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kernel/kthread.c
34.5 KB
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// SPDX-License-Identifier: GPL-2.0-only |
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/* Kernel thread helper functions. * Copyright (C) 2004 IBM Corporation, Rusty Russell. * |
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* Creation is done via kthreadd, so that we get a clean environment |
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* even if we're invoked from userspace (think modprobe, hotplug cpu, * etc.). */ |
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#include <uapi/linux/sched/types.h> |
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#include <linux/sched.h> |
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#include <linux/sched/task.h> |
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#include <linux/kthread.h> #include <linux/completion.h> #include <linux/err.h> |
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#include <linux/cgroup.h> |
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#include <linux/cpuset.h> |
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#include <linux/unistd.h> #include <linux/file.h> |
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#include <linux/export.h> |
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#include <linux/mutex.h> |
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#include <linux/slab.h> #include <linux/freezer.h> |
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#include <linux/ptrace.h> |
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#include <linux/uaccess.h> |
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#include <linux/numa.h> |
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#include <trace/events/sched.h> |
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|
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static DEFINE_SPINLOCK(kthread_create_lock); static LIST_HEAD(kthread_create_list); struct task_struct *kthreadd_task; |
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struct kthread_create_info { |
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/* Information passed to kthread() from kthreadd. */ |
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int (*threadfn)(void *data); void *data; |
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int node; |
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|
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/* Result passed back to kthread_create() from kthreadd. */ |
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struct task_struct *result; |
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struct completion *done; |
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|
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struct list_head list; |
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}; |
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struct kthread { |
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unsigned long flags; unsigned int cpu; |
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void *data; |
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struct completion parked; |
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struct completion exited; |
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#ifdef CONFIG_BLK_CGROUP |
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struct cgroup_subsys_state *blkcg_css; #endif |
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}; |
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enum KTHREAD_BITS { KTHREAD_IS_PER_CPU = 0, KTHREAD_SHOULD_STOP, KTHREAD_SHOULD_PARK, |
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}; |
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static inline void set_kthread_struct(void *kthread) { /* * We abuse ->set_child_tid to avoid the new member and because it * can't be wrongly copied by copy_process(). We also rely on fact * that the caller can't exec, so PF_KTHREAD can't be cleared. */ current->set_child_tid = (__force void __user *)kthread; } |
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static inline struct kthread *to_kthread(struct task_struct *k) { |
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WARN_ON(!(k->flags & PF_KTHREAD)); return (__force void *)k->set_child_tid; |
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} |
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void free_kthread_struct(struct task_struct *k) { |
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struct kthread *kthread; |
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/* * Can be NULL if this kthread was created by kernel_thread() * or if kmalloc() in kthread() failed. */ |
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kthread = to_kthread(k); |
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#ifdef CONFIG_BLK_CGROUP |
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WARN_ON_ONCE(kthread && kthread->blkcg_css); #endif kfree(kthread); |
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} |
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/** * kthread_should_stop - should this kthread return now? * |
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* When someone calls kthread_stop() on your kthread, it will be woken |
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* and this will return true. You should then return, and your return * value will be passed through to kthread_stop(). */ |
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bool kthread_should_stop(void) |
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{ |
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return test_bit(KTHREAD_SHOULD_STOP, &to_kthread(current)->flags); |
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} EXPORT_SYMBOL(kthread_should_stop); |
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bool __kthread_should_park(struct task_struct *k) { return test_bit(KTHREAD_SHOULD_PARK, &to_kthread(k)->flags); } EXPORT_SYMBOL_GPL(__kthread_should_park); |
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/** |
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* kthread_should_park - should this kthread park now? * * When someone calls kthread_park() on your kthread, it will be woken * and this will return true. You should then do the necessary * cleanup and call kthread_parkme() * * Similar to kthread_should_stop(), but this keeps the thread alive * and in a park position. kthread_unpark() "restarts" the thread and * calls the thread function again. */ bool kthread_should_park(void) { |
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return __kthread_should_park(current); |
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} |
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EXPORT_SYMBOL_GPL(kthread_should_park); |
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/** |
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* kthread_freezable_should_stop - should this freezable kthread return now? * @was_frozen: optional out parameter, indicates whether %current was frozen * * kthread_should_stop() for freezable kthreads, which will enter * refrigerator if necessary. This function is safe from kthread_stop() / * freezer deadlock and freezable kthreads should use this function instead * of calling try_to_freeze() directly. */ bool kthread_freezable_should_stop(bool *was_frozen) { bool frozen = false; might_sleep(); if (unlikely(freezing(current))) frozen = __refrigerator(true); if (was_frozen) *was_frozen = frozen; return kthread_should_stop(); } EXPORT_SYMBOL_GPL(kthread_freezable_should_stop); /** |
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* kthread_data - return data value specified on kthread creation * @task: kthread task in question * * Return the data value specified when kthread @task was created. * The caller is responsible for ensuring the validity of @task when * calling this function. */ void *kthread_data(struct task_struct *task) { return to_kthread(task)->data; } |
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/** |
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* kthread_probe_data - speculative version of kthread_data() |
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* @task: possible kthread task in question * * @task could be a kthread task. Return the data value specified when it * was created if accessible. If @task isn't a kthread task or its data is * inaccessible for any reason, %NULL is returned. This function requires * that @task itself is safe to dereference. */ |
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void *kthread_probe_data(struct task_struct *task) |
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{ struct kthread *kthread = to_kthread(task); void *data = NULL; probe_kernel_read(&data, &kthread->data, sizeof(data)); return data; } |
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static void __kthread_parkme(struct kthread *self) { |
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for (;;) { |
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/* * TASK_PARKED is a special state; we must serialize against * possible pending wakeups to avoid store-store collisions on * task->state. * * Such a collision might possibly result in the task state * changin from TASK_PARKED and us failing the * wait_task_inactive() in kthread_park(). */ set_special_state(TASK_PARKED); |
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if (!test_bit(KTHREAD_SHOULD_PARK, &self->flags)) break; |
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|
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/* * Thread is going to call schedule(), do not preempt it, * or the caller of kthread_park() may spend more time in * wait_task_inactive(). */ preempt_disable(); |
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complete(&self->parked); |
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schedule_preempt_disabled(); preempt_enable(); |
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} |
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__set_current_state(TASK_RUNNING); } void kthread_parkme(void) { __kthread_parkme(to_kthread(current)); } |
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EXPORT_SYMBOL_GPL(kthread_parkme); |
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|
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static int kthread(void *_create) { |
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/* Copy data: it's on kthread's stack */ |
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struct kthread_create_info *create = _create; |
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int (*threadfn)(void *data) = create->threadfn; void *data = create->data; |
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struct completion *done; |
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struct kthread *self; |
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int ret; |
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self = kzalloc(sizeof(*self), GFP_KERNEL); |
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set_kthread_struct(self); |
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|
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/* If user was SIGKILLed, I release the structure. */ done = xchg(&create->done, NULL); if (!done) { kfree(create); do_exit(-EINTR); } |
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if (!self) { create->result = ERR_PTR(-ENOMEM); complete(done); do_exit(-ENOMEM); } |
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self->data = data; init_completion(&self->exited); init_completion(&self->parked); current->vfork_done = &self->exited; |
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/* OK, tell user we're spawned, wait for stop or wakeup */ |
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__set_current_state(TASK_UNINTERRUPTIBLE); |
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create->result = current; |
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/* * Thread is going to call schedule(), do not preempt it, * or the creator may spend more time in wait_task_inactive(). */ preempt_disable(); |
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complete(done); |
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schedule_preempt_disabled(); preempt_enable(); |
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|
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ret = -EINTR; |
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if (!test_bit(KTHREAD_SHOULD_STOP, &self->flags)) { |
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cgroup_kthread_ready(); |
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__kthread_parkme(self); |
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ret = threadfn(data); } |
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do_exit(ret); |
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} |
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/* called from do_fork() to get node information for about to be created task */ int tsk_fork_get_node(struct task_struct *tsk) { #ifdef CONFIG_NUMA if (tsk == kthreadd_task) return tsk->pref_node_fork; #endif |
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return NUMA_NO_NODE; |
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} |
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static void create_kthread(struct kthread_create_info *create) |
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{ |
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int pid; |
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#ifdef CONFIG_NUMA current->pref_node_fork = create->node; #endif |
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/* We want our own signal handler (we take no signals by default). */ pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD); |
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if (pid < 0) { |
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/* If user was SIGKILLed, I release the structure. */ struct completion *done = xchg(&create->done, NULL); if (!done) { kfree(create); return; } |
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create->result = ERR_PTR(pid); |
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complete(done); |
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} |
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} |
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static __printf(4, 0) struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data), |
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void *data, int node, const char namefmt[], va_list args) |
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{ |
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DECLARE_COMPLETION_ONSTACK(done); struct task_struct *task; struct kthread_create_info *create = kmalloc(sizeof(*create), GFP_KERNEL); if (!create) return ERR_PTR(-ENOMEM); create->threadfn = threadfn; create->data = data; create->node = node; create->done = &done; |
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spin_lock(&kthread_create_lock); |
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list_add_tail(&create->list, &kthread_create_list); |
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spin_unlock(&kthread_create_lock); |
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wake_up_process(kthreadd_task); |
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/* * Wait for completion in killable state, for I might be chosen by * the OOM killer while kthreadd is trying to allocate memory for * new kernel thread. */ if (unlikely(wait_for_completion_killable(&done))) { /* * If I was SIGKILLed before kthreadd (or new kernel thread) * calls complete(), leave the cleanup of this structure to * that thread. */ if (xchg(&create->done, NULL)) |
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return ERR_PTR(-EINTR); |
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/* * kthreadd (or new kernel thread) will call complete() * shortly. */ wait_for_completion(&done); } task = create->result; if (!IS_ERR(task)) { |
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static const struct sched_param param = { .sched_priority = 0 }; |
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char name[TASK_COMM_LEN]; |
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|
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/* * task is already visible to other tasks, so updating * COMM must be protected. */ vsnprintf(name, sizeof(name), namefmt, args); set_task_comm(task, name); |
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/* * root may have changed our (kthreadd's) priority or CPU mask. * The kernel thread should not inherit these properties. */ |
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sched_setscheduler_nocheck(task, SCHED_NORMAL, ¶m); set_cpus_allowed_ptr(task, cpu_all_mask); |
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} |
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kfree(create); return task; |
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} |
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/** * kthread_create_on_node - create a kthread. * @threadfn: the function to run until signal_pending(current). * @data: data ptr for @threadfn. * @node: task and thread structures for the thread are allocated on this node * @namefmt: printf-style name for the thread. * * Description: This helper function creates and names a kernel * thread. The thread will be stopped: use wake_up_process() to start * it. See also kthread_run(). The new thread has SCHED_NORMAL policy and * is affine to all CPUs. * * If thread is going to be bound on a particular cpu, give its node * in @node, to get NUMA affinity for kthread stack, or else give NUMA_NO_NODE. * When woken, the thread will run @threadfn() with @data as its * argument. @threadfn() can either call do_exit() directly if it is a * standalone thread for which no one will call kthread_stop(), or * return when 'kthread_should_stop()' is true (which means * kthread_stop() has been called). The return value should be zero * or a negative error number; it will be passed to kthread_stop(). * * Returns a task_struct or ERR_PTR(-ENOMEM) or ERR_PTR(-EINTR). */ struct task_struct *kthread_create_on_node(int (*threadfn)(void *data), void *data, int node, const char namefmt[], ...) { struct task_struct *task; va_list args; va_start(args, namefmt); task = __kthread_create_on_node(threadfn, data, node, namefmt, args); va_end(args); return task; } |
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EXPORT_SYMBOL(kthread_create_on_node); |
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|
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static void __kthread_bind_mask(struct task_struct *p, const struct cpumask *mask, long state) |
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{ |
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unsigned long flags; |
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if (!wait_task_inactive(p, state)) { WARN_ON(1); return; } |
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|
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/* It's safe because the task is inactive. */ |
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raw_spin_lock_irqsave(&p->pi_lock, flags); do_set_cpus_allowed(p, mask); |
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p->flags |= PF_NO_SETAFFINITY; |
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raw_spin_unlock_irqrestore(&p->pi_lock, flags); } static void __kthread_bind(struct task_struct *p, unsigned int cpu, long state) { __kthread_bind_mask(p, cpumask_of(cpu), state); } void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask) { __kthread_bind_mask(p, mask, TASK_UNINTERRUPTIBLE); |
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} |
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/** |
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* kthread_bind - bind a just-created kthread to a cpu. * @p: thread created by kthread_create(). * @cpu: cpu (might not be online, must be possible) for @k to run on. * * Description: This function is equivalent to set_cpus_allowed(), * except that @cpu doesn't need to be online, and the thread must be * stopped (i.e., just returned from kthread_create()). */ void kthread_bind(struct task_struct *p, unsigned int cpu) { |
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__kthread_bind(p, cpu, TASK_UNINTERRUPTIBLE); |
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} EXPORT_SYMBOL(kthread_bind); /** |
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* kthread_create_on_cpu - Create a cpu bound kthread * @threadfn: the function to run until signal_pending(current). * @data: data ptr for @threadfn. * @cpu: The cpu on which the thread should be bound, * @namefmt: printf-style name for the thread. Format is restricted * to "name.*%u". Code fills in cpu number. * * Description: This helper function creates and names a kernel thread * The thread will be woken and put into park mode. */ struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data), void *data, unsigned int cpu, const char *namefmt) { struct task_struct *p; |
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p = kthread_create_on_node(threadfn, data, cpu_to_node(cpu), namefmt, |
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cpu); if (IS_ERR(p)) return p; |
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kthread_bind(p, cpu); /* CPU hotplug need to bind once again when unparking the thread. */ |
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set_bit(KTHREAD_IS_PER_CPU, &to_kthread(p)->flags); to_kthread(p)->cpu = cpu; |
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return p; } |
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/** * kthread_unpark - unpark a thread created by kthread_create(). * @k: thread created by kthread_create(). * * Sets kthread_should_park() for @k to return false, wakes it, and * waits for it to return. If the thread is marked percpu then its * bound to the cpu again. */ void kthread_unpark(struct task_struct *k) |
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{ |
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struct kthread *kthread = to_kthread(k); |
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/* |
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* Newly created kthread was parked when the CPU was offline. * The binding was lost and we need to set it again. |
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470 |
*/ |
85f1abe00 kthread, sched/wa... |
471 472 473 474 |
if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags)) __kthread_bind(k, kthread->cpu, TASK_PARKED); clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags); |
1cef1150e kthread, sched/co... |
475 476 477 |
/* * __kthread_parkme() will either see !SHOULD_PARK or get the wakeup. */ |
85f1abe00 kthread, sched/wa... |
478 |
wake_up_state(k, TASK_PARKED); |
f2530dc71 kthread: Prevent ... |
479 |
} |
18896451e kthread: export k... |
480 |
EXPORT_SYMBOL_GPL(kthread_unpark); |
2a1d44601 kthread: Implemen... |
481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 |
/** * kthread_park - park a thread created by kthread_create(). * @k: thread created by kthread_create(). * * Sets kthread_should_park() for @k to return true, wakes it, and * waits for it to return. This can also be called after kthread_create() * instead of calling wake_up_process(): the thread will park without * calling threadfn(). * * Returns 0 if the thread is parked, -ENOSYS if the thread exited. * If called by the kthread itself just the park bit is set. */ int kthread_park(struct task_struct *k) { |
cf380a4a9 kthread: Don't us... |
496 497 498 499 |
struct kthread *kthread = to_kthread(k); if (WARN_ON(k->flags & PF_EXITING)) return -ENOSYS; |
f83ee19be kthread: Simplify... |
500 501 |
if (WARN_ON_ONCE(test_bit(KTHREAD_SHOULD_PARK, &kthread->flags))) return -EBUSY; |
85f1abe00 kthread, sched/wa... |
502 503 504 |
set_bit(KTHREAD_SHOULD_PARK, &kthread->flags); if (k != current) { wake_up_process(k); |
1cef1150e kthread, sched/co... |
505 506 507 508 |
/* * Wait for __kthread_parkme() to complete(), this means we * _will_ have TASK_PARKED and are about to call schedule(). */ |
85f1abe00 kthread, sched/wa... |
509 |
wait_for_completion(&kthread->parked); |
1cef1150e kthread, sched/co... |
510 511 512 513 514 |
/* * Now wait for that schedule() to complete and the task to * get scheduled out. */ WARN_ON_ONCE(!wait_task_inactive(k, TASK_PARKED)); |
2a1d44601 kthread: Implemen... |
515 |
} |
cf380a4a9 kthread: Don't us... |
516 517 |
return 0; |
2a1d44601 kthread: Implemen... |
518 |
} |
18896451e kthread: export k... |
519 |
EXPORT_SYMBOL_GPL(kthread_park); |
2a1d44601 kthread: Implemen... |
520 521 |
/** |
9e37bd301 [PATCH] kthread: ... |
522 523 524 525 |
* kthread_stop - stop a thread created by kthread_create(). * @k: thread created by kthread_create(). * * Sets kthread_should_stop() for @k to return true, wakes it, and |
9ae260270 update the commen... |
526 527 528 529 530 531 |
* waits for it to exit. This can also be called after kthread_create() * instead of calling wake_up_process(): the thread will exit without * calling threadfn(). * * If threadfn() may call do_exit() itself, the caller must ensure * task_struct can't go away. |
9e37bd301 [PATCH] kthread: ... |
532 533 534 535 |
* * Returns the result of threadfn(), or %-EINTR if wake_up_process() * was never called. */ |
1da177e4c Linux-2.6.12-rc2 |
536 537 |
int kthread_stop(struct task_struct *k) { |
b5c5442bb kthread: kill tas... |
538 |
struct kthread *kthread; |
1da177e4c Linux-2.6.12-rc2 |
539 |
int ret; |
0a16b6075 tracing, sched: L... |
540 |
trace_sched_kthread_stop(k); |
b5c5442bb kthread: kill tas... |
541 542 |
get_task_struct(k); |
efb29fbfa kthread: Don't us... |
543 544 |
kthread = to_kthread(k); set_bit(KTHREAD_SHOULD_STOP, &kthread->flags); |
cf380a4a9 kthread: Don't us... |
545 |
kthread_unpark(k); |
efb29fbfa kthread: Don't us... |
546 547 |
wake_up_process(k); wait_for_completion(&kthread->exited); |
63706172f kthreads: rework ... |
548 |
ret = k->exit_code; |
1da177e4c Linux-2.6.12-rc2 |
549 |
put_task_struct(k); |
0a16b6075 tracing, sched: L... |
550 |
|
b5c5442bb kthread: kill tas... |
551 |
trace_sched_kthread_stop_ret(ret); |
1da177e4c Linux-2.6.12-rc2 |
552 553 |
return ret; } |
52e92e578 [PATCH] remove ke... |
554 |
EXPORT_SYMBOL(kthread_stop); |
1da177e4c Linux-2.6.12-rc2 |
555 |
|
e804a4a4d kthread: silence ... |
556 |
int kthreadd(void *unused) |
1da177e4c Linux-2.6.12-rc2 |
557 |
{ |
73c279927 kthread: don't de... |
558 |
struct task_struct *tsk = current; |
1da177e4c Linux-2.6.12-rc2 |
559 |
|
e804a4a4d kthread: silence ... |
560 |
/* Setup a clean context for our children to inherit. */ |
73c279927 kthread: don't de... |
561 |
set_task_comm(tsk, "kthreadd"); |
10ab825bd change kernel thr... |
562 |
ignore_signals(tsk); |
1a2142afa cpumask: remove d... |
563 |
set_cpus_allowed_ptr(tsk, cpu_all_mask); |
aee4faa49 kthread: use N_ME... |
564 |
set_mems_allowed(node_states[N_MEMORY]); |
73c279927 kthread: don't de... |
565 |
|
34b087e48 freezer: kill unu... |
566 |
current->flags |= PF_NOFREEZE; |
77f88796c cgroup, kthread: ... |
567 |
cgroup_init_kthreadd(); |
73c279927 kthread: don't de... |
568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 |
for (;;) { set_current_state(TASK_INTERRUPTIBLE); if (list_empty(&kthread_create_list)) schedule(); __set_current_state(TASK_RUNNING); spin_lock(&kthread_create_lock); while (!list_empty(&kthread_create_list)) { struct kthread_create_info *create; create = list_entry(kthread_create_list.next, struct kthread_create_info, list); list_del_init(&create->list); spin_unlock(&kthread_create_lock); create_kthread(create); spin_lock(&kthread_create_lock); } spin_unlock(&kthread_create_lock); } return 0; } |
b56c0d893 kthread: implemen... |
593 |
|
3989144f8 kthread: kthread ... |
594 |
void __kthread_init_worker(struct kthread_worker *worker, |
4f32e9b1f kthread_work: mak... |
595 596 597 |
const char *name, struct lock_class_key *key) { |
dbf52682c kthread: better s... |
598 |
memset(worker, 0, sizeof(struct kthread_worker)); |
fe99a4f4d kthread: Convert ... |
599 |
raw_spin_lock_init(&worker->lock); |
4f32e9b1f kthread_work: mak... |
600 601 |
lockdep_set_class_and_name(&worker->lock, key, name); INIT_LIST_HEAD(&worker->work_list); |
22597dc3d kthread: initial ... |
602 |
INIT_LIST_HEAD(&worker->delayed_work_list); |
4f32e9b1f kthread_work: mak... |
603 |
} |
3989144f8 kthread: kthread ... |
604 |
EXPORT_SYMBOL_GPL(__kthread_init_worker); |
4f32e9b1f kthread_work: mak... |
605 |
|
b56c0d893 kthread: implemen... |
606 607 608 609 |
/** * kthread_worker_fn - kthread function to process kthread_worker * @worker_ptr: pointer to initialized kthread_worker * |
fbae2d44a kthread: add kthr... |
610 611 612 |
* This function implements the main cycle of kthread worker. It processes * work_list until it is stopped with kthread_stop(). It sleeps when the queue * is empty. |
b56c0d893 kthread: implemen... |
613 |
* |
fbae2d44a kthread: add kthr... |
614 615 616 |
* The works are not allowed to keep any locks, disable preemption or interrupts * when they finish. There is defined a safe point for freezing when one work * finishes and before a new one is started. |
8197b3d43 kthread: detect w... |
617 618 619 |
* * Also the works must not be handled by more than one worker at the same time, * see also kthread_queue_work(). |
b56c0d893 kthread: implemen... |
620 621 622 623 624 |
*/ int kthread_worker_fn(void *worker_ptr) { struct kthread_worker *worker = worker_ptr; struct kthread_work *work; |
fbae2d44a kthread: add kthr... |
625 626 627 628 629 |
/* * FIXME: Update the check and remove the assignment when all kthread * worker users are created using kthread_create_worker*() functions. */ WARN_ON(worker->task && worker->task != current); |
b56c0d893 kthread: implemen... |
630 |
worker->task = current; |
dbf52682c kthread: better s... |
631 632 633 |
if (worker->flags & KTW_FREEZABLE) set_freezable(); |
b56c0d893 kthread: implemen... |
634 635 636 637 638 |
repeat: set_current_state(TASK_INTERRUPTIBLE); /* mb paired w/ kthread_stop */ if (kthread_should_stop()) { __set_current_state(TASK_RUNNING); |
fe99a4f4d kthread: Convert ... |
639 |
raw_spin_lock_irq(&worker->lock); |
b56c0d893 kthread: implemen... |
640 |
worker->task = NULL; |
fe99a4f4d kthread: Convert ... |
641 |
raw_spin_unlock_irq(&worker->lock); |
b56c0d893 kthread: implemen... |
642 643 644 645 |
return 0; } work = NULL; |
fe99a4f4d kthread: Convert ... |
646 |
raw_spin_lock_irq(&worker->lock); |
b56c0d893 kthread: implemen... |
647 648 649 650 651 |
if (!list_empty(&worker->work_list)) { work = list_first_entry(&worker->work_list, struct kthread_work, node); list_del_init(&work->node); } |
46f3d9762 kthread_worker: r... |
652 |
worker->current_work = work; |
fe99a4f4d kthread: Convert ... |
653 |
raw_spin_unlock_irq(&worker->lock); |
b56c0d893 kthread: implemen... |
654 655 656 657 |
if (work) { __set_current_state(TASK_RUNNING); work->func(work); |
b56c0d893 kthread: implemen... |
658 659 660 661 |
} else if (!freezing(current)) schedule(); try_to_freeze(); |
22cf8bc6c kernel/kthread.c:... |
662 |
cond_resched(); |
b56c0d893 kthread: implemen... |
663 664 665 |
goto repeat; } EXPORT_SYMBOL_GPL(kthread_worker_fn); |
c0b942a76 kthread: add __pr... |
666 |
static __printf(3, 0) struct kthread_worker * |
dbf52682c kthread: better s... |
667 668 |
__kthread_create_worker(int cpu, unsigned int flags, const char namefmt[], va_list args) |
fbae2d44a kthread: add kthr... |
669 670 671 |
{ struct kthread_worker *worker; struct task_struct *task; |
98fa15f34 mm: replace all o... |
672 |
int node = NUMA_NO_NODE; |
fbae2d44a kthread: add kthr... |
673 674 675 676 677 678 |
worker = kzalloc(sizeof(*worker), GFP_KERNEL); if (!worker) return ERR_PTR(-ENOMEM); kthread_init_worker(worker); |
8fb9dcbdc kthread: Don't ab... |
679 680 |
if (cpu >= 0) node = cpu_to_node(cpu); |
fbae2d44a kthread: add kthr... |
681 |
|
8fb9dcbdc kthread: Don't ab... |
682 683 |
task = __kthread_create_on_node(kthread_worker_fn, worker, node, namefmt, args); |
fbae2d44a kthread: add kthr... |
684 685 |
if (IS_ERR(task)) goto fail_task; |
8fb9dcbdc kthread: Don't ab... |
686 687 |
if (cpu >= 0) kthread_bind(task, cpu); |
dbf52682c kthread: better s... |
688 |
worker->flags = flags; |
fbae2d44a kthread: add kthr... |
689 690 691 692 693 694 695 696 697 698 699 |
worker->task = task; wake_up_process(task); return worker; fail_task: kfree(worker); return ERR_CAST(task); } /** * kthread_create_worker - create a kthread worker |
dbf52682c kthread: better s... |
700 |
* @flags: flags modifying the default behavior of the worker |
fbae2d44a kthread: add kthr... |
701 702 703 704 705 706 707 |
* @namefmt: printf-style name for the kthread worker (task). * * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM) * when the needed structures could not get allocated, and ERR_PTR(-EINTR) * when the worker was SIGKILLed. */ struct kthread_worker * |
dbf52682c kthread: better s... |
708 |
kthread_create_worker(unsigned int flags, const char namefmt[], ...) |
fbae2d44a kthread: add kthr... |
709 710 711 712 713 |
{ struct kthread_worker *worker; va_list args; va_start(args, namefmt); |
dbf52682c kthread: better s... |
714 |
worker = __kthread_create_worker(-1, flags, namefmt, args); |
fbae2d44a kthread: add kthr... |
715 716 717 718 719 720 721 722 723 724 |
va_end(args); return worker; } EXPORT_SYMBOL(kthread_create_worker); /** * kthread_create_worker_on_cpu - create a kthread worker and bind it * it to a given CPU and the associated NUMA node. * @cpu: CPU number |
dbf52682c kthread: better s... |
725 |
* @flags: flags modifying the default behavior of the worker |
fbae2d44a kthread: add kthr... |
726 727 728 729 730 731 732 733 734 735 736 737 738 |
* @namefmt: printf-style name for the kthread worker (task). * * Use a valid CPU number if you want to bind the kthread worker * to the given CPU and the associated NUMA node. * * A good practice is to add the cpu number also into the worker name. * For example, use kthread_create_worker_on_cpu(cpu, "helper/%d", cpu). * * Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM) * when the needed structures could not get allocated, and ERR_PTR(-EINTR) * when the worker was SIGKILLed. */ struct kthread_worker * |
dbf52682c kthread: better s... |
739 740 |
kthread_create_worker_on_cpu(int cpu, unsigned int flags, const char namefmt[], ...) |
fbae2d44a kthread: add kthr... |
741 742 743 744 745 |
{ struct kthread_worker *worker; va_list args; va_start(args, namefmt); |
dbf52682c kthread: better s... |
746 |
worker = __kthread_create_worker(cpu, flags, namefmt, args); |
fbae2d44a kthread: add kthr... |
747 748 749 750 751 |
va_end(args); return worker; } EXPORT_SYMBOL(kthread_create_worker_on_cpu); |
37be45d49 kthread: allow to... |
752 753 754 755 756 757 758 759 760 761 762 763 |
/* * Returns true when the work could not be queued at the moment. * It happens when it is already pending in a worker list * or when it is being cancelled. */ static inline bool queuing_blocked(struct kthread_worker *worker, struct kthread_work *work) { lockdep_assert_held(&worker->lock); return !list_empty(&work->node) || work->canceling; } |
8197b3d43 kthread: detect w... |
764 765 766 767 768 769 770 771 |
static void kthread_insert_work_sanity_check(struct kthread_worker *worker, struct kthread_work *work) { lockdep_assert_held(&worker->lock); WARN_ON_ONCE(!list_empty(&work->node)); /* Do not use a work with >1 worker, see kthread_queue_work() */ WARN_ON_ONCE(work->worker && work->worker != worker); } |
9a2e03d8e kthread_worker: r... |
772 |
/* insert @work before @pos in @worker */ |
3989144f8 kthread: kthread ... |
773 |
static void kthread_insert_work(struct kthread_worker *worker, |
8197b3d43 kthread: detect w... |
774 775 |
struct kthread_work *work, struct list_head *pos) |
9a2e03d8e kthread_worker: r... |
776 |
{ |
8197b3d43 kthread: detect w... |
777 |
kthread_insert_work_sanity_check(worker, work); |
9a2e03d8e kthread_worker: r... |
778 779 |
list_add_tail(&work->node, pos); |
46f3d9762 kthread_worker: r... |
780 |
work->worker = worker; |
ed1403ec2 kthread_work: wak... |
781 |
if (!worker->current_work && likely(worker->task)) |
9a2e03d8e kthread_worker: r... |
782 783 |
wake_up_process(worker->task); } |
b56c0d893 kthread: implemen... |
784 |
/** |
3989144f8 kthread: kthread ... |
785 |
* kthread_queue_work - queue a kthread_work |
b56c0d893 kthread: implemen... |
786 787 788 789 790 791 |
* @worker: target kthread_worker * @work: kthread_work to queue * * Queue @work to work processor @task for async execution. @task * must have been created with kthread_worker_create(). Returns %true * if @work was successfully queued, %false if it was already pending. |
8197b3d43 kthread: detect w... |
792 793 794 |
* * Reinitialize the work if it needs to be used by another worker. * For example, when the worker was stopped and started again. |
b56c0d893 kthread: implemen... |
795 |
*/ |
3989144f8 kthread: kthread ... |
796 |
bool kthread_queue_work(struct kthread_worker *worker, |
b56c0d893 kthread: implemen... |
797 798 799 800 |
struct kthread_work *work) { bool ret = false; unsigned long flags; |
fe99a4f4d kthread: Convert ... |
801 |
raw_spin_lock_irqsave(&worker->lock, flags); |
37be45d49 kthread: allow to... |
802 |
if (!queuing_blocked(worker, work)) { |
3989144f8 kthread: kthread ... |
803 |
kthread_insert_work(worker, work, &worker->work_list); |
b56c0d893 kthread: implemen... |
804 805 |
ret = true; } |
fe99a4f4d kthread: Convert ... |
806 |
raw_spin_unlock_irqrestore(&worker->lock, flags); |
b56c0d893 kthread: implemen... |
807 808 |
return ret; } |
3989144f8 kthread: kthread ... |
809 |
EXPORT_SYMBOL_GPL(kthread_queue_work); |
b56c0d893 kthread: implemen... |
810 |
|
22597dc3d kthread: initial ... |
811 812 813 |
/** * kthread_delayed_work_timer_fn - callback that queues the associated kthread * delayed work when the timer expires. |
fe5c3b69b kthread: Convert ... |
814 |
* @t: pointer to the expired timer |
22597dc3d kthread: initial ... |
815 816 817 818 |
* * The format of the function is defined by struct timer_list. * It should have been called from irqsafe timer with irq already off. */ |
fe5c3b69b kthread: Convert ... |
819 |
void kthread_delayed_work_timer_fn(struct timer_list *t) |
22597dc3d kthread: initial ... |
820 |
{ |
fe5c3b69b kthread: Convert ... |
821 |
struct kthread_delayed_work *dwork = from_timer(dwork, t, timer); |
22597dc3d kthread: initial ... |
822 823 |
struct kthread_work *work = &dwork->work; struct kthread_worker *worker = work->worker; |
ad01423ae kthread: Do not u... |
824 |
unsigned long flags; |
22597dc3d kthread: initial ... |
825 826 827 828 829 830 831 |
/* * This might happen when a pending work is reinitialized. * It means that it is used a wrong way. */ if (WARN_ON_ONCE(!worker)) return; |
ad01423ae kthread: Do not u... |
832 |
raw_spin_lock_irqsave(&worker->lock, flags); |
22597dc3d kthread: initial ... |
833 834 835 836 837 838 839 |
/* Work must not be used with >1 worker, see kthread_queue_work(). */ WARN_ON_ONCE(work->worker != worker); /* Move the work from worker->delayed_work_list. */ WARN_ON_ONCE(list_empty(&work->node)); list_del_init(&work->node); kthread_insert_work(worker, work, &worker->work_list); |
ad01423ae kthread: Do not u... |
840 |
raw_spin_unlock_irqrestore(&worker->lock, flags); |
22597dc3d kthread: initial ... |
841 842 |
} EXPORT_SYMBOL(kthread_delayed_work_timer_fn); |
bc88f85c6 kthread: make __k... |
843 844 845 |
static void __kthread_queue_delayed_work(struct kthread_worker *worker, struct kthread_delayed_work *dwork, unsigned long delay) |
22597dc3d kthread: initial ... |
846 847 848 |
{ struct timer_list *timer = &dwork->timer; struct kthread_work *work = &dwork->work; |
841b86f32 treewide: Remove ... |
849 |
WARN_ON_ONCE(timer->function != kthread_delayed_work_timer_fn); |
22597dc3d kthread: initial ... |
850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 |
/* * If @delay is 0, queue @dwork->work immediately. This is for * both optimization and correctness. The earliest @timer can * expire is on the closest next tick and delayed_work users depend * on that there's no such delay when @delay is 0. */ if (!delay) { kthread_insert_work(worker, work, &worker->work_list); return; } /* Be paranoid and try to detect possible races already now. */ kthread_insert_work_sanity_check(worker, work); list_add(&work->node, &worker->delayed_work_list); work->worker = worker; |
22597dc3d kthread: initial ... |
867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 |
timer->expires = jiffies + delay; add_timer(timer); } /** * kthread_queue_delayed_work - queue the associated kthread work * after a delay. * @worker: target kthread_worker * @dwork: kthread_delayed_work to queue * @delay: number of jiffies to wait before queuing * * If the work has not been pending it starts a timer that will queue * the work after the given @delay. If @delay is zero, it queues the * work immediately. * * Return: %false if the @work has already been pending. It means that * either the timer was running or the work was queued. It returns %true * otherwise. */ bool kthread_queue_delayed_work(struct kthread_worker *worker, struct kthread_delayed_work *dwork, unsigned long delay) { struct kthread_work *work = &dwork->work; unsigned long flags; bool ret = false; |
fe99a4f4d kthread: Convert ... |
893 |
raw_spin_lock_irqsave(&worker->lock, flags); |
22597dc3d kthread: initial ... |
894 |
|
37be45d49 kthread: allow to... |
895 |
if (!queuing_blocked(worker, work)) { |
22597dc3d kthread: initial ... |
896 897 898 |
__kthread_queue_delayed_work(worker, dwork, delay); ret = true; } |
fe99a4f4d kthread: Convert ... |
899 |
raw_spin_unlock_irqrestore(&worker->lock, flags); |
22597dc3d kthread: initial ... |
900 901 902 |
return ret; } EXPORT_SYMBOL_GPL(kthread_queue_delayed_work); |
9a2e03d8e kthread_worker: r... |
903 904 905 906 907 908 909 910 911 912 913 |
struct kthread_flush_work { struct kthread_work work; struct completion done; }; static void kthread_flush_work_fn(struct kthread_work *work) { struct kthread_flush_work *fwork = container_of(work, struct kthread_flush_work, work); complete(&fwork->done); } |
b56c0d893 kthread: implemen... |
914 |
/** |
3989144f8 kthread: kthread ... |
915 |
* kthread_flush_work - flush a kthread_work |
b56c0d893 kthread: implemen... |
916 917 918 919 |
* @work: work to flush * * If @work is queued or executing, wait for it to finish execution. */ |
3989144f8 kthread: kthread ... |
920 |
void kthread_flush_work(struct kthread_work *work) |
b56c0d893 kthread: implemen... |
921 |
{ |
46f3d9762 kthread_worker: r... |
922 923 924 925 926 927 |
struct kthread_flush_work fwork = { KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), COMPLETION_INITIALIZER_ONSTACK(fwork.done), }; struct kthread_worker *worker; bool noop = false; |
46f3d9762 kthread_worker: r... |
928 929 930 |
worker = work->worker; if (!worker) return; |
b56c0d893 kthread: implemen... |
931 |
|
fe99a4f4d kthread: Convert ... |
932 |
raw_spin_lock_irq(&worker->lock); |
8197b3d43 kthread: detect w... |
933 934 |
/* Work must not be used with >1 worker, see kthread_queue_work(). */ WARN_ON_ONCE(work->worker != worker); |
b56c0d893 kthread: implemen... |
935 |
|
46f3d9762 kthread_worker: r... |
936 |
if (!list_empty(&work->node)) |
3989144f8 kthread: kthread ... |
937 |
kthread_insert_work(worker, &fwork.work, work->node.next); |
46f3d9762 kthread_worker: r... |
938 |
else if (worker->current_work == work) |
3989144f8 kthread: kthread ... |
939 940 |
kthread_insert_work(worker, &fwork.work, worker->work_list.next); |
46f3d9762 kthread_worker: r... |
941 942 |
else noop = true; |
b56c0d893 kthread: implemen... |
943 |
|
fe99a4f4d kthread: Convert ... |
944 |
raw_spin_unlock_irq(&worker->lock); |
b56c0d893 kthread: implemen... |
945 |
|
46f3d9762 kthread_worker: r... |
946 947 |
if (!noop) wait_for_completion(&fwork.done); |
b56c0d893 kthread: implemen... |
948 |
} |
3989144f8 kthread: kthread ... |
949 |
EXPORT_SYMBOL_GPL(kthread_flush_work); |
b56c0d893 kthread: implemen... |
950 |
|
37be45d49 kthread: allow to... |
951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 |
/* * This function removes the work from the worker queue. Also it makes sure * that it won't get queued later via the delayed work's timer. * * The work might still be in use when this function finishes. See the * current_work proceed by the worker. * * Return: %true if @work was pending and successfully canceled, * %false if @work was not pending */ static bool __kthread_cancel_work(struct kthread_work *work, bool is_dwork, unsigned long *flags) { /* Try to cancel the timer if exists. */ if (is_dwork) { struct kthread_delayed_work *dwork = container_of(work, struct kthread_delayed_work, work); struct kthread_worker *worker = work->worker; /* * del_timer_sync() must be called to make sure that the timer * callback is not running. The lock must be temporary released * to avoid a deadlock with the callback. In the meantime, * any queuing is blocked by setting the canceling counter. */ work->canceling++; |
fe99a4f4d kthread: Convert ... |
977 |
raw_spin_unlock_irqrestore(&worker->lock, *flags); |
37be45d49 kthread: allow to... |
978 |
del_timer_sync(&dwork->timer); |
fe99a4f4d kthread: Convert ... |
979 |
raw_spin_lock_irqsave(&worker->lock, *flags); |
37be45d49 kthread: allow to... |
980 981 982 983 984 985 986 987 988 989 990 991 992 993 |
work->canceling--; } /* * Try to remove the work from a worker list. It might either * be from worker->work_list or from worker->delayed_work_list. */ if (!list_empty(&work->node)) { list_del_init(&work->node); return true; } return false; } |
9a6b06c8d kthread: allow to... |
994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 |
/** * kthread_mod_delayed_work - modify delay of or queue a kthread delayed work * @worker: kthread worker to use * @dwork: kthread delayed work to queue * @delay: number of jiffies to wait before queuing * * If @dwork is idle, equivalent to kthread_queue_delayed_work(). Otherwise, * modify @dwork's timer so that it expires after @delay. If @delay is zero, * @work is guaranteed to be queued immediately. * * Return: %true if @dwork was pending and its timer was modified, * %false otherwise. * * A special case is when the work is being canceled in parallel. * It might be caused either by the real kthread_cancel_delayed_work_sync() * or yet another kthread_mod_delayed_work() call. We let the other command * win and return %false here. The caller is supposed to synchronize these * operations a reasonable way. * * This function is safe to call from any context including IRQ handler. * See __kthread_cancel_work() and kthread_delayed_work_timer_fn() * for details. */ bool kthread_mod_delayed_work(struct kthread_worker *worker, struct kthread_delayed_work *dwork, unsigned long delay) { struct kthread_work *work = &dwork->work; unsigned long flags; int ret = false; |
fe99a4f4d kthread: Convert ... |
1024 |
raw_spin_lock_irqsave(&worker->lock, flags); |
9a6b06c8d kthread: allow to... |
1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 |
/* Do not bother with canceling when never queued. */ if (!work->worker) goto fast_queue; /* Work must not be used with >1 worker, see kthread_queue_work() */ WARN_ON_ONCE(work->worker != worker); /* Do not fight with another command that is canceling this work. */ if (work->canceling) goto out; ret = __kthread_cancel_work(work, true, &flags); fast_queue: __kthread_queue_delayed_work(worker, dwork, delay); out: |
fe99a4f4d kthread: Convert ... |
1041 |
raw_spin_unlock_irqrestore(&worker->lock, flags); |
9a6b06c8d kthread: allow to... |
1042 1043 1044 |
return ret; } EXPORT_SYMBOL_GPL(kthread_mod_delayed_work); |
37be45d49 kthread: allow to... |
1045 1046 1047 1048 1049 1050 1051 1052 |
static bool __kthread_cancel_work_sync(struct kthread_work *work, bool is_dwork) { struct kthread_worker *worker = work->worker; unsigned long flags; int ret = false; if (!worker) goto out; |
fe99a4f4d kthread: Convert ... |
1053 |
raw_spin_lock_irqsave(&worker->lock, flags); |
37be45d49 kthread: allow to... |
1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 |
/* Work must not be used with >1 worker, see kthread_queue_work(). */ WARN_ON_ONCE(work->worker != worker); ret = __kthread_cancel_work(work, is_dwork, &flags); if (worker->current_work != work) goto out_fast; /* * The work is in progress and we need to wait with the lock released. * In the meantime, block any queuing by setting the canceling counter. */ work->canceling++; |
fe99a4f4d kthread: Convert ... |
1067 |
raw_spin_unlock_irqrestore(&worker->lock, flags); |
37be45d49 kthread: allow to... |
1068 |
kthread_flush_work(work); |
fe99a4f4d kthread: Convert ... |
1069 |
raw_spin_lock_irqsave(&worker->lock, flags); |
37be45d49 kthread: allow to... |
1070 1071 1072 |
work->canceling--; out_fast: |
fe99a4f4d kthread: Convert ... |
1073 |
raw_spin_unlock_irqrestore(&worker->lock, flags); |
37be45d49 kthread: allow to... |
1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 |
out: return ret; } /** * kthread_cancel_work_sync - cancel a kthread work and wait for it to finish * @work: the kthread work to cancel * * Cancel @work and wait for its execution to finish. This function * can be used even if the work re-queues itself. On return from this * function, @work is guaranteed to be not pending or executing on any CPU. * * kthread_cancel_work_sync(&delayed_work->work) must not be used for * delayed_work's. Use kthread_cancel_delayed_work_sync() instead. * * The caller must ensure that the worker on which @work was last * queued can't be destroyed before this function returns. * * Return: %true if @work was pending, %false otherwise. */ bool kthread_cancel_work_sync(struct kthread_work *work) { return __kthread_cancel_work_sync(work, false); } EXPORT_SYMBOL_GPL(kthread_cancel_work_sync); /** * kthread_cancel_delayed_work_sync - cancel a kthread delayed work and * wait for it to finish. * @dwork: the kthread delayed work to cancel * * This is kthread_cancel_work_sync() for delayed works. * * Return: %true if @dwork was pending, %false otherwise. */ bool kthread_cancel_delayed_work_sync(struct kthread_delayed_work *dwork) { return __kthread_cancel_work_sync(&dwork->work, true); } EXPORT_SYMBOL_GPL(kthread_cancel_delayed_work_sync); |
b56c0d893 kthread: implemen... |
1114 |
/** |
3989144f8 kthread: kthread ... |
1115 |
* kthread_flush_worker - flush all current works on a kthread_worker |
b56c0d893 kthread: implemen... |
1116 1117 1118 1119 1120 |
* @worker: worker to flush * * Wait until all currently executing or pending works on @worker are * finished. */ |
3989144f8 kthread: kthread ... |
1121 |
void kthread_flush_worker(struct kthread_worker *worker) |
b56c0d893 kthread: implemen... |
1122 1123 1124 1125 1126 |
{ struct kthread_flush_work fwork = { KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn), COMPLETION_INITIALIZER_ONSTACK(fwork.done), }; |
3989144f8 kthread: kthread ... |
1127 |
kthread_queue_work(worker, &fwork.work); |
b56c0d893 kthread: implemen... |
1128 1129 |
wait_for_completion(&fwork.done); } |
3989144f8 kthread: kthread ... |
1130 |
EXPORT_SYMBOL_GPL(kthread_flush_worker); |
35033fe9c kthread: add kthr... |
1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 |
/** * kthread_destroy_worker - destroy a kthread worker * @worker: worker to be destroyed * * Flush and destroy @worker. The simple flush is enough because the kthread * worker API is used only in trivial scenarios. There are no multi-step state * machines needed. */ void kthread_destroy_worker(struct kthread_worker *worker) { struct task_struct *task; task = worker->task; if (WARN_ON(!task)) return; kthread_flush_worker(worker); kthread_stop(task); WARN_ON(!list_empty(&worker->work_list)); kfree(worker); } EXPORT_SYMBOL(kthread_destroy_worker); |
05e3db95e kthread: add a me... |
1154 |
|
0b508bc92 block: fix a buil... |
1155 |
#ifdef CONFIG_BLK_CGROUP |
05e3db95e kthread: add a me... |
1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 |
/** * kthread_associate_blkcg - associate blkcg to current kthread * @css: the cgroup info * * Current thread must be a kthread. The thread is running jobs on behalf of * other threads. In some cases, we expect the jobs attach cgroup info of * original threads instead of that of current thread. This function stores * original thread's cgroup info in current kthread context for later * retrieval. */ void kthread_associate_blkcg(struct cgroup_subsys_state *css) { struct kthread *kthread; if (!(current->flags & PF_KTHREAD)) return; kthread = to_kthread(current); if (!kthread) return; if (kthread->blkcg_css) { css_put(kthread->blkcg_css); kthread->blkcg_css = NULL; } if (css) { css_get(css); kthread->blkcg_css = css; } } EXPORT_SYMBOL(kthread_associate_blkcg); /** * kthread_blkcg - get associated blkcg css of current kthread * * Current thread must be a kthread. */ struct cgroup_subsys_state *kthread_blkcg(void) { struct kthread *kthread; if (current->flags & PF_KTHREAD) { kthread = to_kthread(current); if (kthread) return kthread->blkcg_css; } return NULL; } EXPORT_SYMBOL(kthread_blkcg); #endif |