 	/*
 	 * Found a killable thread.  If the signal will be fatal,
 	 * then start taking the whole group down immediately.
 	 */
 	if (sig_fatal(p, sig) &&
 	    !(signal->flags & (SIGNAL_UNKILLABLE | SIGNAL_GROUP_EXIT)) &&
 	    !sigismember(&t->real_blocked, sig) &&
 	    (sig == SIGKILL || !t->ptrace)) {
 		/*
 		 * This signal will be fatal to the whole group.
 		 */
 		if (!sig_kernel_coredump(sig)) {
 			/*
 			 * Start a group exit and wake everybody up.
 			 * This way we don't have other threads
 			 * running and doing things after a slower
 			 * thread has the fatal signal pending.
 			 */
 			signal->flags = SIGNAL_GROUP_EXIT;
 			signal->group_exit_code = sig;
 			signal->group_stop_count = 0;
 			t = p;
 			do {
 				task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
 				sigaddset(&t->pending.signal, SIGKILL);
 				signal_wake_up(t, 1);
 			} while_each_thread(p, t);
 			return;
 		}
 	}
 	/*
 	 * The signal is already in the shared-pending queue.
 	 * Tell the chosen thread to wake up and dequeue it.
 	 */
 	signal_wake_up(t, sig == SIGKILL);
 	return;
 }
 static inline int legacy_queue(struct sigpending *signals, int sig)
 {
 	return (sig < SIGRTMIN) && sigismember(&signals->signal, sig);
 }
 static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,
 			int group, int from_ancestor_ns)
 {
 	struct sigpending *pending;
 	struct sigqueue *q;
 	int override_rlimit;
 	trace_signal_generate(sig, info, t);
 	assert_spin_locked(&t->sighand->siglock);
 	if (!prepare_signal(sig, t, from_ancestor_ns))
 		return 0;
 	pending = group ? &t->signal->shared_pending : &t->pending;
 	/*
 	 * Short-circuit ignored signals and support queuing
 	 * exactly one non-rt signal, so that we can get more
 	 * detailed information about the cause of the signal.
 	 */
 	if (legacy_queue(pending, sig))
 		return 0;
 	/*
 	 * fast-pathed signals for kernel-internal things like SIGSTOP
 	 * or SIGKILL.
 	 */
 	if (info == SEND_SIG_FORCED)
 		goto out_set;
 	/*
 	 * Real-time signals must be queued if sent by sigqueue, or
 	 * some other real-time mechanism.  It is implementation
 	 * defined whether kill() does so.  We attempt to do so, on
 	 * the principle of least surprise, but since kill is not
 	 * allowed to fail with EAGAIN when low on memory we just
 	 * make sure at least one signal gets delivered and don't
 	 * pass on the info struct.
 	 */
 	if (sig < SIGRTMIN)
 		override_rlimit = (is_si_special(info) || info->si_code >= 0);
 	else
 		override_rlimit = 0;
 	q = __sigqueue_alloc(sig, t, GFP_ATOMIC | __GFP_NOTRACK_FALSE_POSITIVE,
 		override_rlimit);
 	if (q) {
 		list_add_tail(&q->list, &pending->list);
 		switch ((unsigned long) info) {
 		case (unsigned long) SEND_SIG_NOINFO:
 			q->info.si_signo = sig;
 			q->info.si_errno = 0;
 			q->info.si_code = SI_USER;
 			q->info.si_pid = task_tgid_nr_ns(current,
 							task_active_pid_ns(t));
 			q->info.si_uid = current_uid();
 			break;
 		case (unsigned long) SEND_SIG_PRIV:
 			q->info.si_signo = sig;
 			q->info.si_errno = 0;
 			q->info.si_code = SI_KERNEL;
 			q->info.si_pid = 0;
 			q->info.si_uid = 0;
 			break;
 		default:
 			copy_siginfo(&q->info, info);
 			if (from_ancestor_ns)
 				q->info.si_pid = 0;
 			break;
 		}
 	} else if (!is_si_special(info)) {
 		if (sig >= SIGRTMIN && info->si_code != SI_USER) {
 			/*
 			 * Queue overflow, abort.  We may abort if the
 			 * signal was rt and sent by user using something
 			 * other than kill().
 			 */
 			trace_signal_overflow_fail(sig, group, info);
 			return -EAGAIN;
 		} else {
 			/*
 			 * This is a silent loss of information.  We still
 			 * send the signal, but the *info bits are lost.
 			 */
 			trace_signal_lose_info(sig, group, info);
 		}
 	}
 out_set:
 	signalfd_notify(t, sig);
 	sigaddset(&pending->signal, sig);
 	complete_signal(sig, t, group);
 	return 0;
 }
 static int send_signal(int sig, struct siginfo *info, struct task_struct *t,
 			int group)
 {
 	int from_ancestor_ns = 0;
 #ifdef CONFIG_PID_NS
 	from_ancestor_ns = si_fromuser(info) &&
 			   !task_pid_nr_ns(current, task_active_pid_ns(t));
 #endif
 	return __send_signal(sig, info, t, group, from_ancestor_ns);
 }
 static void print_fatal_signal(struct pt_regs *regs, int signr)
 {
 	printk("%s/%d: potentially unexpected fatal signal %d.\n",
 		current->comm, task_pid_nr(current), signr);
 #if defined(__i386__) && !defined(__arch_um__)
 	printk("code at %08lx: ", regs->ip);
 	{
 		int i;
 		for (i = 0; i < 16; i++) {
 			unsigned char insn;
 			if (get_user(insn, (unsigned char *)(regs->ip + i)))
 				break;
 			printk("%02x ", insn);
 		}
 	}
 #endif
 	printk("\n");
 	preempt_disable();
 	show_regs(regs);
 	preempt_enable();
 }
 static int __init setup_print_fatal_signals(char *str)
 {
 	get_option (&str, &print_fatal_signals);
 	return 1;
 }
 __setup("print-fatal-signals=", setup_print_fatal_signals);
 int
 __group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
 {
 	return send_signal(sig, info, p, 1);
 }
 static int
 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
 {
 	return send_signal(sig, info, t, 0);
 }
 int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p,
 			bool group)
 {
 	unsigned long flags;
 	int ret = -ESRCH;
 	if (lock_task_sighand(p, &flags)) {
 		ret = send_signal(sig, info, p, group);
 		unlock_task_sighand(p, &flags);
 	}
 	return ret;
 }
 /*
  * Force a signal that the process can't ignore: if necessary
  * we unblock the signal and change any SIG_IGN to SIG_DFL.
  *
  * Note: If we unblock the signal, we always reset it to SIG_DFL,
  * since we do not want to have a signal handler that was blocked
  * be invoked when user space had explicitly blocked it.
  *
  * We don't want to have recursive SIGSEGV's etc, for example,
  * that is why we also clear SIGNAL_UNKILLABLE.
  */
 int
 force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
 {
 	unsigned long int flags;
 	int ret, blocked, ignored;
 	struct k_sigaction *action;
 	spin_lock_irqsave(&t->sighand->siglock, flags);
 	action = &t->sighand->action[sig-1];
 	ignored = action->sa.sa_handler == SIG_IGN;
 	blocked = sigismember(&t->blocked, sig);
 	if (blocked || ignored) {
 		action->sa.sa_handler = SIG_DFL;
 		if (blocked) {
 			sigdelset(&t->blocked, sig);
 			recalc_sigpending_and_wake(t);
 		}
 	}
 	if (action->sa.sa_handler == SIG_DFL)
 		t->signal->flags &= ~SIGNAL_UNKILLABLE;
 	ret = specific_send_sig_info(sig, info, t);
 	spin_unlock_irqrestore(&t->sighand->siglock, flags);
 	return ret;
 }
 /*
  * Nuke all other threads in the group.
  */
 int zap_other_threads(struct task_struct *p)
 {
 	struct task_struct *t = p;
 	int count = 0;
 	p->signal->group_stop_count = 0;
 	while_each_thread(p, t) {
 		task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
 		count++;
 		/* Don't bother with already dead threads */
 		if (t->exit_state)
 			continue;
 		sigaddset(&t->pending.signal, SIGKILL);
 		signal_wake_up(t, 1);
 	}
 	return count;
 }
 struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
 					   unsigned long *flags)
 {
 	struct sighand_struct *sighand;
 	rcu_read_lock();
 	for (;;) {
 		sighand = rcu_dereference(tsk->sighand);
 		if (unlikely(sighand == NULL))
 			break;
 		spin_lock_irqsave(&sighand->siglock, *flags);
 		if (likely(sighand == tsk->sighand))
 			break;
 		spin_unlock_irqrestore(&sighand->siglock, *flags);
 	}
 	rcu_read_unlock();
 	return sighand;
 }
 /*
  * send signal info to all the members of a group
  */
 int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
 {
 	int ret;
 	rcu_read_lock();
 	ret = check_kill_permission(sig, info, p);
 	rcu_read_unlock();
 	if (!ret && sig)
 		ret = do_send_sig_info(sig, info, p, true);
 	return ret;
 }
 /*
  * __kill_pgrp_info() sends a signal to a process group: this is what the tty
  * control characters do (^C, ^Z etc)
  * - the caller must hold at least a readlock on tasklist_lock
  */
 int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp)
 {
 	struct task_struct *p = NULL;
 	int retval, success;
 	success = 0;
 	retval = -ESRCH;
 	do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
 		int err = group_send_sig_info(sig, info, p);
 		success |= !err;
 		retval = err;
 	} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
 	return success ? 0 : retval;
 }
 int kill_pid_info(int sig, struct siginfo *info, struct pid *pid)
 {
 	int error = -ESRCH;
 	struct task_struct *p;
 	rcu_read_lock();
 retry:
 	p = pid_task(pid, PIDTYPE_PID);
 	if (p) {
 		error = group_send_sig_info(sig, info, p);
 		if (unlikely(error == -ESRCH))
 			/*
 			 * The task was unhashed in between, try again.
 			 * If it is dead, pid_task() will return NULL,
 			 * if we race with de_thread() it will find the
 			 * new leader.
 			 */
 			goto retry;
 	}
 	rcu_read_unlock();
 	return error;
 }
 int kill_proc_info(int sig, struct siginfo *info, pid_t pid)
 {
 	int error;
 	rcu_read_lock();
 	error = kill_pid_info(sig, info, find_vpid(pid));
 	rcu_read_unlock();
 	return error;
 }
 /* like kill_pid_info(), but doesn't use uid/euid of "current" */
 int kill_pid_info_as_uid(int sig, struct siginfo *info, struct pid *pid,
 		      uid_t uid, uid_t euid, u32 secid)
 {
 	int ret = -EINVAL;
 	struct task_struct *p;
 	const struct cred *pcred;
 	unsigned long flags;
 	if (!valid_signal(sig))
 		return ret;
 	rcu_read_lock();
 	p = pid_task(pid, PIDTYPE_PID);
 	if (!p) {
 		ret = -ESRCH;
 		goto out_unlock;
 	}
 	pcred = __task_cred(p);
 	if (si_fromuser(info) &&
 	    euid != pcred->suid && euid != pcred->uid &&
 	    uid  != pcred->suid && uid  != pcred->uid) {
 		ret = -EPERM;
 		goto out_unlock;
 	}
 	ret = security_task_kill(p, info, sig, secid);
 	if (ret)
 		goto out_unlock;
 	if (sig) {
 		if (lock_task_sighand(p, &flags)) {
 			ret = __send_signal(sig, info, p, 1, 0);
 			unlock_task_sighand(p, &flags);
 		} else
 			ret = -ESRCH;
 	}
 out_unlock:
 	rcu_read_unlock();
 	return ret;
 }
 EXPORT_SYMBOL_GPL(kill_pid_info_as_uid);
 /*
  * kill_something_info() interprets pid in interesting ways just like kill(2).
  *
  * POSIX specifies that kill(-1,sig) is unspecified, but what we have
  * is probably wrong.  Should make it like BSD or SYSV.
  */
 static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
 {
 	int ret;
 	if (pid > 0) {
 		rcu_read_lock();
 		ret = kill_pid_info(sig, info, find_vpid(pid));
 		rcu_read_unlock();
 		return ret;
 	}
 	read_lock(&tasklist_lock);
 	if (pid != -1) {
 		ret = __kill_pgrp_info(sig, info,
 				pid ? find_vpid(-pid) : task_pgrp(current));
 	} else {
 		int retval = 0, count = 0;
 		struct task_struct * p;
 		for_each_process(p) {
 			if (task_pid_vnr(p) > 1 &&
 					!same_thread_group(p, current)) {
 				int err = group_send_sig_info(sig, info, p);
 				++count;
 				if (err != -EPERM)
 					retval = err;
 			}
 		}
 		ret = count ? retval : -ESRCH;
 	}
 	read_unlock(&tasklist_lock);
 	return ret;
 }
 /*
  * These are for backward compatibility with the rest of the kernel source.
  */
 int send_sig_info(int sig, struct siginfo *info, struct task_struct *p)
 {
 	/*
 	 * Make sure legacy kernel users don't send in bad values
 	 * (normal paths check this in check_kill_permission).
 	 */
 	if (!valid_signal(sig))
 		return -EINVAL;
 	return do_send_sig_info(sig, info, p, false);
 }
 #define __si_special(priv) \
 	((priv) ? SEND_SIG_PRIV : SEND_SIG_NOINFO)
 int
 send_sig(int sig, struct task_struct *p, int priv)
 {
 	return send_sig_info(sig, __si_special(priv), p);
 }
 void
 force_sig(int sig, struct task_struct *p)
 {
 	force_sig_info(sig, SEND_SIG_PRIV, p);
 }
 /*
  * When things go south during signal handling, we
  * will force a SIGSEGV. And if the signal that caused
  * the problem was already a SIGSEGV, we'll want to
  * make sure we don't even try to deliver the signal..
  */
 int
 force_sigsegv(int sig, struct task_struct *p)
 {
 	if (sig == SIGSEGV) {
 		unsigned long flags;
 		spin_lock_irqsave(&p->sighand->siglock, flags);
 		p->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
 		spin_unlock_irqrestore(&p->sighand->siglock, flags);
 	}
 	force_sig(SIGSEGV, p);
 	return 0;
 }
 int kill_pgrp(struct pid *pid, int sig, int priv)
 {
 	int ret;
 	read_lock(&tasklist_lock);
 	ret = __kill_pgrp_info(sig, __si_special(priv), pid);
 	read_unlock(&tasklist_lock);
 	return ret;
 }
 EXPORT_SYMBOL(kill_pgrp);
 int kill_pid(struct pid *pid, int sig, int priv)
 {
 	return kill_pid_info(sig, __si_special(priv), pid);
 }
 EXPORT_SYMBOL(kill_pid);
 /*
  * These functions support sending signals using preallocated sigqueue
  * structures.  This is needed "because realtime applications cannot
  * afford to lose notifications of asynchronous events, like timer
  * expirations or I/O completions".  In the case of POSIX Timers
  * we allocate the sigqueue structure from the timer_create.  If this
  * allocation fails we are able to report the failure to the application
  * with an EAGAIN error.
  */
 struct sigqueue *sigqueue_alloc(void)
 {
 	struct sigqueue *q = __sigqueue_alloc(-1, current, GFP_KERNEL, 0);
 	if (q)
 		q->flags |= SIGQUEUE_PREALLOC;
 	return q;
 }
 void sigqueue_free(struct sigqueue *q)
 {
 	unsigned long flags;
 	spinlock_t *lock = &current->sighand->siglock;
 	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
 	/*
 	 * We must hold ->siglock while testing q->list
 	 * to serialize with collect_signal() or with
 	 * __exit_signal()->flush_sigqueue().
 	 */
 	spin_lock_irqsave(lock, flags);
 	q->flags &= ~SIGQUEUE_PREALLOC;
 	/*
 	 * If it is queued it will be freed when dequeued,
 	 * like the "regular" sigqueue.
 	 */
 	if (!list_empty(&q->list))
 		q = NULL;
 	spin_unlock_irqrestore(lock, flags);
 	if (q)
 		__sigqueue_free(q);
 }
 int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group)
 {
 	int sig = q->info.si_signo;
 	struct sigpending *pending;
 	unsigned long flags;
 	int ret;
 	BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
 	ret = -1;
 	if (!likely(lock_task_sighand(t, &flags)))
 		goto ret;
 	ret = 1; /* the signal is ignored */
 	if (!prepare_signal(sig, t, 0))
 		goto out;
 	ret = 0;
 	if (unlikely(!list_empty(&q->list))) {
 		/*
 		 * If an SI_TIMER entry is already queue just increment
 		 * the overrun count.
 		 */
 		BUG_ON(q->info.si_code != SI_TIMER);
 		q->info.si_overrun++;
 		goto out;
 	}
 	q->info.si_overrun = 0;
 	signalfd_notify(t, sig);
 	pending = group ? &t->signal->shared_pending : &t->pending;
 	list_add_tail(&q->list, &pending->list);
 	sigaddset(&pending->signal, sig);
 	complete_signal(sig, t, group);
 out:
 	unlock_task_sighand(t, &flags);
 ret:
 	return ret;
 }
 /*
  * Let a parent know about the death of a child.
  * For a stopped/continued status change, use do_notify_parent_cldstop instead.
  *
- * Returns -1 if our parent ignored us and so we've switched to
+ * Returns true if our parent ignored us and so we've switched to
- * self-reaping, or else @sig.
+ * self-reaping.
  */
-int do_notify_parent(struct task_struct *tsk, int sig)
+bool do_notify_parent(struct task_struct *tsk, int sig)
 {
 	struct siginfo info;
 	unsigned long flags;
 	struct sighand_struct *psig;
-	int ret = sig;
+	bool autoreap = false;
 	BUG_ON(sig == -1);
  	/* do_notify_parent_cldstop should have been called instead.  */
  	BUG_ON(task_is_stopped_or_traced(tsk));
 	BUG_ON(!tsk->ptrace &&
 	       (tsk->group_leader != tsk || !thread_group_empty(tsk)));
 	info.si_signo = sig;
 	info.si_errno = 0;
 	/*
 	 * we are under tasklist_lock here so our parent is tied to
 	 * us and cannot exit and release its namespace.
 	 *
 	 * the only it can is to switch its nsproxy with sys_unshare,
 	 * bu uncharing pid namespaces is not allowed, so we'll always
 	 * see relevant namespace
 	 *
 	 * write_lock() currently calls preempt_disable() which is the
 	 * same as rcu_read_lock(), but according to Oleg, this is not
 	 * correct to rely on this
 	 */
 	rcu_read_lock();
 	info.si_pid = task_pid_nr_ns(tsk, tsk->parent->nsproxy->pid_ns);
 	info.si_uid = __task_cred(tsk)->uid;
 	rcu_read_unlock();
 	info.si_utime = cputime_to_clock_t(cputime_add(tsk->utime,
 				tsk->signal->utime));
 	info.si_stime = cputime_to_clock_t(cputime_add(tsk->stime,
 				tsk->signal->stime));
 	info.si_status = tsk->exit_code & 0x7f;
 	if (tsk->exit_code & 0x80)
 		info.si_code = CLD_DUMPED;
 	else if (tsk->exit_code & 0x7f)
 		info.si_code = CLD_KILLED;
 	else {
 		info.si_code = CLD_EXITED;
 		info.si_status = tsk->exit_code >> 8;
 	}
 	psig = tsk->parent->sighand;
 	spin_lock_irqsave(&psig->siglock, flags);
 	if (!tsk->ptrace && sig == SIGCHLD &&
 	    (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
 	     (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT))) {
 		/*
 		 * We are exiting and our parent doesn't care.  POSIX.1
 		 * defines special semantics for setting SIGCHLD to SIG_IGN
 		 * or setting the SA_NOCLDWAIT flag: we should be reaped
 		 * automatically and not left for our parent's wait4 call.
 		 * Rather than having the parent do it as a magic kind of
 		 * signal handler, we just set this to tell do_exit that we
 		 * can be cleaned up without becoming a zombie.  Note that
 		 * we still call __wake_up_parent in this case, because a
 		 * blocked sys_wait4 might now return -ECHILD.
 		 *
 		 * Whether we send SIGCHLD or not for SA_NOCLDWAIT
 		 * is implementation-defined: we do (if you don't want
 		 * it, just use SIG_IGN instead).
 		 */
-		ret = tsk->exit_signal = -1;
+		autoreap = true;
+		tsk->exit_signal = -1;
 		if (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN)
-			sig = -1;
+			sig = 0;
 	}
-	if (valid_signal(sig) && sig > 0)
+	if (valid_signal(sig) && sig)
 		__group_send_sig_info(sig, &info, tsk->parent);
 	__wake_up_parent(tsk, tsk->parent);
 	spin_unlock_irqrestore(&psig->siglock, flags);
-	return ret;
+	return autoreap;
 }
 /**
  * do_notify_parent_cldstop - notify parent of stopped/continued state change
  * @tsk: task reporting the state change
  * @for_ptracer: the notification is for ptracer
  * @why: CLD_{CONTINUED|STOPPED|TRAPPED} to report
  *
  * Notify @tsk's parent that the stopped/continued state has changed.  If
  * @for_ptracer is %false, @tsk's group leader notifies to its real parent.
  * If %true, @tsk reports to @tsk->parent which should be the ptracer.
  *
  * CONTEXT:
  * Must be called with tasklist_lock at least read locked.
  */
 static void do_notify_parent_cldstop(struct task_struct *tsk,
 				     bool for_ptracer, int why)
 {
 	struct siginfo info;
 	unsigned long flags;
 	struct task_struct *parent;
 	struct sighand_struct *sighand;
 	if (for_ptracer) {
 		parent = tsk->parent;
 	} else {
 		tsk = tsk->group_leader;
 		parent = tsk->real_parent;
 	}
 	info.si_signo = SIGCHLD;
 	info.si_errno = 0;
 	/*
 	 * see comment in do_notify_parent() about the following 4 lines
 	 */
 	rcu_read_lock();
 	info.si_pid = task_pid_nr_ns(tsk, parent->nsproxy->pid_ns);
 	info.si_uid = __task_cred(tsk)->uid;
 	rcu_read_unlock();
 	info.si_utime = cputime_to_clock_t(tsk->utime);
 	info.si_stime = cputime_to_clock_t(tsk->stime);
  	info.si_code = why;
  	switch (why) {
  	case CLD_CONTINUED:
  		info.si_status = SIGCONT;
  		break;
  	case CLD_STOPPED:
  		info.si_status = tsk->signal->group_exit_code & 0x7f;
  		break;
  	case CLD_TRAPPED:
  		info.si_status = tsk->exit_code & 0x7f;
  		break;
  	default:
  		BUG();
  	}
 	sighand = parent->sighand;
 	spin_lock_irqsave(&sighand->siglock, flags);
 	if (sighand->action[SIGCHLD-1].sa.sa_handler != SIG_IGN &&
 	    !(sighand->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
 		__group_send_sig_info(SIGCHLD, &info, parent);
 	/*
 	 * Even if SIGCHLD is not generated, we must wake up wait4 calls.
 	 */
 	__wake_up_parent(tsk, parent);
 	spin_unlock_irqrestore(&sighand->siglock, flags);
 }
 static inline int may_ptrace_stop(void)
 {
 	if (!likely(current->ptrace))
 		return 0;
 	/*
 	 * Are we in the middle of do_coredump?
 	 * If so and our tracer is also part of the coredump stopping
 	 * is a deadlock situation, and pointless because our tracer
 	 * is dead so don't allow us to stop.
 	 * If SIGKILL was already sent before the caller unlocked
 	 * ->siglock we must see ->core_state != NULL. Otherwise it
 	 * is safe to enter schedule().
 	 */
 	if (unlikely(current->mm->core_state) &&
 	    unlikely(current->mm == current->parent->mm))
 		return 0;
 	return 1;
 }
 /*
  * Return non-zero if there is a SIGKILL that should be waking us up.
  * Called with the siglock held.
  */
 static int sigkill_pending(struct task_struct *tsk)
 {
 	return	sigismember(&tsk->pending.signal, SIGKILL) ||
 		sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
 }
 /*
  * Test whether the target task of the usual cldstop notification - the
  * real_parent of @child - is in the same group as the ptracer.
  */
 static bool real_parent_is_ptracer(struct task_struct *child)
 {
 	return same_thread_group(child->parent, child->real_parent);
 }
 /*
  * This must be called with current->sighand->siglock held.
  *
  * This should be the path for all ptrace stops.
  * We always set current->last_siginfo while stopped here.
  * That makes it a way to test a stopped process for
  * being ptrace-stopped vs being job-control-stopped.
  *
  * If we actually decide not to stop at all because the tracer
  * is gone, we keep current->exit_code unless clear_code.
  */
 static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
 	__releases(&current->sighand->siglock)
 	__acquires(&current->sighand->siglock)
 {
 	bool gstop_done = false;
 	if (arch_ptrace_stop_needed(exit_code, info)) {
 		/*
 		 * The arch code has something special to do before a
 		 * ptrace stop.  This is allowed to block, e.g. for faults
 		 * on user stack pages.  We can't keep the siglock while
 		 * calling arch_ptrace_stop, so we must release it now.
 		 * To preserve proper semantics, we must do this before
 		 * any signal bookkeeping like checking group_stop_count.
 		 * Meanwhile, a SIGKILL could come in before we retake the
 		 * siglock.  That must prevent us from sleeping in TASK_TRACED.
 		 * So after regaining the lock, we must check for SIGKILL.
 		 */
 		spin_unlock_irq(&current->sighand->siglock);
 		arch_ptrace_stop(exit_code, info);
 		spin_lock_irq(&current->sighand->siglock);
 		if (sigkill_pending(current))
 			return;
 	}
 	/*
 	 * We're committing to trapping.  TRACED should be visible before
 	 * TRAPPING is cleared; otherwise, the tracer might fail do_wait().
 	 * Also, transition to TRACED and updates to ->jobctl should be
 	 * atomic with respect to siglock and should be done after the arch
 	 * hook as siglock is released and regrabbed across it.
 	 */
 	set_current_state(TASK_TRACED);
 	current->last_siginfo = info;
 	current->exit_code = exit_code;
 	/*
 	 * If @why is CLD_STOPPED, we're trapping to participate in a group
 	 * stop.  Do the bookkeeping.  Note that if SIGCONT was delievered
 	 * across siglock relocks since INTERRUPT was scheduled, PENDING
 	 * could be clear now.  We act as if SIGCONT is received after
 	 * TASK_TRACED is entered - ignore it.
 	 */
 	if (why == CLD_STOPPED && (current->jobctl & JOBCTL_STOP_PENDING))
 		gstop_done = task_participate_group_stop(current);
 	/* any trap clears pending STOP trap, STOP trap clears NOTIFY */
 	task_clear_jobctl_pending(current, JOBCTL_TRAP_STOP);
 	if (info && info->si_code >> 8 == PTRACE_EVENT_STOP)
 		task_clear_jobctl_pending(current, JOBCTL_TRAP_NOTIFY);
 	/* entering a trap, clear TRAPPING */
 	task_clear_jobctl_trapping(current);
 	spin_unlock_irq(&current->sighand->siglock);
 	read_lock(&tasklist_lock);
 	if (may_ptrace_stop()) {
 		/*
 		 * Notify parents of the stop.
 		 *
 		 * While ptraced, there are two parents - the ptracer and
 		 * the real_parent of the group_leader.  The ptracer should
 		 * know about every stop while the real parent is only
 		 * interested in the completion of group stop.  The states
 		 * for the two don't interact with each other.  Notify
 		 * separately unless they're gonna be duplicates.
 		 */
 		do_notify_parent_cldstop(current, true, why);
 		if (gstop_done && !real_parent_is_ptracer(current))
 			do_notify_parent_cldstop(current, false, why);
 		/*
 		 * Don't want to allow preemption here, because
 		 * sys_ptrace() needs this task to be inactive.
 		 *
 		 * XXX: implement read_unlock_no_resched().
 		 */
 		preempt_disable();
 		read_unlock(&tasklist_lock);
 		preempt_enable_no_resched();
 		schedule();
 	} else {
 		/*
 		 * By the time we got the lock, our tracer went away.
 		 * Don't drop the lock yet, another tracer may come.
 		 *
 		 * If @gstop_done, the ptracer went away between group stop
 		 * completion and here.  During detach, it would have set
 		 * JOBCTL_STOP_PENDING on us and we'll re-enter
 		 * TASK_STOPPED in do_signal_stop() on return, so notifying
 		 * the real parent of the group stop completion is enough.
 		 */
 		if (gstop_done)
 			do_notify_parent_cldstop(current, false, why);
 		__set_current_state(TASK_RUNNING);
 		if (clear_code)
 			current->exit_code = 0;
 		read_unlock(&tasklist_lock);
 	}
 	/*
 	 * While in TASK_TRACED, we were considered "frozen enough".
 	 * Now that we woke up, it's crucial if we're supposed to be
 	 * frozen that we freeze now before running anything substantial.
 	 */
 	try_to_freeze();
 	/*
 	 * We are back.  Now reacquire the siglock before touching
 	 * last_siginfo, so that we are sure to have synchronized with
 	 * any signal-sending on another CPU that wants to examine it.
 	 */
 	spin_lock_irq(&current->sighand->siglock);
 	current->last_siginfo = NULL;
 	/* LISTENING can be set only during STOP traps, clear it */
 	current->jobctl &= ~JOBCTL_LISTENING;
 	/*
 	 * Queued signals ignored us while we were stopped for tracing.
 	 * So check for any that we should take before resuming user mode.
 	 * This sets TIF_SIGPENDING, but never clears it.
 	 */
 	recalc_sigpending_tsk(current);
 }
 static void ptrace_do_notify(int signr, int exit_code, int why)
 {
 	siginfo_t info;
 	memset(&info, 0, sizeof info);
 	info.si_signo = signr;
 	info.si_code = exit_code;
 	info.si_pid = task_pid_vnr(current);
 	info.si_uid = current_uid();
 	/* Let the debugger run.  */
 	ptrace_stop(exit_code, why, 1, &info);
 }
 void ptrace_notify(int exit_code)
 {
 	BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
 	spin_lock_irq(&current->sighand->siglock);
 	ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
 	spin_unlock_irq(&current->sighand->siglock);
 }
 /**
  * do_signal_stop - handle group stop for SIGSTOP and other stop signals
  * @signr: signr causing group stop if initiating
  *
  * If %JOBCTL_STOP_PENDING is not set yet, initiate group stop with @signr
  * and participate in it.  If already set, participate in the existing
  * group stop.  If participated in a group stop (and thus slept), %true is
  * returned with siglock released.
  *
  * If ptraced, this function doesn't handle stop itself.  Instead,
  * %JOBCTL_TRAP_STOP is scheduled and %false is returned with siglock
  * untouched.  The caller must ensure that INTERRUPT trap handling takes
  * places afterwards.
  *
  * CONTEXT:
  * Must be called with @current->sighand->siglock held, which is released
  * on %true return.
  *
  * RETURNS:
  * %false if group stop is already cancelled or ptrace trap is scheduled.
  * %true if participated in group stop.
  */
 static bool do_signal_stop(int signr)
 	__releases(&current->sighand->siglock)
 {
 	struct signal_struct *sig = current->signal;
 	if (!(current->jobctl & JOBCTL_STOP_PENDING)) {
 		unsigned int gstop = JOBCTL_STOP_PENDING | JOBCTL_STOP_CONSUME;
 		struct task_struct *t;
 		/* signr will be recorded in task->jobctl for retries */
 		WARN_ON_ONCE(signr & ~JOBCTL_STOP_SIGMASK);
 		if (!likely(current->jobctl & JOBCTL_STOP_DEQUEUED) ||
 		    unlikely(signal_group_exit(sig)))
 			return false;
 		/*
 		 * There is no group stop already in progress.  We must
 		 * initiate one now.
 		 *
 		 * While ptraced, a task may be resumed while group stop is
 		 * still in effect and then receive a stop signal and
 		 * initiate another group stop.  This deviates from the
 		 * usual behavior as two consecutive stop signals can't
 		 * cause two group stops when !ptraced.  That is why we
 		 * also check !task_is_stopped(t) below.
 		 *
 		 * The condition can be distinguished by testing whether
 		 * SIGNAL_STOP_STOPPED is already set.  Don't generate
 		 * group_exit_code in such case.
 		 *
 		 * This is not necessary for SIGNAL_STOP_CONTINUED because
 		 * an intervening stop signal is required to cause two
 		 * continued events regardless of ptrace.
 		 */
 		if (!(sig->flags & SIGNAL_STOP_STOPPED))
 			sig->group_exit_code = signr;
 		else
 			WARN_ON_ONCE(!current->ptrace);
 		sig->group_stop_count = 0;
 		if (task_set_jobctl_pending(current, signr | gstop))
 			sig->group_stop_count++;
 		for (t = next_thread(current); t != current;
 		     t = next_thread(t)) {
 			/*
 			 * Setting state to TASK_STOPPED for a group
 			 * stop is always done with the siglock held,
 			 * so this check has no races.
 			 */
 			if (!task_is_stopped(t) &&
 			    task_set_jobctl_pending(t, signr | gstop)) {
 				sig->group_stop_count++;
 				if (likely(!(t->ptrace & PT_SEIZED)))
 					signal_wake_up(t, 0);
 				else
 					ptrace_trap_notify(t);
 			}
 		}
 	}
 	if (likely(!current->ptrace)) {
 		int notify = 0;
 		/*
 		 * If there are no other threads in the group, or if there
 		 * is a group stop in progress and we are the last to stop,
 		 * report to the parent.
 		 */
 		if (task_participate_group_stop(current))
 			notify = CLD_STOPPED;
 		__set_current_state(TASK_STOPPED);
 		spin_unlock_irq(&current->sighand->siglock);
 		/*
 		 * Notify the parent of the group stop completion.  Because
 		 * we're not holding either the siglock or tasklist_lock
 		 * here, ptracer may attach inbetween; however, this is for
 		 * group stop and should always be delivered to the real
 		 * parent of the group leader.  The new ptracer will get
 		 * its notification when this task transitions into
 		 * TASK_TRACED.
 		 */
 		if (notify) {
 			read_lock(&tasklist_lock);
 			do_notify_parent_cldstop(current, false, notify);
 			read_unlock(&tasklist_lock);
 		}
 		/* Now we don't run again until woken by SIGCONT or SIGKILL */
 		schedule();
 		return true;
 	} else {
 		/*
 		 * While ptraced, group stop is handled by STOP trap.
 		 * Schedule it and let the caller deal with it.
 		 */
 		task_set_jobctl_pending(current, JOBCTL_TRAP_STOP);
 		return false;
 	}
 }
 /**
  * do_jobctl_trap - take care of ptrace jobctl traps
  *
  * When PT_SEIZED, it's used for both group stop and explicit
  * SEIZE/INTERRUPT traps.  Both generate PTRACE_EVENT_STOP trap with
  * accompanying siginfo.  If stopped, lower eight bits of exit_code contain
  * the stop signal; otherwise, %SIGTRAP.
  *
  * When !PT_SEIZED, it's used only for group stop trap with stop signal
  * number as exit_code and no siginfo.
  *
  * CONTEXT:
  * Must be called with @current->sighand->siglock held, which may be
  * released and re-acquired before returning with intervening sleep.
  */
 static void do_jobctl_trap(void)
 {
 	struct signal_struct *signal = current->signal;
 	int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
 	if (current->ptrace & PT_SEIZED) {
 		if (!signal->group_stop_count &&
 		    !(signal->flags & SIGNAL_STOP_STOPPED))
 			signr = SIGTRAP;
 		WARN_ON_ONCE(!signr);
 		ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
 				 CLD_STOPPED);
 	} else {
 		WARN_ON_ONCE(!signr);
 		ptrace_stop(signr, CLD_STOPPED, 0, NULL);
 		current->exit_code = 0;
 	}
 }
 static int ptrace_signal(int signr, siginfo_t *info,
 			 struct pt_regs *regs, void *cookie)
 {
 	if (!current->ptrace)
 		return signr;
 	ptrace_signal_deliver(regs, cookie);
 	/* Let the debugger run.  */
 	ptrace_stop(signr, CLD_TRAPPED, 0, info);
 	/* We're back.  Did the debugger cancel the sig?  */
 	signr = current->exit_code;
 	if (signr == 0)
 		return signr;
 	current->exit_code = 0;
 	/*
 	 * Update the siginfo structure if the signal has
 	 * changed.  If the debugger wanted something
 	 * specific in the siginfo structure then it should
 	 * have updated *info via PTRACE_SETSIGINFO.
 	 */
 	if (signr != info->si_signo) {
 		info->si_signo = signr;
 		info->si_errno = 0;
 		info->si_code = SI_USER;
 		info->si_pid = task_pid_vnr(current->parent);
 		info->si_uid = task_uid(current->parent);
 	}
 	/* If the (new) signal is now blocked, requeue it.  */
 	if (sigismember(&current->blocked, signr)) {
 		specific_send_sig_info(signr, info, current);
 		signr = 0;
 	}
 	return signr;
 }
 int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka,
 			  struct pt_regs *regs, void *cookie)
 {
 	struct sighand_struct *sighand = current->sighand;
 	struct signal_struct *signal = current->signal;
 	int signr;
 relock:
 	/*
 	 * We'll jump back here after any time we were stopped in TASK_STOPPED.
 	 * While in TASK_STOPPED, we were considered "frozen enough".
 	 * Now that we woke up, it's crucial if we're supposed to be
 	 * frozen that we freeze now before running anything substantial.
 	 */
 	try_to_freeze();
 	spin_lock_irq(&sighand->siglock);
 	/*
 	 * Every stopped thread goes here after wakeup. Check to see if
 	 * we should notify the parent, prepare_signal(SIGCONT) encodes
 	 * the CLD_ si_code into SIGNAL_CLD_MASK bits.
 	 */
 	if (unlikely(signal->flags & SIGNAL_CLD_MASK)) {
 		struct task_struct *leader;
 		int why;
 		if (signal->flags & SIGNAL_CLD_CONTINUED)
 			why = CLD_CONTINUED;
 		else
 			why = CLD_STOPPED;
 		signal->flags &= ~SIGNAL_CLD_MASK;
 		spin_unlock_irq(&sighand->siglock);
 		/*
 		 * Notify the parent that we're continuing.  This event is
 		 * always per-process and doesn't make whole lot of sense
 		 * for ptracers, who shouldn't consume the state via
 		 * wait(2) either, but, for backward compatibility, notify
 		 * the ptracer of the group leader too unless it's gonna be
 		 * a duplicate.
 		 */
 		read_lock(&tasklist_lock);
 		do_notify_parent_cldstop(current, false, why);
 		leader = current->group_leader;
 		if (leader->ptrace && !real_parent_is_ptracer(leader))
 			do_notify_parent_cldstop(leader, true, why);
 		read_unlock(&tasklist_lock);
 		goto relock;
 	}
 	for (;;) {
 		struct k_sigaction *ka;
 		if (unlikely(current->jobctl & JOBCTL_STOP_PENDING) &&
 		    do_signal_stop(0))
 			goto relock;
 		if (unlikely(current->jobctl & JOBCTL_TRAP_MASK)) {
 			do_jobctl_trap();
 			spin_unlock_irq(&sighand->siglock);
 			goto relock;
 		}
 		signr = dequeue_signal(current, &current->blocked, info);
 		if (!signr)
 			break; /* will return 0 */
 		if (signr != SIGKILL) {
 			signr = ptrace_signal(signr, info,
 					      regs, cookie);
 			if (!signr)
 				continue;
 		}
 		ka = &sighand->action[signr-1];
 		/* Trace actually delivered signals. */
 		trace_signal_deliver(signr, info, ka);
 		if (ka->sa.sa_handler == SIG_IGN) /* Do nothing.  */
 			continue;
 		if (ka->sa.sa_handler != SIG_DFL) {
 			/* Run the handler.  */
 			*return_ka = *ka;
 			if (ka->sa.sa_flags & SA_ONESHOT)
 				ka->sa.sa_handler = SIG_DFL;
 			break; /* will return non-zero "signr" value */
 		}
 		/*
 		 * Now we are doing the default action for this signal.
 		 */
 		if (sig_kernel_ignore(signr)) /* Default is nothing. */
 			continue;
 		/*
 		 * Global init gets no signals it doesn't want.
 		 * Container-init gets no signals it doesn't want from same
 		 * container.
 		 *
 		 * Note that if global/container-init sees a sig_kernel_only()
 		 * signal here, the signal must have been generated internally
 		 * or must have come from an ancestor namespace. In either
 		 * case, the signal cannot be dropped.
 		 */
 		if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
 				!sig_kernel_only(signr))
 			continue;
 		if (sig_kernel_stop(signr)) {
 			/*
 			 * The default action is to stop all threads in
 			 * the thread group.  The job control signals
 			 * do nothing in an orphaned pgrp, but SIGSTOP
 			 * always works.  Note that siglock needs to be
 			 * dropped during the call to is_orphaned_pgrp()
 			 * because of lock ordering with tasklist_lock.
 			 * This allows an intervening SIGCONT to be posted.
 			 * We need to check for that and bail out if necessary.
 			 */
 			if (signr != SIGSTOP) {
 				spin_unlock_irq(&sighand->siglock);
 				/* signals can be posted during this window */
 				if (is_current_pgrp_orphaned())
 					goto relock;
 				spin_lock_irq(&sighand->siglock);
 			}
 			if (likely(do_signal_stop(info->si_signo))) {
 				/* It released the siglock.  */
 				goto relock;
 			}
 			/*
 			 * We didn't actually stop, due to a race
 			 * with SIGCONT or something like that.
 			 */
 			continue;
 		}
 		spin_unlock_irq(&sighand->siglock);
 		/*
 		 * Anything else is fatal, maybe with a core dump.
 		 */
 		current->flags |= PF_SIGNALED;
 		if (sig_kernel_coredump(signr)) {
 			if (print_fatal_signals)
 				print_fatal_signal(regs, info->si_signo);
 			/*
 			 * If it was able to dump core, this kills all
 			 * other threads in the group and synchronizes with
 			 * their demise.  If we lost the race with another
 			 * thread getting here, it set group_exit_code
 			 * first and our do_group_exit call below will use
 			 * that value and ignore the one we pass it.
 			 */
 			do_coredump(info->si_signo, info->si_signo, regs);
 		}
 		/*
 		 * Death signals, no core dump.
 		 */
 		do_group_exit(info->si_signo);
 		/* NOTREACHED */
 	}
 	spin_unlock_irq(&sighand->siglock);
 	return signr;
 }
 /*
  * It could be that complete_signal() picked us to notify about the
  * group-wide signal. Other threads should be notified now to take
  * the shared signals in @which since we will not.
  */
 static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
 {
 	sigset_t retarget;
 	struct task_struct *t;
 	sigandsets(&retarget, &tsk->signal->shared_pending.signal, which);
 	if (sigisemptyset(&retarget))
 		return;
 	t = tsk;
 	while_each_thread(tsk, t) {
 		if (t->flags & PF_EXITING)
 			continue;
 		if (!has_pending_signals(&retarget, &t->blocked))
 			continue;
 		/* Remove the signals this thread can handle. */
 		sigandsets(&retarget, &retarget, &t->blocked);
 		if (!signal_pending(t))
 			signal_wake_up(t, 0);
 		if (sigisemptyset(&retarget))
 			break;
 	}
 }
 void exit_signals(struct task_struct *tsk)
 {
 	int group_stop = 0;
 	sigset_t unblocked;
 	if (thread_group_empty(tsk) || signal_group_exit(tsk->signal)) {
 		tsk->flags |= PF_EXITING;
 		return;
 	}
 	spin_lock_irq(&tsk->sighand->siglock);
 	/*
 	 * From now this task is not visible for group-wide signals,
 	 * see wants_signal(), do_signal_stop().
 	 */
 	tsk->flags |= PF_EXITING;
 	if (!signal_pending(tsk))
 		goto out;
 	unblocked = tsk->blocked;
 	signotset(&unblocked);
 	retarget_shared_pending(tsk, &unblocked);
 	if (unlikely(tsk->jobctl & JOBCTL_STOP_PENDING) &&
 	    task_participate_group_stop(tsk))
 		group_stop = CLD_STOPPED;
 out:
 	spin_unlock_irq(&tsk->sighand->siglock);
 	/*
 	 * If group stop has completed, deliver the notification.  This
 	 * should always go to the real parent of the group leader.
 	 */
 	if (unlikely(group_stop)) {
 		read_lock(&tasklist_lock);
 		do_notify_parent_cldstop(tsk, false, group_stop);
 		read_unlock(&tasklist_lock);
 	}
 }
 EXPORT_SYMBOL(recalc_sigpending);
 EXPORT_SYMBOL_GPL(dequeue_signal);
 EXPORT_SYMBOL(flush_signals);
 EXPORT_SYMBOL(force_sig);
 EXPORT_SYMBOL(send_sig);
 EXPORT_SYMBOL(send_sig_info);
 EXPORT_SYMBOL(sigprocmask);
 EXPORT_SYMBOL(block_all_signals);
 EXPORT_SYMBOL(unblock_all_signals);
 /*
  * System call entry points.
  */
 /**
  *  sys_restart_syscall - restart a system call
  */
 SYSCALL_DEFINE0(restart_syscall)
 {
 	struct restart_block *restart = &current_thread_info()->restart_block;
 	return restart->fn(restart);
 }
 long do_no_restart_syscall(struct restart_block *param)
 {
 	return -EINTR;
 }
 static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
 {
 	if (signal_pending(tsk) && !thread_group_empty(tsk)) {
 		sigset_t newblocked;
 		/* A set of now blocked but previously unblocked signals. */
 		sigandnsets(&newblocked, newset, &current->blocked);
 		retarget_shared_pending(tsk, &newblocked);
 	}
 	tsk->blocked = *newset;
 	recalc_sigpending();
 }
 /**
  * set_current_blocked - change current->blocked mask
  * @newset: new mask
  *
  * It is wrong to change ->blocked directly, this helper should be used
  * to ensure the process can't miss a shared signal we are going to block.
  */
 void set_current_blocked(const sigset_t *newset)
 {
 	struct task_struct *tsk = current;
 	spin_lock_irq(&tsk->sighand->siglock);
 	__set_task_blocked(tsk, newset);
 	spin_unlock_irq(&tsk->sighand->siglock);
 }
 /*
  * This is also useful for kernel threads that want to temporarily
  * (or permanently) block certain signals.
  *
  * NOTE! Unlike the user-mode sys_sigprocmask(), the kernel
  * interface happily blocks "unblockable" signals like SIGKILL
  * and friends.
  */
 int sigprocmask(int how, sigset_t *set, sigset_t *oldset)
 {
 	struct task_struct *tsk = current;
 	sigset_t newset;
 	/* Lockless, only current can change ->blocked, never from irq */
 	if (oldset)
 		*oldset = tsk->blocked;
 	switch (how) {
 	case SIG_BLOCK:
 		sigorsets(&newset, &tsk->blocked, set);
 		break;
 	case SIG_UNBLOCK:
 		sigandnsets(&newset, &tsk->blocked, set);
 		break;
 	case SIG_SETMASK:
 		newset = *set;
 		break;
 	default:
 		return -EINVAL;
 	}
 	set_current_blocked(&newset);
 	return 0;
 }
 /**
  *  sys_rt_sigprocmask - change the list of currently blocked signals
  *  @how: whether to add, remove, or set signals
  *  @set: stores pending signals
  *  @oset: previous value of signal mask if non-null
  *  @sigsetsize: size of sigset_t type
  */
 SYSCALL_DEFINE4(rt_sigprocmask, int, how, sigset_t __user *, nset,
 		sigset_t __user *, oset, size_t, sigsetsize)
 {
 	sigset_t old_set, new_set;
 	int error;
 	/* XXX: Don't preclude handling different sized sigset_t's.  */
 	if (sigsetsize != sizeof(sigset_t))
 		return -EINVAL;
 	old_set = current->blocked;
 	if (nset) {
 		if (copy_from_user(&new_set, nset, sizeof(sigset_t)))
 			return -EFAULT;
 		sigdelsetmask(&new_set, sigmask(SIGKILL)|sigmask(SIGSTOP));
 		error = sigprocmask(how, &new_set, NULL);
 		if (error)
 			return error;
 	}
 	if (oset) {
 		if (copy_to_user(oset, &old_set, sizeof(sigset_t)))
 			return -EFAULT;
 	}
 	return 0;
 }
 long do_sigpending(void __user *set, unsigned long sigsetsize)
 {
 	long error = -EINVAL;
 	sigset_t pending;
 	if (sigsetsize > sizeof(sigset_t))
 		goto out;
 	spin_lock_irq(&current->sighand->siglock);
 	sigorsets(&pending, &current->pending.signal,
 		  &current->signal->shared_pending.signal);
 	spin_unlock_irq(&current->sighand->siglock);
 	/* Outside the lock because only this thread touches it.  */
 	sigandsets(&pending, &current->blocked, &pending);
 	error = -EFAULT;
 	if (!copy_to_user(set, &pending, sigsetsize))
 		error = 0;
 out:
 	return error;
 }
 /**
  *  sys_rt_sigpending - examine a pending signal that has been raised
  *			while blocked
  *  @set: stores pending signals
  *  @sigsetsize: size of sigset_t type or larger
  */
 SYSCALL_DEFINE2(rt_sigpending, sigset_t __user *, set, size_t, sigsetsize)
 {
 	return do_sigpending(set, sigsetsize);
 }
 #ifndef HAVE_ARCH_COPY_SIGINFO_TO_USER
 int copy_siginfo_to_user(siginfo_t __user *to, siginfo_t *from)
 {
 	int err;
 	if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
 		return -EFAULT;
 	if (from->si_code < 0)
 		return __copy_to_user(to, from, sizeof(siginfo_t))
 			? -EFAULT : 0;
 	/*
 	 * If you change siginfo_t structure, please be sure
 	 * this code is fixed accordingly.
 	 * Please remember to update the signalfd_copyinfo() function
 	 * inside fs/signalfd.c too, in case siginfo_t changes.
 	 * It should never copy any pad contained in the structure
 	 * to avoid security leaks, but must copy the generic
 	 * 3 ints plus the relevant union member.
 	 */
 	err = __put_user(from->si_signo, &to->si_signo);
 	err |= __put_user(from->si_errno, &to->si_errno);
 	err |= __put_user((short)from->si_code, &to->si_code);
 	switch (from->si_code & __SI_MASK) {
 	case __SI_KILL:
 		err |= __put_user(from->si_pid, &to->si_pid);
 		err |= __put_user(from->si_uid, &to->si_uid);
 		break;
 	case __SI_TIMER:
 		 err |= __put_user(from->si_tid, &to->si_tid);
 		 err |= __put_user(from->si_overrun, &to->si_overrun);
 		 err |= __put_user(from->si_ptr, &to->si_ptr);
 		break;
 	case __SI_POLL:
 		err |= __put_user(from->si_band, &to->si_band);
 		err |= __put_user(from->si_fd, &to->si_fd);
 		break;
 	case __SI_FAULT:
 		err |= __put_user(from->si_addr, &to->si_addr);
 #ifdef __ARCH_SI_TRAPNO
 		err |= __put_user(from->si_trapno, &to->si_trapno);
 #endif
 #ifdef BUS_MCEERR_AO
 		/*
 		 * Other callers might not initialize the si_lsb field,
 		 * so check explicitly for the right codes here.
 		 */
 		if (from->si_code == BUS_MCEERR_AR || from->si_code == BUS_MCEERR_AO)
 			err |= __put_user(from->si_addr_lsb, &to->si_addr_lsb);
 #endif
 		break;
 	case __SI_CHLD:
 		err |= __put_user(from->si_pid, &to->si_pid);
 		err |= __put_user(from->si_uid, &to->si_uid);
 		err |= __put_user(from->si_status, &to->si_status);
 		err |= __put_user(from->si_utime, &to->si_utime);
 		err |= __put_user(from->si_stime, &to->si_stime);
 		break;
 	case __SI_RT: /* This is not generated by the kernel as of now. */
 	case __SI_MESGQ: /* But this is */
 		err |= __put_user(from->si_pid, &to->si_pid);
 		err |= __put_user(from->si_uid, &to->si_uid);
 		err |= __put_user(from->si_ptr, &to->si_ptr);
 		break;
 	default: /* this is just in case for now ... */
 		err |= __put_user(from->si_pid, &to->si_pid);
 		err |= __put_user(from->si_uid, &to->si_uid);
 		break;
 	}
 	return err;
 }
 #endif
 /**
  *  do_sigtimedwait - wait for queued signals specified in @which
  *  @which: queued signals to wait for
  *  @info: if non-null, the signal's siginfo is returned here
  *  @ts: upper bound on process time suspension
  */
 int do_sigtimedwait(const sigset_t *which, siginfo_t *info,
 			const struct timespec *ts)
 {
 	struct task_struct *tsk = current;
 	long timeout = MAX_SCHEDULE_TIMEOUT;
 	sigset_t mask = *which;
 	int sig;
 	if (ts) {
 		if (!timespec_valid(ts))
 			return -EINVAL;
 		timeout = timespec_to_jiffies(ts);
 		/*
 		 * We can be close to the next tick, add another one
 		 * to ensure we will wait at least the time asked for.
 		 */
 		if (ts->tv_sec || ts->tv_nsec)
 			timeout++;
 	}
 	/*
 	 * Invert the set of allowed signals to get those we want to block.
 	 */
 	sigdelsetmask(&mask, sigmask(SIGKILL) | sigmask(SIGSTOP));
 	signotset(&mask);
 	spin_lock_irq(&tsk->sighand->siglock);
 	sig = dequeue_signal(tsk, &mask, info);
 	if (!sig && timeout) {
 		/*
 		 * None ready, temporarily unblock those we're interested
 		 * while we are sleeping in so that we'll be awakened when
 		 * they arrive. Unblocking is always fine, we can avoid
 		 * set_current_blocked().
 		 */
 		tsk->real_blocked = tsk->blocked;
 		sigandsets(&tsk->blocked, &tsk->blocked, &mask);
 		recalc_sigpending();
 		spin_unlock_irq(&tsk->sighand->siglock);
 		timeout = schedule_timeout_interruptible(timeout);
 		spin_lock_irq(&tsk->sighand->siglock);
 		__set_task_blocked(tsk, &tsk->real_blocked);
 		siginitset(&tsk->real_blocked, 0);
 		sig = dequeue_signal(tsk, &mask, info);
 	}
 	spin_unlock_irq(&tsk->sighand->siglock);
 	if (sig)
 		return sig;
 	return timeout ? -EINTR : -EAGAIN;
 }
 /**
  *  sys_rt_sigtimedwait - synchronously wait for queued signals specified
  *			in @uthese
  *  @uthese: queued signals to wait for
  *  @uinfo: if non-null, the signal's siginfo is returned here
  *  @uts: upper bound on process time suspension
  *  @sigsetsize: size of sigset_t type
  */
 SYSCALL_DEFINE4(rt_sigtimedwait, const sigset_t __user *, uthese,
 		siginfo_t __user *, uinfo, const struct timespec __user *, uts,
 		size_t, sigsetsize)
 {
 	sigset_t these;
 	struct timespec ts;
 	siginfo_t info;
 	int ret;
 	/* XXX: Don't preclude handling different sized sigset_t's.  */
 	if (sigsetsize != sizeof(sigset_t))
 		return -EINVAL;
 	if (copy_from_user(&these, uthese, sizeof(these)))
 		return -EFAULT;
 	if (uts) {
 		if (copy_from_user(&ts, uts, sizeof(ts)))
 			return -EFAULT;
 	}
 	ret = do_sigtimedwait(&these, &info, uts ? &ts : NULL);
 	if (ret > 0 && uinfo) {
 		if (copy_siginfo_to_user(uinfo, &info))
 			ret = -EFAULT;
 	}
 	return ret;
 }
 /**
  *  sys_kill - send a signal to a process
  *  @pid: the PID of the process
  *  @sig: signal to be sent
  */
 SYSCALL_DEFINE2(kill, pid_t, pid, int, sig)
 {
 	struct siginfo info;
 	info.si_signo = sig;
 	info.si_errno = 0;
 	info.si_code = SI_USER;
 	info.si_pid = task_tgid_vnr(current);
 	info.si_uid = current_uid();
 	return kill_something_info(sig, &info, pid);
 }
 static int
 do_send_specific(pid_t tgid, pid_t pid, int sig, struct siginfo *info)
 {
 	struct task_struct *p;
 	int error = -ESRCH;
 	rcu_read_lock();
 	p = find_task_by_vpid(pid);
 	if (p && (tgid <= 0 || task_tgid_vnr(p) == tgid)) {
 		error = check_kill_permission(sig, info, p);
 		/*
 		 * The null signal is a permissions and process existence
 		 * probe.  No signal is actually delivered.
 		 */
 		if (!error && sig) {
 			error = do_send_sig_info(sig, info, p, false);
 			/*
 			 * If lock_task_sighand() failed we pretend the task
 			 * dies after receiving the signal. The window is tiny,
 			 * and the signal is private anyway.
 			 */
 			if (unlikely(error == -ESRCH))
 				error = 0;
 		}
 	}
 	rcu_read_unlock();
 	return error;
 }
 static int do_tkill(pid_t tgid, pid_t pid, int sig)
 {
 	struct siginfo info;
 	info.si_signo = sig;
 	info.si_errno = 0;
 	info.si_code = SI_TKILL;
 	info.si_pid = task_tgid_vnr(current);
 	info.si_uid = current_uid();
 	return do_send_specific(tgid, pid, sig, &info);
 }
 /**
  *  sys_tgkill - send signal to one specific thread
  *  @tgid: the thread group ID of the thread
  *  @pid: the PID of the thread
  *  @sig: signal to be sent
  *
  *  This syscall also checks the @tgid and returns -ESRCH even if the PID
  *  exists but it's not belonging to the target process anymore. This
  *  method solves the problem of threads exiting and PIDs getting reused.
  */
 SYSCALL_DEFINE3(tgkill, pid_t, tgid, pid_t, pid, int, sig)
 {
 	/* This is only valid for single tasks */
 	if (pid <= 0 || tgid <= 0)
 		return -EINVAL;
 	return do_tkill(tgid, pid, sig);
 }
 /**
  *  sys_tkill - send signal to one specific task
  *  @pid: the PID of the task
  *  @sig: signal to be sent
  *
  *  Send a signal to only one task, even if it's a CLONE_THREAD task.
  */
 SYSCALL_DEFINE2(tkill, pid_t, pid, int, sig)
 {
 	/* This is only valid for single tasks */
 	if (pid <= 0)
 		return -EINVAL;
 	return do_tkill(0, pid, sig);
 }
 /**
  *  sys_rt_sigqueueinfo - send signal information to a signal
  *  @pid: the PID of the thread
  *  @sig: signal to be sent
  *  @uinfo: signal info to be sent
  */
 SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig,
 		siginfo_t __user *, uinfo)
 {
 	siginfo_t info;
 	if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
 		return -EFAULT;
 	/* Not even root can pretend to send signals from the kernel.
 	 * Nor can they impersonate a kill()/tgkill(), which adds source info.
 	 */
 	if (info.si_code >= 0 || info.si_code == SI_TKILL) {
 		/* We used to allow any < 0 si_code */
 		WARN_ON_ONCE(info.si_code < 0);
 		return -EPERM;
 	}
 	info.si_signo = sig;
 	/* POSIX.1b doesn't mention process groups.  */
 	return kill_proc_info(sig, &info, pid);
 }
 long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info)
 {
 	/* This is only valid for single tasks */
 	if (pid <= 0 || tgid <= 0)
 		return -EINVAL;
 	/* Not even root can pretend to send signals from the kernel.
 	 * Nor can they impersonate a kill()/tgkill(), which adds source info.
 	 */
 	if (info->si_code >= 0 || info->si_code == SI_TKILL) {
 		/* We used to allow any < 0 si_code */
 		WARN_ON_ONCE(info->si_code < 0);
 		return -EPERM;
 	}
 	info->si_signo = sig;
 	return do_send_specific(tgid, pid, sig, info);
 }
 SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
 		siginfo_t __user *, uinfo)
 {
 	siginfo_t info;
 	if (copy_from_user(&info, uinfo, sizeof(siginfo_t)))
 		return -EFAULT;
 	return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
 }
 int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
 {
 	struct task_struct *t = current;
 	struct k_sigaction *k;
 	sigset_t mask;
 	if (!valid_signal(sig) || sig < 1 || (act && sig_kernel_only(sig)))
 		return -EINVAL;
 	k = &t->sighand->action[sig-1];
 	spin_lock_irq(&current->sighand->siglock);
 	if (oact)
 		*oact = *k;
 	if (act) {
 		sigdelsetmask(&act->sa.sa_mask,
 			      sigmask(SIGKILL) | sigmask(SIGSTOP));
 		*k = *act;
 		/*
 		 * POSIX 3.3.1.3:
 		 *  "Setting a signal action to SIG_IGN for a signal that is
 		 *   pending shall cause the pending signal to be discarded,
 		 *   whether or not it is blocked."
 		 *
 		 *  "Setting a signal action to SIG_DFL for a signal that is
 		 *   pending and whose default action is to ignore the signal
 		 *   (for example, SIGCHLD), shall cause the pending signal to
 		 *   be discarded, whether or not it is blocked"
 		 */
 		if (sig_handler_ignored(sig_handler(t, sig), sig)) {
 			sigemptyset(&mask);
 			sigaddset(&mask, sig);
 			rm_from_queue_full(&mask, &t->signal->shared_pending);
 			do {
 				rm_from_queue_full(&mask, &t->pending);
 				t = next_thread(t);
 			} while (t != current);
 		}
 	}
 	spin_unlock_irq(&current->sighand->siglock);
 	return 0;
 }
 int
 do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
 {
 	stack_t oss;
 	int error;
 	oss.ss_sp = (void __user *) current->sas_ss_sp;
 	oss.ss_size = current->sas_ss_size;
 	oss.ss_flags = sas_ss_flags(sp);
 	if (uss) {
 		void __user *ss_sp;
 		size_t ss_size;
 		int ss_flags;
 		error = -EFAULT;
 		if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
 			goto out;
 		error = __get_user(ss_sp, &uss->ss_sp) |
 			__get_user(ss_flags, &uss->ss_flags) |
 			__get_user(ss_size, &uss->ss_size);
 		if (error)
 			goto out;
 		error = -EPERM;
 		if (on_sig_stack(sp))
 			goto out;
 		error = -EINVAL;
 		/*
 		 * Note - this code used to test ss_flags incorrectly:
 		 *  	  old code may have been written using ss_flags==0
 		 *	  to mean ss_flags==SS_ONSTACK (as this was the only
 		 *	  way that worked) - this fix preserves that older
 		 *	  mechanism.
 		 */
 		if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
 			goto out;
 		if (ss_flags == SS_DISABLE) {
 			ss_size = 0;
 			ss_sp = NULL;
 		} else {
 			error = -ENOMEM;
 			if (ss_size < MINSIGSTKSZ)
 				goto out;
 		}
 		current->sas_ss_sp = (unsigned long) ss_sp;
 		current->sas_ss_size = ss_size;
 	}
 	error = 0;
 	if (uoss) {
 		error = -EFAULT;
 		if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
 			goto out;
 		error = __put_user(oss.ss_sp, &uoss->ss_sp) |
 			__put_user(oss.ss_size, &uoss->ss_size) |
 			__put_user(oss.ss_flags, &uoss->ss_flags);
 	}
 out:
 	return error;
 }
 #ifdef __ARCH_WANT_SYS_SIGPENDING
 /**
  *  sys_sigpending - examine pending signals
  *  @set: where mask of pending signal is returned
  */
 SYSCALL_DEFINE1(sigpending, old_sigset_t __user *, set)
 {
 	return do_sigpending(set, sizeof(*set));
 }
 #endif
 #ifdef __ARCH_WANT_SYS_SIGPROCMASK
 /**
  *  sys_sigprocmask - examine and change blocked signals
  *  @how: whether to add, remove, or set signals
  *  @nset: signals to add or remove (if non-null)
  *  @oset: previous value of signal mask if non-null
  *
  * Some platforms have their own version with special arguments;
  * others support only sys_rt_sigprocmask.
  */
 SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, nset,
 		old_sigset_t __user *, oset)
 {
 	old_sigset_t old_set, new_set;
 	sigset_t new_blocked;
 	old_set = current->blocked.sig[0];
 	if (nset) {
 		if (copy_from_user(&new_set, nset, sizeof(*nset)))
 			return -EFAULT;
 		new_set &= ~(sigmask(SIGKILL) | sigmask(SIGSTOP));
 		new_blocked = current->blocked;
 		switch (how) {
 		case SIG_BLOCK:
 			sigaddsetmask(&new_blocked, new_set);
 			break;
 		case SIG_UNBLOCK:
 			sigdelsetmask(&new_blocked, new_set);
 			break;
 		case SIG_SETMASK:
 			new_blocked.sig[0] = new_set;
 			break;
 		default:
 			return -EINVAL;
 		}
 		set_current_blocked(&new_blocked);
 	}
 	if (oset) {
 		if (copy_to_user(oset, &old_set, sizeof(*oset)))
 			return -EFAULT;
 	}
 	return 0;
 }
 #endif /* __ARCH_WANT_SYS_SIGPROCMASK */
 #ifdef __ARCH_WANT_SYS_RT_SIGACTION
 /**
  *  sys_rt_sigaction - alter an action taken by a process
  *  @sig: signal to be sent
  *  @act: new sigaction
  *  @oact: used to save the previous sigaction
  *  @sigsetsize: size of sigset_t type
  */
 SYSCALL_DEFINE4(rt_sigaction, int, sig,
 		const struct sigaction __user *, act,
 		struct sigaction __user *, oact,
 		size_t, sigsetsize)
 {
 	struct k_sigaction new_sa, old_sa;
 	int ret = -EINVAL;
 	/* XXX: Don't preclude handling different sized sigset_t's.  */
 	if (sigsetsize != sizeof(sigset_t))
 		goto out;
 	if (act) {
 		if (copy_from_user(&new_sa.sa, act, sizeof(new_sa.sa)))
 			return -EFAULT;
 	}
 	ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
 	if (!ret && oact) {
 		if (copy_to_user(oact, &old_sa.sa, sizeof(old_sa.sa)))
 			return -EFAULT;
 	}
 out:
 	return ret;
 }
 #endif /* __ARCH_WANT_SYS_RT_SIGACTION */
 #ifdef __ARCH_WANT_SYS_SGETMASK
 /*
  * For backwards compatibility.  Functionality superseded by sigprocmask.
  */
 SYSCALL_DEFINE0(sgetmask)
 {
 	/* SMP safe */
 	return current->blocked.sig[0];
 }
 SYSCALL_DEFINE1(ssetmask, int, newmask)
 {
 	int old;
 	spin_lock_irq(&current->sighand->siglock);
 	old = current->blocked.sig[0];
 	siginitset(&current->blocked, newmask & ~(sigmask(SIGKILL)|
 						  sigmask(SIGSTOP)));
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
 	return old;
 }
 #endif /* __ARCH_WANT_SGETMASK */
 #ifdef __ARCH_WANT_SYS_SIGNAL
 /*
  * For backwards compatibility.  Functionality superseded by sigaction.
  */
 SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
 {
 	struct k_sigaction new_sa, old_sa;
 	int ret;
 	new_sa.sa.sa_handler = handler;
 	new_sa.sa.sa_flags = SA_ONESHOT | SA_NOMASK;
 	sigemptyset(&new_sa.sa.sa_mask);
 	ret = do_sigaction(sig, &new_sa, &old_sa);
 	return ret ? ret : (unsigned long)old_sa.sa.sa_handler;
 }
 #endif /* __ARCH_WANT_SYS_SIGNAL */
 #ifdef __ARCH_WANT_SYS_PAUSE
 SYSCALL_DEFINE0(pause)
 {
 	while (!signal_pending(current)) {
 		current->state = TASK_INTERRUPTIBLE;
 		schedule();
 	}
 	return -ERESTARTNOHAND;
 }
 #endif
 #ifdef __ARCH_WANT_SYS_RT_SIGSUSPEND
 /**
  *  sys_rt_sigsuspend - replace the signal mask for a value with the
  *	@unewset value until a signal is received
  *  @unewset: new signal mask value
  *  @sigsetsize: size of sigset_t type
  */
 SYSCALL_DEFINE2(rt_sigsuspend, sigset_t __user *, unewset, size_t, sigsetsize)
 {
 	sigset_t newset;
 	/* XXX: Don't preclude handling different sized sigset_t's.  */
 	if (sigsetsize != sizeof(sigset_t))
 		return -EINVAL;
 	if (copy_from_user(&newset, unewset, sizeof(newset)))
 		return -EFAULT;
 	sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
 	spin_lock_irq(&current->sighand->siglock);
 	current->saved_sigmask = current->blocked;
 	current->blocked = newset;
 	recalc_sigpending();
 	spin_unlock_irq(&current->sighand->siglock);
 	current->state = TASK_INTERRUPTIBLE;
 	schedule();
 	set_restore_sigmask();
 	return -ERESTARTNOHAND;
 }
 #endif /* __ARCH_WANT_SYS_RT_SIGSUSPEND */
 __attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma)
 {
 	return NULL;
 }
 void __init signals_init(void)
 {
 	sigqueue_cachep = KMEM_CACHE(sigqueue, SLAB_PANIC);
 }
 #ifdef CONFIG_KGDB_KDB
 #include <linux/kdb.h>
 /*
  * kdb_send_sig_info - Allows kdb to send signals without exposing
  * signal internals.  This function checks if the required locks are
  * available before calling the main signal code, to avoid kdb
  * deadlocks.
  */
 void
 kdb_send_sig_info(struct task_struct *t, struct siginfo *info)
 {
 	static struct task_struct *kdb_prev_t;
 	int sig, new_t;
 	if (!spin_trylock(&t->sighand->siglock)) {
 		kdb_printf("Can't do kill command now.\n"
 			   "The sigmask lock is held somewhere else in "
 			   "kernel, try again later\n");
 		return;
 	}
 	spin_unlock(&t->sighand->siglock);
 	new_t = kdb_prev_t != t;
 	kdb_prev_t = t;
 	if (t->state != TASK_RUNNING && new_t) {
 		kdb_printf("Process is not RUNNING, sending a signal from "
 			   "kdb risks deadlock\n"
 			   "on the run queue locks. "
 			   "The signal has _not_ been sent.\n"
 			   "Reissue the kill command if you want to risk "
 			   "the deadlock.\n");
 		return;
 	}
 	sig = info->si_signo;
 	if (send_sig_info(sig, info, t))
 		kdb_printf("Fail to deliver Signal %d to process %d.\n",
 			   sig, t->pid);
 	else
 		kdb_printf("Signal %d is sent to process %d.\n", sig, t->pid);
 }
 #endif	/* CONFIG_KGDB_KDB */

1	#ifndef _LINUX_SCHED_H	1	#ifndef _LINUX_SCHED_H
2	#define _LINUX_SCHED_H	2	#define _LINUX_SCHED_H
3		3
4	/*	4	/*
5	* cloning flags:	5	* cloning flags:
6	*/	6	*/
7	#define CSIGNAL 0x000000ff /* signal mask to be sent at exit */	7	#define CSIGNAL 0x000000ff /* signal mask to be sent at exit */
8	#define CLONE_VM 0x00000100 /* set if VM shared between processes */	8	#define CLONE_VM 0x00000100 /* set if VM shared between processes */
9	#define CLONE_FS 0x00000200 /* set if fs info shared between processes */	9	#define CLONE_FS 0x00000200 /* set if fs info shared between processes */
10	#define CLONE_FILES 0x00000400 /* set if open files shared between processes */	10	#define CLONE_FILES 0x00000400 /* set if open files shared between processes */
11	#define CLONE_SIGHAND 0x00000800 /* set if signal handlers and blocked signals shared */	11	#define CLONE_SIGHAND 0x00000800 /* set if signal handlers and blocked signals shared */
12	#define CLONE_PTRACE 0x00002000 /* set if we want to let tracing continue on the child too */	12	#define CLONE_PTRACE 0x00002000 /* set if we want to let tracing continue on the child too */
13	#define CLONE_VFORK 0x00004000 /* set if the parent wants the child to wake it up on mm_release */	13	#define CLONE_VFORK 0x00004000 /* set if the parent wants the child to wake it up on mm_release */
14	#define CLONE_PARENT 0x00008000 /* set if we want to have the same parent as the cloner */	14	#define CLONE_PARENT 0x00008000 /* set if we want to have the same parent as the cloner */
15	#define CLONE_THREAD 0x00010000 /* Same thread group? */	15	#define CLONE_THREAD 0x00010000 /* Same thread group? */
16	#define CLONE_NEWNS 0x00020000 /* New namespace group? */	16	#define CLONE_NEWNS 0x00020000 /* New namespace group? */
17	#define CLONE_SYSVSEM 0x00040000 /* share system V SEM_UNDO semantics */	17	#define CLONE_SYSVSEM 0x00040000 /* share system V SEM_UNDO semantics */
18	#define CLONE_SETTLS 0x00080000 /* create a new TLS for the child */	18	#define CLONE_SETTLS 0x00080000 /* create a new TLS for the child */
19	#define CLONE_PARENT_SETTID 0x00100000 /* set the TID in the parent */	19	#define CLONE_PARENT_SETTID 0x00100000 /* set the TID in the parent */
20	#define CLONE_CHILD_CLEARTID 0x00200000 /* clear the TID in the child */	20	#define CLONE_CHILD_CLEARTID 0x00200000 /* clear the TID in the child */
21	#define CLONE_DETACHED 0x00400000 /* Unused, ignored */	21	#define CLONE_DETACHED 0x00400000 /* Unused, ignored */
22	#define CLONE_UNTRACED 0x00800000 /* set if the tracing process can't force CLONE_PTRACE on this clone */	22	#define CLONE_UNTRACED 0x00800000 /* set if the tracing process can't force CLONE_PTRACE on this clone */
23	#define CLONE_CHILD_SETTID 0x01000000 /* set the TID in the child */	23	#define CLONE_CHILD_SETTID 0x01000000 /* set the TID in the child */
24	/* 0x02000000 was previously the unused CLONE_STOPPED (Start in stopped state)	24	/* 0x02000000 was previously the unused CLONE_STOPPED (Start in stopped state)
25	and is now available for re-use. */	25	and is now available for re-use. */
26	#define CLONE_NEWUTS 0x04000000 /* New utsname group? */	26	#define CLONE_NEWUTS 0x04000000 /* New utsname group? */
27	#define CLONE_NEWIPC 0x08000000 /* New ipcs */	27	#define CLONE_NEWIPC 0x08000000 /* New ipcs */
28	#define CLONE_NEWUSER 0x10000000 /* New user namespace */	28	#define CLONE_NEWUSER 0x10000000 /* New user namespace */
29	#define CLONE_NEWPID 0x20000000 /* New pid namespace */	29	#define CLONE_NEWPID 0x20000000 /* New pid namespace */
30	#define CLONE_NEWNET 0x40000000 /* New network namespace */	30	#define CLONE_NEWNET 0x40000000 /* New network namespace */
31	#define CLONE_IO 0x80000000 /* Clone io context */	31	#define CLONE_IO 0x80000000 /* Clone io context */
32		32
33	/*	33	/*
34	* Scheduling policies	34	* Scheduling policies
35	*/	35	*/
36	#define SCHED_NORMAL 0	36	#define SCHED_NORMAL 0
37	#define SCHED_FIFO 1	37	#define SCHED_FIFO 1
38	#define SCHED_RR 2	38	#define SCHED_RR 2
39	#define SCHED_BATCH 3	39	#define SCHED_BATCH 3
40	/* SCHED_ISO: reserved but not implemented yet */	40	/* SCHED_ISO: reserved but not implemented yet */