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ipc/sem.c
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/* * linux/ipc/sem.c * Copyright (C) 1992 Krishna Balasubramanian * Copyright (C) 1995 Eric Schenk, Bruno Haible * * IMPLEMENTATION NOTES ON CODE REWRITE (Eric Schenk, January 1995): * This code underwent a massive rewrite in order to solve some problems * with the original code. In particular the original code failed to * wake up processes that were waiting for semval to go to 0 if the * value went to 0 and was then incremented rapidly enough. In solving * this problem I have also modified the implementation so that it * processes pending operations in a FIFO manner, thus give a guarantee * that processes waiting for a lock on the semaphore won't starve * unless another locking process fails to unlock. * In addition the following two changes in behavior have been introduced: * - The original implementation of semop returned the value * last semaphore element examined on success. This does not * match the manual page specifications, and effectively * allows the user to read the semaphore even if they do not * have read permissions. The implementation now returns 0 * on success as stated in the manual page. * - There is some confusion over whether the set of undo adjustments * to be performed at exit should be done in an atomic manner. * That is, if we are attempting to decrement the semval should we queue * up and wait until we can do so legally? * The original implementation attempted to do this. * The current implementation does not do so. This is because I don't * think it is the right thing (TM) to do, and because I couldn't * see a clean way to get the old behavior with the new design. * The POSIX standard and SVID should be consulted to determine * what behavior is mandated. * * Further notes on refinement (Christoph Rohland, December 1998): * - The POSIX standard says, that the undo adjustments simply should * redo. So the current implementation is o.K. * - The previous code had two flaws: * 1) It actively gave the semaphore to the next waiting process * sleeping on the semaphore. Since this process did not have the * cpu this led to many unnecessary context switches and bad * performance. Now we only check which process should be able to * get the semaphore and if this process wants to reduce some * semaphore value we simply wake it up without doing the * operation. So it has to try to get it later. Thus e.g. the * running process may reacquire the semaphore during the current * time slice. If it only waits for zero or increases the semaphore, * we do the operation in advance and wake it up. * 2) It did not wake up all zero waiting processes. We try to do * better but only get the semops right which only wait for zero or * increase. If there are decrement operations in the operations * array we do the same as before. * * With the incarnation of O(1) scheduler, it becomes unnecessary to perform * check/retry algorithm for waking up blocked processes as the new scheduler * is better at handling thread switch than the old one. * * /proc/sysvipc/sem support (c) 1999 Dragos Acostachioaie <dragos@iname.com> * * SMP-threaded, sysctl's added |
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* (c) 1999 Manfred Spraul <manfred@colorfullife.com> |
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* Enforced range limit on SEM_UNDO * (c) 2001 Red Hat Inc <alan@redhat.com> * Lockless wakeup * (c) 2003 Manfred Spraul <manfred@colorfullife.com> |
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* * support for audit of ipc object properties and permission changes * Dustin Kirkland <dustin.kirkland@us.ibm.com> |
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* * namespaces support * OpenVZ, SWsoft Inc. * Pavel Emelianov <xemul@openvz.org> |
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*/ |
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#include <linux/slab.h> #include <linux/spinlock.h> #include <linux/init.h> #include <linux/proc_fs.h> #include <linux/time.h> |
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#include <linux/security.h> #include <linux/syscalls.h> #include <linux/audit.h> |
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#include <linux/capability.h> |
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#include <linux/seq_file.h> |
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#include <linux/rwsem.h> |
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#include <linux/nsproxy.h> |
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#include <linux/ipc_namespace.h> |
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|
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#include <asm/uaccess.h> #include "util.h" |
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#define sem_ids(ns) ((ns)->ids[IPC_SEM_IDS]) |
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|
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#define sem_unlock(sma) ipc_unlock(&(sma)->sem_perm) |
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#define sem_checkid(sma, semid) ipc_checkid(&sma->sem_perm, semid) |
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|
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static int newary(struct ipc_namespace *, struct ipc_params *); |
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static void freeary(struct ipc_namespace *, struct kern_ipc_perm *); |
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#ifdef CONFIG_PROC_FS |
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static int sysvipc_sem_proc_show(struct seq_file *s, void *it); |
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#endif #define SEMMSL_FAST 256 /* 512 bytes on stack */ #define SEMOPM_FAST 64 /* ~ 372 bytes on stack */ /* * linked list protection: * sem_undo.id_next, * sem_array.sem_pending{,last}, * sem_array.sem_undo: sem_lock() for read/write * sem_undo.proc_next: only "current" is allowed to read/write that field. * */ |
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#define sc_semmsl sem_ctls[0] #define sc_semmns sem_ctls[1] #define sc_semopm sem_ctls[2] #define sc_semmni sem_ctls[3] |
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void sem_init_ns(struct ipc_namespace *ns) |
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{ |
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ns->sc_semmsl = SEMMSL; ns->sc_semmns = SEMMNS; ns->sc_semopm = SEMOPM; ns->sc_semmni = SEMMNI; ns->used_sems = 0; |
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ipc_init_ids(&ns->ids[IPC_SEM_IDS]); |
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} |
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#ifdef CONFIG_IPC_NS |
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void sem_exit_ns(struct ipc_namespace *ns) { |
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free_ipcs(ns, &sem_ids(ns), freeary); |
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} |
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#endif |
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void __init sem_init (void) { |
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sem_init_ns(&init_ipc_ns); |
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ipc_init_proc_interface("sysvipc/sem", " key semid perms nsems uid gid cuid cgid otime ctime ", |
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IPC_SEM_IDS, sysvipc_sem_proc_show); |
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} |
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/* |
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* sem_lock_(check_) routines are called in the paths where the rw_mutex * is not held. */ |
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static inline struct sem_array *sem_lock(struct ipc_namespace *ns, int id) { |
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struct kern_ipc_perm *ipcp = ipc_lock(&sem_ids(ns), id); |
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if (IS_ERR(ipcp)) return (struct sem_array *)ipcp; |
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return container_of(ipcp, struct sem_array, sem_perm); |
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} static inline struct sem_array *sem_lock_check(struct ipc_namespace *ns, int id) { |
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struct kern_ipc_perm *ipcp = ipc_lock_check(&sem_ids(ns), id); |
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if (IS_ERR(ipcp)) return (struct sem_array *)ipcp; |
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return container_of(ipcp, struct sem_array, sem_perm); |
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} |
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static inline void sem_lock_and_putref(struct sem_array *sma) { ipc_lock_by_ptr(&sma->sem_perm); ipc_rcu_putref(sma); } static inline void sem_getref_and_unlock(struct sem_array *sma) { ipc_rcu_getref(sma); ipc_unlock(&(sma)->sem_perm); } static inline void sem_putref(struct sem_array *sma) { ipc_lock_by_ptr(&sma->sem_perm); ipc_rcu_putref(sma); ipc_unlock(&(sma)->sem_perm); } |
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static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s) { ipc_rmid(&sem_ids(ns), &s->sem_perm); } |
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/* * Lockless wakeup algorithm: * Without the check/retry algorithm a lockless wakeup is possible: * - queue.status is initialized to -EINTR before blocking. * - wakeup is performed by * * unlinking the queue entry from sma->sem_pending * * setting queue.status to IN_WAKEUP * This is the notification for the blocked thread that a * result value is imminent. * * call wake_up_process * * set queue.status to the final value. * - the previously blocked thread checks queue.status: * * if it's IN_WAKEUP, then it must wait until the value changes * * if it's not -EINTR, then the operation was completed by * update_queue. semtimedop can return queue.status without |
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* performing any operation on the sem array. |
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* * otherwise it must acquire the spinlock and check what's up. * * The two-stage algorithm is necessary to protect against the following * races: * - if queue.status is set after wake_up_process, then the woken up idle * thread could race forward and try (and fail) to acquire sma->lock * before update_queue had a chance to set queue.status * - if queue.status is written before wake_up_process and if the * blocked process is woken up by a signal between writing * queue.status and the wake_up_process, then the woken up * process could return from semtimedop and die by calling * sys_exit before wake_up_process is called. Then wake_up_process * will oops, because the task structure is already invalid. * (yes, this happened on s390 with sysv msg). * */ #define IN_WAKEUP 1 |
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/** * newary - Create a new semaphore set * @ns: namespace * @params: ptr to the structure that contains key, semflg and nsems * |
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* Called with sem_ids.rw_mutex held (as a writer) |
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*/ |
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static int newary(struct ipc_namespace *ns, struct ipc_params *params) |
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{ int id; int retval; struct sem_array *sma; int size; |
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key_t key = params->key; int nsems = params->u.nsems; int semflg = params->flg; |
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if (!nsems) return -EINVAL; |
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if (ns->used_sems + nsems > ns->sc_semmns) |
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return -ENOSPC; size = sizeof (*sma) + nsems * sizeof (struct sem); sma = ipc_rcu_alloc(size); if (!sma) { return -ENOMEM; } memset (sma, 0, size); sma->sem_perm.mode = (semflg & S_IRWXUGO); sma->sem_perm.key = key; sma->sem_perm.security = NULL; retval = security_sem_alloc(sma); if (retval) { ipc_rcu_putref(sma); return retval; } |
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id = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni); |
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if (id < 0) { |
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security_sem_free(sma); ipc_rcu_putref(sma); |
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return id; |
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} |
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ns->used_sems += nsems; |
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sma->sem_base = (struct sem *) &sma[1]; |
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INIT_LIST_HEAD(&sma->sem_pending); |
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INIT_LIST_HEAD(&sma->list_id); |
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sma->sem_nsems = nsems; sma->sem_ctime = get_seconds(); sem_unlock(sma); |
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return sma->sem_perm.id; |
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} |
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|
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/* |
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* Called with sem_ids.rw_mutex and ipcp locked. |
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*/ |
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static inline int sem_security(struct kern_ipc_perm *ipcp, int semflg) |
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{ |
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struct sem_array *sma; sma = container_of(ipcp, struct sem_array, sem_perm); return security_sem_associate(sma, semflg); |
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} |
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/* |
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* Called with sem_ids.rw_mutex and ipcp locked. |
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*/ |
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static inline int sem_more_checks(struct kern_ipc_perm *ipcp, struct ipc_params *params) |
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{ |
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struct sem_array *sma; sma = container_of(ipcp, struct sem_array, sem_perm); if (params->u.nsems > sma->sem_nsems) |
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return -EINVAL; return 0; } asmlinkage long sys_semget(key_t key, int nsems, int semflg) |
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{ |
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struct ipc_namespace *ns; |
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struct ipc_ops sem_ops; struct ipc_params sem_params; |
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ns = current->nsproxy->ipc_ns; |
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|
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if (nsems < 0 || nsems > ns->sc_semmsl) |
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return -EINVAL; |
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|
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sem_ops.getnew = newary; sem_ops.associate = sem_security; sem_ops.more_checks = sem_more_checks; sem_params.key = key; sem_params.flg = semflg; sem_params.u.nsems = nsems; |
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|
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return ipcget(ns, &sem_ids(ns), &sem_ops, &sem_params); |
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} |
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/* * Determine whether a sequence of semaphore operations would succeed * all at once. Return 0 if yes, 1 if need to sleep, else return error code. */ static int try_atomic_semop (struct sem_array * sma, struct sembuf * sops, int nsops, struct sem_undo *un, int pid) { int result, sem_op; struct sembuf *sop; struct sem * curr; for (sop = sops; sop < sops + nsops; sop++) { curr = sma->sem_base + sop->sem_num; sem_op = sop->sem_op; result = curr->semval; if (!sem_op && result) goto would_block; result += sem_op; if (result < 0) goto would_block; if (result > SEMVMX) goto out_of_range; if (sop->sem_flg & SEM_UNDO) { int undo = un->semadj[sop->sem_num] - sem_op; /* * Exceeding the undo range is an error. */ if (undo < (-SEMAEM - 1) || undo > SEMAEM) goto out_of_range; } curr->semval = result; } sop--; while (sop >= sops) { sma->sem_base[sop->sem_num].sempid = pid; if (sop->sem_flg & SEM_UNDO) un->semadj[sop->sem_num] -= sop->sem_op; sop--; } sma->sem_otime = get_seconds(); return 0; out_of_range: result = -ERANGE; goto undo; would_block: if (sop->sem_flg & IPC_NOWAIT) result = -EAGAIN; else result = 1; undo: sop--; while (sop >= sops) { sma->sem_base[sop->sem_num].semval -= sop->sem_op; sop--; } return result; } /* Go through the pending queue for the indicated semaphore * looking for tasks that can be completed. */ static void update_queue (struct sem_array * sma) { int error; struct sem_queue * q; |
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q = list_entry(sma->sem_pending.next, struct sem_queue, list); while (&q->list != &sma->sem_pending) { |
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error = try_atomic_semop(sma, q->sops, q->nsops, q->undo, q->pid); /* Does q->sleeper still need to sleep? */ if (error <= 0) { struct sem_queue *n; |
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/* * Continue scanning. The next operation * that must be checked depends on the type of the * completed operation: * - if the operation modified the array, then * restart from the head of the queue and * check for threads that might be waiting * for semaphore values to become 0. * - if the operation didn't modify the array, * then just continue. |
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* The order of list_del() and reading ->next * is crucial: In the former case, the list_del() * must be done first [because we might be the * first entry in ->sem_pending], in the latter * case the list_del() must be done last * [because the list is invalid after the list_del()] |
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*/ |
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if (q->alter) { list_del(&q->list); n = list_entry(sma->sem_pending.next, struct sem_queue, list); } else { n = list_entry(q->list.next, struct sem_queue, list); list_del(&q->list); } /* wake up the waiting thread */ q->status = IN_WAKEUP; |
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wake_up_process(q->sleeper); /* hands-off: q will disappear immediately after * writing q->status. */ |
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smp_wmb(); |
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q->status = error; q = n; } else { |
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q = list_entry(q->list.next, struct sem_queue, list); |
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} } } /* The following counts are associated to each semaphore: * semncnt number of tasks waiting on semval being nonzero * semzcnt number of tasks waiting on semval being zero * This model assumes that a task waits on exactly one semaphore. * Since semaphore operations are to be performed atomically, tasks actually * wait on a whole sequence of semaphores simultaneously. * The counts we return here are a rough approximation, but still * warrant that semncnt+semzcnt>0 if the task is on the pending queue. */ static int count_semncnt (struct sem_array * sma, ushort semnum) { int semncnt; struct sem_queue * q; semncnt = 0; |
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list_for_each_entry(q, &sma->sem_pending, list) { |
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struct sembuf * sops = q->sops; int nsops = q->nsops; int i; for (i = 0; i < nsops; i++) if (sops[i].sem_num == semnum && (sops[i].sem_op < 0) && !(sops[i].sem_flg & IPC_NOWAIT)) semncnt++; } return semncnt; } |
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static int count_semzcnt (struct sem_array * sma, ushort semnum) { int semzcnt; struct sem_queue * q; semzcnt = 0; |
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list_for_each_entry(q, &sma->sem_pending, list) { |
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struct sembuf * sops = q->sops; int nsops = q->nsops; int i; for (i = 0; i < nsops; i++) if (sops[i].sem_num == semnum && (sops[i].sem_op == 0) && !(sops[i].sem_flg & IPC_NOWAIT)) semzcnt++; } return semzcnt; } |
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void free_un(struct rcu_head *head) { struct sem_undo *un = container_of(head, struct sem_undo, rcu); kfree(un); } |
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/* Free a semaphore set. freeary() is called with sem_ids.rw_mutex locked * as a writer and the spinlock for this semaphore set hold. sem_ids.rw_mutex * remains locked on exit. |
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*/ |
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static void freeary(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp) |
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{ |
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struct sem_undo *un, *tu; struct sem_queue *q, *tq; |
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struct sem_array *sma = container_of(ipcp, struct sem_array, sem_perm); |
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/* Free the existing undo structures for this semaphore set. */ |
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501 |
assert_spin_locked(&sma->sem_perm.lock); |
380af1b33 ipc/sem.c: rewrit... |
502 503 504 |
list_for_each_entry_safe(un, tu, &sma->list_id, list_id) { list_del(&un->list_id); spin_lock(&un->ulp->lock); |
1da177e4c Linux-2.6.12-rc2 |
505 |
un->semid = -1; |
380af1b33 ipc/sem.c: rewrit... |
506 507 508 509 |
list_del_rcu(&un->list_proc); spin_unlock(&un->ulp->lock); call_rcu(&un->rcu, free_un); } |
1da177e4c Linux-2.6.12-rc2 |
510 511 |
/* Wake up all pending processes and let them fail with EIDRM. */ |
380af1b33 ipc/sem.c: rewrit... |
512 |
list_for_each_entry_safe(q, tq, &sma->sem_pending, list) { |
a1193f8ec ipc/sem.c: conver... |
513 |
list_del(&q->list); |
1da177e4c Linux-2.6.12-rc2 |
514 515 |
q->status = IN_WAKEUP; wake_up_process(q->sleeper); /* doesn't sleep */ |
6003a93e7 [PATCH] add missi... |
516 |
smp_wmb(); |
1da177e4c Linux-2.6.12-rc2 |
517 |
q->status = -EIDRM; /* hands-off q */ |
1da177e4c Linux-2.6.12-rc2 |
518 |
} |
7ca7e564e ipc: store ipcs i... |
519 520 |
/* Remove the semaphore set from the IDR */ sem_rmid(ns, sma); |
1da177e4c Linux-2.6.12-rc2 |
521 |
sem_unlock(sma); |
e38935341 [PATCH] IPC names... |
522 |
ns->used_sems -= sma->sem_nsems; |
1da177e4c Linux-2.6.12-rc2 |
523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 |
security_sem_free(sma); ipc_rcu_putref(sma); } static unsigned long copy_semid_to_user(void __user *buf, struct semid64_ds *in, int version) { switch(version) { case IPC_64: return copy_to_user(buf, in, sizeof(*in)); case IPC_OLD: { struct semid_ds out; ipc64_perm_to_ipc_perm(&in->sem_perm, &out.sem_perm); out.sem_otime = in->sem_otime; out.sem_ctime = in->sem_ctime; out.sem_nsems = in->sem_nsems; return copy_to_user(buf, &out, sizeof(out)); } default: return -EINVAL; } } |
4b9fcb0ec IPC/semaphores: c... |
548 549 |
static int semctl_nolock(struct ipc_namespace *ns, int semid, int cmd, int version, union semun arg) |
1da177e4c Linux-2.6.12-rc2 |
550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 |
{ int err = -EINVAL; struct sem_array *sma; switch(cmd) { case IPC_INFO: case SEM_INFO: { struct seminfo seminfo; int max_id; err = security_sem_semctl(NULL, cmd); if (err) return err; memset(&seminfo,0,sizeof(seminfo)); |
e38935341 [PATCH] IPC names... |
566 567 568 569 |
seminfo.semmni = ns->sc_semmni; seminfo.semmns = ns->sc_semmns; seminfo.semmsl = ns->sc_semmsl; seminfo.semopm = ns->sc_semopm; |
1da177e4c Linux-2.6.12-rc2 |
570 571 572 573 |
seminfo.semvmx = SEMVMX; seminfo.semmnu = SEMMNU; seminfo.semmap = SEMMAP; seminfo.semume = SEMUME; |
3e148c799 fix idr_find() lo... |
574 |
down_read(&sem_ids(ns).rw_mutex); |
1da177e4c Linux-2.6.12-rc2 |
575 |
if (cmd == SEM_INFO) { |
e38935341 [PATCH] IPC names... |
576 577 |
seminfo.semusz = sem_ids(ns).in_use; seminfo.semaem = ns->used_sems; |
1da177e4c Linux-2.6.12-rc2 |
578 579 580 581 |
} else { seminfo.semusz = SEMUSZ; seminfo.semaem = SEMAEM; } |
7ca7e564e ipc: store ipcs i... |
582 |
max_id = ipc_get_maxid(&sem_ids(ns)); |
3e148c799 fix idr_find() lo... |
583 |
up_read(&sem_ids(ns).rw_mutex); |
1da177e4c Linux-2.6.12-rc2 |
584 585 586 587 |
if (copy_to_user (arg.__buf, &seminfo, sizeof(struct seminfo))) return -EFAULT; return (max_id < 0) ? 0: max_id; } |
4b9fcb0ec IPC/semaphores: c... |
588 |
case IPC_STAT: |
1da177e4c Linux-2.6.12-rc2 |
589 590 591 592 |
case SEM_STAT: { struct semid64_ds tbuf; int id; |
4b9fcb0ec IPC/semaphores: c... |
593 594 595 596 597 598 599 600 601 602 603 |
if (cmd == SEM_STAT) { sma = sem_lock(ns, semid); if (IS_ERR(sma)) return PTR_ERR(sma); id = sma->sem_perm.id; } else { sma = sem_lock_check(ns, semid); if (IS_ERR(sma)) return PTR_ERR(sma); id = 0; } |
1da177e4c Linux-2.6.12-rc2 |
604 605 606 607 608 609 610 611 |
err = -EACCES; if (ipcperms (&sma->sem_perm, S_IRUGO)) goto out_unlock; err = security_sem_semctl(sma, cmd); if (err) goto out_unlock; |
023a53557 ipc: integrate ip... |
612 |
memset(&tbuf, 0, sizeof(tbuf)); |
1da177e4c Linux-2.6.12-rc2 |
613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 |
kernel_to_ipc64_perm(&sma->sem_perm, &tbuf.sem_perm); tbuf.sem_otime = sma->sem_otime; tbuf.sem_ctime = sma->sem_ctime; tbuf.sem_nsems = sma->sem_nsems; sem_unlock(sma); if (copy_semid_to_user (arg.buf, &tbuf, version)) return -EFAULT; return id; } default: return -EINVAL; } return err; out_unlock: sem_unlock(sma); return err; } |
e38935341 [PATCH] IPC names... |
630 631 |
static int semctl_main(struct ipc_namespace *ns, int semid, int semnum, int cmd, int version, union semun arg) |
1da177e4c Linux-2.6.12-rc2 |
632 633 634 635 636 637 638 |
{ struct sem_array *sma; struct sem* curr; int err; ushort fast_sem_io[SEMMSL_FAST]; ushort* sem_io = fast_sem_io; int nsems; |
023a53557 ipc: integrate ip... |
639 640 641 |
sma = sem_lock_check(ns, semid); if (IS_ERR(sma)) return PTR_ERR(sma); |
1da177e4c Linux-2.6.12-rc2 |
642 643 |
nsems = sma->sem_nsems; |
1da177e4c Linux-2.6.12-rc2 |
644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 |
err = -EACCES; if (ipcperms (&sma->sem_perm, (cmd==SETVAL||cmd==SETALL)?S_IWUGO:S_IRUGO)) goto out_unlock; err = security_sem_semctl(sma, cmd); if (err) goto out_unlock; err = -EACCES; switch (cmd) { case GETALL: { ushort __user *array = arg.array; int i; if(nsems > SEMMSL_FAST) { |
6ff379721 IPC/semaphores: c... |
660 |
sem_getref_and_unlock(sma); |
1da177e4c Linux-2.6.12-rc2 |
661 662 663 |
sem_io = ipc_alloc(sizeof(ushort)*nsems); if(sem_io == NULL) { |
6ff379721 IPC/semaphores: c... |
664 |
sem_putref(sma); |
1da177e4c Linux-2.6.12-rc2 |
665 666 |
return -ENOMEM; } |
6ff379721 IPC/semaphores: c... |
667 |
sem_lock_and_putref(sma); |
1da177e4c Linux-2.6.12-rc2 |
668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 |
if (sma->sem_perm.deleted) { sem_unlock(sma); err = -EIDRM; goto out_free; } } for (i = 0; i < sma->sem_nsems; i++) sem_io[i] = sma->sem_base[i].semval; sem_unlock(sma); err = 0; if(copy_to_user(array, sem_io, nsems*sizeof(ushort))) err = -EFAULT; goto out_free; } case SETALL: { int i; struct sem_undo *un; |
6ff379721 IPC/semaphores: c... |
687 |
sem_getref_and_unlock(sma); |
1da177e4c Linux-2.6.12-rc2 |
688 689 690 691 |
if(nsems > SEMMSL_FAST) { sem_io = ipc_alloc(sizeof(ushort)*nsems); if(sem_io == NULL) { |
6ff379721 IPC/semaphores: c... |
692 |
sem_putref(sma); |
1da177e4c Linux-2.6.12-rc2 |
693 694 695 696 697 |
return -ENOMEM; } } if (copy_from_user (sem_io, arg.array, nsems*sizeof(ushort))) { |
6ff379721 IPC/semaphores: c... |
698 |
sem_putref(sma); |
1da177e4c Linux-2.6.12-rc2 |
699 700 701 702 703 704 |
err = -EFAULT; goto out_free; } for (i = 0; i < nsems; i++) { if (sem_io[i] > SEMVMX) { |
6ff379721 IPC/semaphores: c... |
705 |
sem_putref(sma); |
1da177e4c Linux-2.6.12-rc2 |
706 707 708 709 |
err = -ERANGE; goto out_free; } } |
6ff379721 IPC/semaphores: c... |
710 |
sem_lock_and_putref(sma); |
1da177e4c Linux-2.6.12-rc2 |
711 712 713 714 715 716 717 718 |
if (sma->sem_perm.deleted) { sem_unlock(sma); err = -EIDRM; goto out_free; } for (i = 0; i < nsems; i++) sma->sem_base[i].semval = sem_io[i]; |
4daa28f6d ipc/sem.c: conver... |
719 720 721 |
assert_spin_locked(&sma->sem_perm.lock); list_for_each_entry(un, &sma->list_id, list_id) { |
1da177e4c Linux-2.6.12-rc2 |
722 723 |
for (i = 0; i < nsems; i++) un->semadj[i] = 0; |
4daa28f6d ipc/sem.c: conver... |
724 |
} |
1da177e4c Linux-2.6.12-rc2 |
725 726 727 728 729 730 |
sma->sem_ctime = get_seconds(); /* maybe some queued-up processes were waiting for this */ update_queue(sma); err = 0; goto out_unlock; } |
1da177e4c Linux-2.6.12-rc2 |
731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 |
/* GETVAL, GETPID, GETNCTN, GETZCNT, SETVAL: fall-through */ } err = -EINVAL; if(semnum < 0 || semnum >= nsems) goto out_unlock; curr = &sma->sem_base[semnum]; switch (cmd) { case GETVAL: err = curr->semval; goto out_unlock; case GETPID: err = curr->sempid; goto out_unlock; case GETNCNT: err = count_semncnt(sma,semnum); goto out_unlock; case GETZCNT: err = count_semzcnt(sma,semnum); goto out_unlock; case SETVAL: { int val = arg.val; struct sem_undo *un; |
4daa28f6d ipc/sem.c: conver... |
756 |
|
1da177e4c Linux-2.6.12-rc2 |
757 758 759 |
err = -ERANGE; if (val > SEMVMX || val < 0) goto out_unlock; |
4daa28f6d ipc/sem.c: conver... |
760 761 |
assert_spin_locked(&sma->sem_perm.lock); list_for_each_entry(un, &sma->list_id, list_id) |
1da177e4c Linux-2.6.12-rc2 |
762 |
un->semadj[semnum] = 0; |
4daa28f6d ipc/sem.c: conver... |
763 |
|
1da177e4c Linux-2.6.12-rc2 |
764 |
curr->semval = val; |
b488893a3 pid namespaces: c... |
765 |
curr->sempid = task_tgid_vnr(current); |
1da177e4c Linux-2.6.12-rc2 |
766 767 768 769 770 771 772 773 774 775 776 777 778 779 |
sma->sem_ctime = get_seconds(); /* maybe some queued-up processes were waiting for this */ update_queue(sma); err = 0; goto out_unlock; } } out_unlock: sem_unlock(sma); out_free: if(sem_io != fast_sem_io) ipc_free(sem_io, sizeof(ushort)*nsems); return err; } |
016d7132f IPC: get rid of t... |
780 781 |
static inline unsigned long copy_semid_from_user(struct semid64_ds *out, void __user *buf, int version) |
1da177e4c Linux-2.6.12-rc2 |
782 783 784 |
{ switch(version) { case IPC_64: |
016d7132f IPC: get rid of t... |
785 |
if (copy_from_user(out, buf, sizeof(*out))) |
1da177e4c Linux-2.6.12-rc2 |
786 |
return -EFAULT; |
1da177e4c Linux-2.6.12-rc2 |
787 |
return 0; |
1da177e4c Linux-2.6.12-rc2 |
788 789 790 791 792 793 |
case IPC_OLD: { struct semid_ds tbuf_old; if(copy_from_user(&tbuf_old, buf, sizeof(tbuf_old))) return -EFAULT; |
016d7132f IPC: get rid of t... |
794 795 796 |
out->sem_perm.uid = tbuf_old.sem_perm.uid; out->sem_perm.gid = tbuf_old.sem_perm.gid; out->sem_perm.mode = tbuf_old.sem_perm.mode; |
1da177e4c Linux-2.6.12-rc2 |
797 798 799 800 801 802 803 |
return 0; } default: return -EINVAL; } } |
522bb2a2b IPC/semaphores: m... |
804 805 806 807 808 |
/* * This function handles some semctl commands which require the rw_mutex * to be held in write mode. * NOTE: no locks must be held, the rw_mutex is taken inside this function. */ |
21a4826a7 IPC/semaphores: r... |
809 810 |
static int semctl_down(struct ipc_namespace *ns, int semid, int cmd, int version, union semun arg) |
1da177e4c Linux-2.6.12-rc2 |
811 812 813 |
{ struct sem_array *sma; int err; |
016d7132f IPC: get rid of t... |
814 |
struct semid64_ds semid64; |
1da177e4c Linux-2.6.12-rc2 |
815 816 817 |
struct kern_ipc_perm *ipcp; if(cmd == IPC_SET) { |
016d7132f IPC: get rid of t... |
818 |
if (copy_semid_from_user(&semid64, arg.buf, version)) |
1da177e4c Linux-2.6.12-rc2 |
819 |
return -EFAULT; |
1da177e4c Linux-2.6.12-rc2 |
820 |
} |
073115d6b [PATCH] Rework of... |
821 |
|
a5f75e7f2 IPC: consolidate ... |
822 823 824 |
ipcp = ipcctl_pre_down(&sem_ids(ns), semid, cmd, &semid64.sem_perm, 0); if (IS_ERR(ipcp)) return PTR_ERR(ipcp); |
073115d6b [PATCH] Rework of... |
825 |
|
a5f75e7f2 IPC: consolidate ... |
826 |
sma = container_of(ipcp, struct sem_array, sem_perm); |
1da177e4c Linux-2.6.12-rc2 |
827 828 829 830 831 832 833 |
err = security_sem_semctl(sma, cmd); if (err) goto out_unlock; switch(cmd){ case IPC_RMID: |
01b8b07a5 IPC: consolidate ... |
834 |
freeary(ns, ipcp); |
522bb2a2b IPC/semaphores: m... |
835 |
goto out_up; |
1da177e4c Linux-2.6.12-rc2 |
836 |
case IPC_SET: |
8f4a3809c IPC: introduce ip... |
837 |
ipc_update_perm(&semid64.sem_perm, ipcp); |
1da177e4c Linux-2.6.12-rc2 |
838 |
sma->sem_ctime = get_seconds(); |
1da177e4c Linux-2.6.12-rc2 |
839 840 |
break; default: |
1da177e4c Linux-2.6.12-rc2 |
841 |
err = -EINVAL; |
1da177e4c Linux-2.6.12-rc2 |
842 |
} |
1da177e4c Linux-2.6.12-rc2 |
843 844 845 |
out_unlock: sem_unlock(sma); |
522bb2a2b IPC/semaphores: m... |
846 847 |
out_up: up_write(&sem_ids(ns).rw_mutex); |
1da177e4c Linux-2.6.12-rc2 |
848 849 850 851 852 853 854 |
return err; } asmlinkage long sys_semctl (int semid, int semnum, int cmd, union semun arg) { int err = -EINVAL; int version; |
e38935341 [PATCH] IPC names... |
855 |
struct ipc_namespace *ns; |
1da177e4c Linux-2.6.12-rc2 |
856 857 858 859 860 |
if (semid < 0) return -EINVAL; version = ipc_parse_version(&cmd); |
e38935341 [PATCH] IPC names... |
861 |
ns = current->nsproxy->ipc_ns; |
1da177e4c Linux-2.6.12-rc2 |
862 863 864 865 |
switch(cmd) { case IPC_INFO: case SEM_INFO: |
4b9fcb0ec IPC/semaphores: c... |
866 |
case IPC_STAT: |
1da177e4c Linux-2.6.12-rc2 |
867 |
case SEM_STAT: |
4b9fcb0ec IPC/semaphores: c... |
868 |
err = semctl_nolock(ns, semid, cmd, version, arg); |
1da177e4c Linux-2.6.12-rc2 |
869 870 871 872 873 874 |
return err; case GETALL: case GETVAL: case GETPID: case GETNCNT: case GETZCNT: |
1da177e4c Linux-2.6.12-rc2 |
875 876 |
case SETVAL: case SETALL: |
e38935341 [PATCH] IPC names... |
877 |
err = semctl_main(ns,semid,semnum,cmd,version,arg); |
1da177e4c Linux-2.6.12-rc2 |
878 879 880 |
return err; case IPC_RMID: case IPC_SET: |
21a4826a7 IPC/semaphores: r... |
881 |
err = semctl_down(ns, semid, cmd, version, arg); |
1da177e4c Linux-2.6.12-rc2 |
882 883 884 885 886 |
return err; default: return -EINVAL; } } |
1da177e4c Linux-2.6.12-rc2 |
887 888 889 890 891 892 893 894 895 896 897 898 899 900 |
/* If the task doesn't already have a undo_list, then allocate one * here. We guarantee there is only one thread using this undo list, * and current is THE ONE * * If this allocation and assignment succeeds, but later * portions of this code fail, there is no need to free the sem_undo_list. * Just let it stay associated with the task, and it'll be freed later * at exit time. * * This can block, so callers must hold no locks. */ static inline int get_undo_list(struct sem_undo_list **undo_listp) { struct sem_undo_list *undo_list; |
1da177e4c Linux-2.6.12-rc2 |
901 902 903 |
undo_list = current->sysvsem.undo_list; if (!undo_list) { |
2453a3062 [PATCH] ipc: repl... |
904 |
undo_list = kzalloc(sizeof(*undo_list), GFP_KERNEL); |
1da177e4c Linux-2.6.12-rc2 |
905 906 |
if (undo_list == NULL) return -ENOMEM; |
00a5dfdb9 [PATCH] Fix semun... |
907 |
spin_lock_init(&undo_list->lock); |
1da177e4c Linux-2.6.12-rc2 |
908 |
atomic_set(&undo_list->refcnt, 1); |
4daa28f6d ipc/sem.c: conver... |
909 |
INIT_LIST_HEAD(&undo_list->list_proc); |
1da177e4c Linux-2.6.12-rc2 |
910 911 912 913 914 915 916 917 |
current->sysvsem.undo_list = undo_list; } *undo_listp = undo_list; return 0; } static struct sem_undo *lookup_undo(struct sem_undo_list *ulp, int semid) { |
380af1b33 ipc/sem.c: rewrit... |
918 |
struct sem_undo *walk; |
4daa28f6d ipc/sem.c: conver... |
919 |
|
380af1b33 ipc/sem.c: rewrit... |
920 |
list_for_each_entry_rcu(walk, &ulp->list_proc, list_proc) { |
4daa28f6d ipc/sem.c: conver... |
921 922 |
if (walk->semid == semid) return walk; |
1da177e4c Linux-2.6.12-rc2 |
923 |
} |
4daa28f6d ipc/sem.c: conver... |
924 |
return NULL; |
1da177e4c Linux-2.6.12-rc2 |
925 |
} |
4daa28f6d ipc/sem.c: conver... |
926 927 928 929 930 931 932 933 |
/** * find_alloc_undo - Lookup (and if not present create) undo array * @ns: namespace * @semid: semaphore array id * * The function looks up (and if not present creates) the undo structure. * The size of the undo structure depends on the size of the semaphore * array, thus the alloc path is not that straightforward. |
380af1b33 ipc/sem.c: rewrit... |
934 935 |
* Lifetime-rules: sem_undo is rcu-protected, on success, the function * performs a rcu_read_lock(). |
4daa28f6d ipc/sem.c: conver... |
936 937 |
*/ static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid) |
1da177e4c Linux-2.6.12-rc2 |
938 939 940 941 942 943 944 945 946 947 |
{ struct sem_array *sma; struct sem_undo_list *ulp; struct sem_undo *un, *new; int nsems; int error; error = get_undo_list(&ulp); if (error) return ERR_PTR(error); |
380af1b33 ipc/sem.c: rewrit... |
948 |
rcu_read_lock(); |
c530c6ac7 IPC: cleanup some... |
949 |
spin_lock(&ulp->lock); |
1da177e4c Linux-2.6.12-rc2 |
950 |
un = lookup_undo(ulp, semid); |
c530c6ac7 IPC: cleanup some... |
951 |
spin_unlock(&ulp->lock); |
1da177e4c Linux-2.6.12-rc2 |
952 953 |
if (likely(un!=NULL)) goto out; |
380af1b33 ipc/sem.c: rewrit... |
954 |
rcu_read_unlock(); |
1da177e4c Linux-2.6.12-rc2 |
955 956 |
/* no undo structure around - allocate one. */ |
4daa28f6d ipc/sem.c: conver... |
957 |
/* step 1: figure out the size of the semaphore array */ |
023a53557 ipc: integrate ip... |
958 959 960 |
sma = sem_lock_check(ns, semid); if (IS_ERR(sma)) return ERR_PTR(PTR_ERR(sma)); |
1da177e4c Linux-2.6.12-rc2 |
961 |
nsems = sma->sem_nsems; |
6ff379721 IPC/semaphores: c... |
962 |
sem_getref_and_unlock(sma); |
1da177e4c Linux-2.6.12-rc2 |
963 |
|
4daa28f6d ipc/sem.c: conver... |
964 |
/* step 2: allocate new undo structure */ |
4668edc33 [PATCH] kernel co... |
965 |
new = kzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems, GFP_KERNEL); |
1da177e4c Linux-2.6.12-rc2 |
966 |
if (!new) { |
6ff379721 IPC/semaphores: c... |
967 |
sem_putref(sma); |
1da177e4c Linux-2.6.12-rc2 |
968 969 |
return ERR_PTR(-ENOMEM); } |
1da177e4c Linux-2.6.12-rc2 |
970 |
|
380af1b33 ipc/sem.c: rewrit... |
971 |
/* step 3: Acquire the lock on semaphore array */ |
6ff379721 IPC/semaphores: c... |
972 |
sem_lock_and_putref(sma); |
1da177e4c Linux-2.6.12-rc2 |
973 974 |
if (sma->sem_perm.deleted) { sem_unlock(sma); |
1da177e4c Linux-2.6.12-rc2 |
975 976 977 978 |
kfree(new); un = ERR_PTR(-EIDRM); goto out; } |
380af1b33 ipc/sem.c: rewrit... |
979 980 981 982 983 984 985 986 987 988 |
spin_lock(&ulp->lock); /* * step 4: check for races: did someone else allocate the undo struct? */ un = lookup_undo(ulp, semid); if (un) { kfree(new); goto success; } |
4daa28f6d ipc/sem.c: conver... |
989 990 |
/* step 5: initialize & link new undo structure */ new->semadj = (short *) &new[1]; |
380af1b33 ipc/sem.c: rewrit... |
991 |
new->ulp = ulp; |
4daa28f6d ipc/sem.c: conver... |
992 993 |
new->semid = semid; assert_spin_locked(&ulp->lock); |
380af1b33 ipc/sem.c: rewrit... |
994 |
list_add_rcu(&new->list_proc, &ulp->list_proc); |
4daa28f6d ipc/sem.c: conver... |
995 996 |
assert_spin_locked(&sma->sem_perm.lock); list_add(&new->list_id, &sma->list_id); |
380af1b33 ipc/sem.c: rewrit... |
997 |
un = new; |
4daa28f6d ipc/sem.c: conver... |
998 |
|
380af1b33 ipc/sem.c: rewrit... |
999 |
success: |
c530c6ac7 IPC: cleanup some... |
1000 |
spin_unlock(&ulp->lock); |
380af1b33 ipc/sem.c: rewrit... |
1001 1002 |
rcu_read_lock(); sem_unlock(sma); |
1da177e4c Linux-2.6.12-rc2 |
1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 |
out: return un; } asmlinkage long sys_semtimedop(int semid, struct sembuf __user *tsops, unsigned nsops, const struct timespec __user *timeout) { int error = -EINVAL; struct sem_array *sma; struct sembuf fast_sops[SEMOPM_FAST]; struct sembuf* sops = fast_sops, *sop; struct sem_undo *un; |
b78755abc [PATCH] ipcsem: r... |
1015 |
int undos = 0, alter = 0, max; |
1da177e4c Linux-2.6.12-rc2 |
1016 1017 |
struct sem_queue queue; unsigned long jiffies_left = 0; |
e38935341 [PATCH] IPC names... |
1018 1019 1020 |
struct ipc_namespace *ns; ns = current->nsproxy->ipc_ns; |
1da177e4c Linux-2.6.12-rc2 |
1021 1022 1023 |
if (nsops < 1 || semid < 0) return -EINVAL; |
e38935341 [PATCH] IPC names... |
1024 |
if (nsops > ns->sc_semopm) |
1da177e4c Linux-2.6.12-rc2 |
1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 |
return -E2BIG; if(nsops > SEMOPM_FAST) { sops = kmalloc(sizeof(*sops)*nsops,GFP_KERNEL); if(sops==NULL) return -ENOMEM; } if (copy_from_user (sops, tsops, nsops * sizeof(*tsops))) { error=-EFAULT; goto out_free; } if (timeout) { struct timespec _timeout; if (copy_from_user(&_timeout, timeout, sizeof(*timeout))) { error = -EFAULT; goto out_free; } if (_timeout.tv_sec < 0 || _timeout.tv_nsec < 0 || _timeout.tv_nsec >= 1000000000L) { error = -EINVAL; goto out_free; } jiffies_left = timespec_to_jiffies(&_timeout); } max = 0; for (sop = sops; sop < sops + nsops; sop++) { if (sop->sem_num >= max) max = sop->sem_num; if (sop->sem_flg & SEM_UNDO) |
b78755abc [PATCH] ipcsem: r... |
1053 1054 |
undos = 1; if (sop->sem_op != 0) |
1da177e4c Linux-2.6.12-rc2 |
1055 1056 |
alter = 1; } |
1da177e4c Linux-2.6.12-rc2 |
1057 |
|
1da177e4c Linux-2.6.12-rc2 |
1058 |
if (undos) { |
4daa28f6d ipc/sem.c: conver... |
1059 |
un = find_alloc_undo(ns, semid); |
1da177e4c Linux-2.6.12-rc2 |
1060 1061 1062 1063 1064 1065 |
if (IS_ERR(un)) { error = PTR_ERR(un); goto out_free; } } else un = NULL; |
023a53557 ipc: integrate ip... |
1066 1067 |
sma = sem_lock_check(ns, semid); if (IS_ERR(sma)) { |
380af1b33 ipc/sem.c: rewrit... |
1068 1069 |
if (un) rcu_read_unlock(); |
023a53557 ipc: integrate ip... |
1070 |
error = PTR_ERR(sma); |
1da177e4c Linux-2.6.12-rc2 |
1071 |
goto out_free; |
023a53557 ipc: integrate ip... |
1072 |
} |
1da177e4c Linux-2.6.12-rc2 |
1073 |
/* |
4daa28f6d ipc/sem.c: conver... |
1074 |
* semid identifiers are not unique - find_alloc_undo may have |
1da177e4c Linux-2.6.12-rc2 |
1075 |
* allocated an undo structure, it was invalidated by an RMID |
4daa28f6d ipc/sem.c: conver... |
1076 |
* and now a new array with received the same id. Check and fail. |
380af1b33 ipc/sem.c: rewrit... |
1077 1078 |
* This case can be detected checking un->semid. The existance of * "un" itself is guaranteed by rcu. |
1da177e4c Linux-2.6.12-rc2 |
1079 |
*/ |
4daa28f6d ipc/sem.c: conver... |
1080 |
error = -EIDRM; |
380af1b33 ipc/sem.c: rewrit... |
1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 |
if (un) { if (un->semid == -1) { rcu_read_unlock(); goto out_unlock_free; } else { /* * rcu lock can be released, "un" cannot disappear: * - sem_lock is acquired, thus IPC_RMID is * impossible. * - exit_sem is impossible, it always operates on * current (or a dead task). */ rcu_read_unlock(); } } |
4daa28f6d ipc/sem.c: conver... |
1097 |
|
1da177e4c Linux-2.6.12-rc2 |
1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 |
error = -EFBIG; if (max >= sma->sem_nsems) goto out_unlock_free; error = -EACCES; if (ipcperms(&sma->sem_perm, alter ? S_IWUGO : S_IRUGO)) goto out_unlock_free; error = security_sem_semop(sma, sops, nsops, alter); if (error) goto out_unlock_free; |
b488893a3 pid namespaces: c... |
1109 |
error = try_atomic_semop (sma, sops, nsops, un, task_tgid_vnr(current)); |
1da177e4c Linux-2.6.12-rc2 |
1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 |
if (error <= 0) { if (alter && error == 0) update_queue (sma); goto out_unlock_free; } /* We need to sleep on this operation, so we put the current * task into the pending queue and go to sleep. */ |
1da177e4c Linux-2.6.12-rc2 |
1120 1121 1122 |
queue.sops = sops; queue.nsops = nsops; queue.undo = un; |
b488893a3 pid namespaces: c... |
1123 |
queue.pid = task_tgid_vnr(current); |
1da177e4c Linux-2.6.12-rc2 |
1124 1125 |
queue.alter = alter; if (alter) |
a1193f8ec ipc/sem.c: conver... |
1126 |
list_add_tail(&queue.list, &sma->sem_pending); |
1da177e4c Linux-2.6.12-rc2 |
1127 |
else |
a1193f8ec ipc/sem.c: conver... |
1128 |
list_add(&queue.list, &sma->sem_pending); |
1da177e4c Linux-2.6.12-rc2 |
1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 |
queue.status = -EINTR; queue.sleeper = current; current->state = TASK_INTERRUPTIBLE; sem_unlock(sma); if (timeout) jiffies_left = schedule_timeout(jiffies_left); else schedule(); error = queue.status; while(unlikely(error == IN_WAKEUP)) { cpu_relax(); error = queue.status; } if (error != -EINTR) { /* fast path: update_queue already obtained all requested * resources */ goto out_free; } |
e38935341 [PATCH] IPC names... |
1151 |
sma = sem_lock(ns, semid); |
023a53557 ipc: integrate ip... |
1152 |
if (IS_ERR(sma)) { |
1da177e4c Linux-2.6.12-rc2 |
1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 |
error = -EIDRM; goto out_free; } /* * If queue.status != -EINTR we are woken up by another process */ error = queue.status; if (error != -EINTR) { goto out_unlock_free; } /* * If an interrupt occurred we have to clean up the queue */ if (timeout && jiffies_left == 0) error = -EAGAIN; |
a1193f8ec ipc/sem.c: conver... |
1170 |
list_del(&queue.list); |
1da177e4c Linux-2.6.12-rc2 |
1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 |
goto out_unlock_free; out_unlock_free: sem_unlock(sma); out_free: if(sops != fast_sops) kfree(sops); return error; } asmlinkage long sys_semop (int semid, struct sembuf __user *tsops, unsigned nsops) { return sys_semtimedop(semid, tsops, nsops, NULL); } /* If CLONE_SYSVSEM is set, establish sharing of SEM_UNDO state between * parent and child tasks. |
1da177e4c Linux-2.6.12-rc2 |
1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 |
*/ int copy_semundo(unsigned long clone_flags, struct task_struct *tsk) { struct sem_undo_list *undo_list; int error; if (clone_flags & CLONE_SYSVSEM) { error = get_undo_list(&undo_list); if (error) return error; |
1da177e4c Linux-2.6.12-rc2 |
1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 |
atomic_inc(&undo_list->refcnt); tsk->sysvsem.undo_list = undo_list; } else tsk->sysvsem.undo_list = NULL; return 0; } /* * add semadj values to semaphores, free undo structures. * undo structures are not freed when semaphore arrays are destroyed * so some of them may be out of date. * IMPLEMENTATION NOTE: There is some confusion over whether the * set of adjustments that needs to be done should be done in an atomic * manner or not. That is, if we are attempting to decrement the semval * should we queue up and wait until we can do so legally? * The original implementation attempted to do this (queue and wait). * The current implementation does not do so. The POSIX standard * and SVID should be consulted to determine what behavior is mandated. */ void exit_sem(struct task_struct *tsk) { |
4daa28f6d ipc/sem.c: conver... |
1221 |
struct sem_undo_list *ulp; |
1da177e4c Linux-2.6.12-rc2 |
1222 |
|
4daa28f6d ipc/sem.c: conver... |
1223 1224 |
ulp = tsk->sysvsem.undo_list; if (!ulp) |
1da177e4c Linux-2.6.12-rc2 |
1225 |
return; |
9edff4ab1 ipc: sysvsem: imp... |
1226 |
tsk->sysvsem.undo_list = NULL; |
1da177e4c Linux-2.6.12-rc2 |
1227 |
|
4daa28f6d ipc/sem.c: conver... |
1228 |
if (!atomic_dec_and_test(&ulp->refcnt)) |
1da177e4c Linux-2.6.12-rc2 |
1229 |
return; |
380af1b33 ipc/sem.c: rewrit... |
1230 |
for (;;) { |
1da177e4c Linux-2.6.12-rc2 |
1231 |
struct sem_array *sma; |
380af1b33 ipc/sem.c: rewrit... |
1232 1233 |
struct sem_undo *un; int semid; |
4daa28f6d ipc/sem.c: conver... |
1234 |
int i; |
380af1b33 ipc/sem.c: rewrit... |
1235 1236 1237 1238 1239 1240 1241 1242 |
rcu_read_lock(); un = list_entry(rcu_dereference(ulp->list_proc.next), struct sem_undo, list_proc); if (&un->list_proc == &ulp->list_proc) semid = -1; else semid = un->semid; rcu_read_unlock(); |
4daa28f6d ipc/sem.c: conver... |
1243 |
|
380af1b33 ipc/sem.c: rewrit... |
1244 1245 |
if (semid == -1) break; |
1da177e4c Linux-2.6.12-rc2 |
1246 |
|
380af1b33 ipc/sem.c: rewrit... |
1247 |
sma = sem_lock_check(tsk->nsproxy->ipc_ns, un->semid); |
1da177e4c Linux-2.6.12-rc2 |
1248 |
|
380af1b33 ipc/sem.c: rewrit... |
1249 1250 1251 |
/* exit_sem raced with IPC_RMID, nothing to do */ if (IS_ERR(sma)) continue; |
1da177e4c Linux-2.6.12-rc2 |
1252 |
|
380af1b33 ipc/sem.c: rewrit... |
1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 |
un = lookup_undo(ulp, semid); if (un == NULL) { /* exit_sem raced with IPC_RMID+semget() that created * exactly the same semid. Nothing to do. */ sem_unlock(sma); continue; } /* remove un from the linked lists */ |
4daa28f6d ipc/sem.c: conver... |
1263 1264 |
assert_spin_locked(&sma->sem_perm.lock); list_del(&un->list_id); |
380af1b33 ipc/sem.c: rewrit... |
1265 1266 1267 |
spin_lock(&ulp->lock); list_del_rcu(&un->list_proc); spin_unlock(&ulp->lock); |
4daa28f6d ipc/sem.c: conver... |
1268 1269 |
/* perform adjustments registered in un */ for (i = 0; i < sma->sem_nsems; i++) { |
5f921ae96 [PATCH] sem2mutex... |
1270 |
struct sem * semaphore = &sma->sem_base[i]; |
4daa28f6d ipc/sem.c: conver... |
1271 1272 |
if (un->semadj[i]) { semaphore->semval += un->semadj[i]; |
1da177e4c Linux-2.6.12-rc2 |
1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 |
/* * Range checks of the new semaphore value, * not defined by sus: * - Some unices ignore the undo entirely * (e.g. HP UX 11i 11.22, Tru64 V5.1) * - some cap the value (e.g. FreeBSD caps * at 0, but doesn't enforce SEMVMX) * * Linux caps the semaphore value, both at 0 * and at SEMVMX. * * Manfred <manfred@colorfullife.com> */ |
5f921ae96 [PATCH] sem2mutex... |
1286 1287 1288 1289 |
if (semaphore->semval < 0) semaphore->semval = 0; if (semaphore->semval > SEMVMX) semaphore->semval = SEMVMX; |
b488893a3 pid namespaces: c... |
1290 |
semaphore->sempid = task_tgid_vnr(current); |
1da177e4c Linux-2.6.12-rc2 |
1291 1292 1293 1294 1295 |
} } sma->sem_otime = get_seconds(); /* maybe some queued-up processes were waiting for this */ update_queue(sma); |
1da177e4c Linux-2.6.12-rc2 |
1296 |
sem_unlock(sma); |
380af1b33 ipc/sem.c: rewrit... |
1297 1298 |
call_rcu(&un->rcu, free_un); |
1da177e4c Linux-2.6.12-rc2 |
1299 |
} |
4daa28f6d ipc/sem.c: conver... |
1300 |
kfree(ulp); |
1da177e4c Linux-2.6.12-rc2 |
1301 1302 1303 |
} #ifdef CONFIG_PROC_FS |
19b4946ca [PATCH] ipc: conv... |
1304 |
static int sysvipc_sem_proc_show(struct seq_file *s, void *it) |
1da177e4c Linux-2.6.12-rc2 |
1305 |
{ |
19b4946ca [PATCH] ipc: conv... |
1306 1307 1308 1309 1310 1311 |
struct sem_array *sma = it; return seq_printf(s, "%10d %10d %4o %10lu %5u %5u %5u %5u %10lu %10lu ", sma->sem_perm.key, |
7ca7e564e ipc: store ipcs i... |
1312 |
sma->sem_perm.id, |
19b4946ca [PATCH] ipc: conv... |
1313 1314 1315 1316 1317 1318 1319 1320 |
sma->sem_perm.mode, sma->sem_nsems, sma->sem_perm.uid, sma->sem_perm.gid, sma->sem_perm.cuid, sma->sem_perm.cgid, sma->sem_otime, sma->sem_ctime); |
1da177e4c Linux-2.6.12-rc2 |
1321 1322 |
} #endif |