diff options
Diffstat (limited to 'ANDROID_3.4.5/ipc/sem.c')
| -rw-r--r-- | ANDROID_3.4.5/ipc/sem.c | 1695 |
1 files changed, 0 insertions, 1695 deletions
diff --git a/ANDROID_3.4.5/ipc/sem.c b/ANDROID_3.4.5/ipc/sem.c deleted file mode 100644 index 5215a814..00000000 --- a/ANDROID_3.4.5/ipc/sem.c +++ /dev/null @@ -1,1695 +0,0 @@ -/* - * linux/ipc/sem.c - * Copyright (C) 1992 Krishna Balasubramanian - * Copyright (C) 1995 Eric Schenk, Bruno Haible - * - * /proc/sysvipc/sem support (c) 1999 Dragos Acostachioaie <dragos@iname.com> - * - * SMP-threaded, sysctl's added - * (c) 1999 Manfred Spraul <manfred@colorfullife.com> - * Enforced range limit on SEM_UNDO - * (c) 2001 Red Hat Inc - * Lockless wakeup - * (c) 2003 Manfred Spraul <manfred@colorfullife.com> - * Further wakeup optimizations, documentation - * (c) 2010 Manfred Spraul <manfred@colorfullife.com> - * - * support for audit of ipc object properties and permission changes - * Dustin Kirkland <dustin.kirkland@us.ibm.com> - * - * namespaces support - * OpenVZ, SWsoft Inc. - * Pavel Emelianov <xemul@openvz.org> - * - * Implementation notes: (May 2010) - * This file implements System V semaphores. - * - * User space visible behavior: - * - FIFO ordering for semop() operations (just FIFO, not starvation - * protection) - * - multiple semaphore operations that alter the same semaphore in - * one semop() are handled. - * - sem_ctime (time of last semctl()) is updated in the IPC_SET, SETVAL and - * SETALL calls. - * - two Linux specific semctl() commands: SEM_STAT, SEM_INFO. - * - undo adjustments at process exit are limited to 0..SEMVMX. - * - namespace are supported. - * - SEMMSL, SEMMNS, SEMOPM and SEMMNI can be configured at runtine by writing - * to /proc/sys/kernel/sem. - * - statistics about the usage are reported in /proc/sysvipc/sem. - * - * Internals: - * - scalability: - * - all global variables are read-mostly. - * - semop() calls and semctl(RMID) are synchronized by RCU. - * - most operations do write operations (actually: spin_lock calls) to - * the per-semaphore array structure. - * Thus: Perfect SMP scaling between independent semaphore arrays. - * If multiple semaphores in one array are used, then cache line - * trashing on the semaphore array spinlock will limit the scaling. - * - semncnt and semzcnt are calculated on demand in count_semncnt() and - * count_semzcnt() - * - the task that performs a successful semop() scans the list of all - * sleeping tasks and completes any pending operations that can be fulfilled. - * Semaphores are actively given to waiting tasks (necessary for FIFO). - * (see update_queue()) - * - To improve the scalability, the actual wake-up calls are performed after - * dropping all locks. (see wake_up_sem_queue_prepare(), - * wake_up_sem_queue_do()) - * - All work is done by the waker, the woken up task does not have to do - * anything - not even acquiring a lock or dropping a refcount. - * - A woken up task may not even touch the semaphore array anymore, it may - * have been destroyed already by a semctl(RMID). - * - The synchronizations between wake-ups due to a timeout/signal and a - * wake-up due to a completed semaphore operation is achieved by using an - * intermediate state (IN_WAKEUP). - * - UNDO values are stored in an array (one per process and per - * semaphore array, lazily allocated). For backwards compatibility, multiple - * modes for the UNDO variables are supported (per process, per thread) - * (see copy_semundo, CLONE_SYSVSEM) - * - There are two lists of the pending operations: a per-array list - * and per-semaphore list (stored in the array). This allows to achieve FIFO - * ordering without always scanning all pending operations. - * The worst-case behavior is nevertheless O(N^2) for N wakeups. - */ - -#include <linux/slab.h> -#include <linux/spinlock.h> -#include <linux/init.h> -#include <linux/proc_fs.h> -#include <linux/time.h> -#include <linux/security.h> -#include <linux/syscalls.h> -#include <linux/audit.h> -#include <linux/capability.h> -#include <linux/seq_file.h> -#include <linux/rwsem.h> -#include <linux/nsproxy.h> -#include <linux/ipc_namespace.h> - -#include <asm/uaccess.h> -#include "util.h" - -/* One semaphore structure for each semaphore in the system. */ -struct sem { - int semval; /* current value */ - int sempid; /* pid of last operation */ - struct list_head sem_pending; /* pending single-sop operations */ -}; - -/* One queue for each sleeping process in the system. */ -struct sem_queue { - struct list_head simple_list; /* queue of pending operations */ - struct list_head list; /* queue of pending operations */ - struct task_struct *sleeper; /* this process */ - struct sem_undo *undo; /* undo structure */ - int pid; /* process id of requesting process */ - int status; /* completion status of operation */ - struct sembuf *sops; /* array of pending operations */ - int nsops; /* number of operations */ - int alter; /* does *sops alter the array? */ -}; - -/* Each task has a list of undo requests. They are executed automatically - * when the process exits. - */ -struct sem_undo { - struct list_head list_proc; /* per-process list: * - * all undos from one process - * rcu protected */ - struct rcu_head rcu; /* rcu struct for sem_undo */ - struct sem_undo_list *ulp; /* back ptr to sem_undo_list */ - struct list_head list_id; /* per semaphore array list: - * all undos for one array */ - int semid; /* semaphore set identifier */ - short *semadj; /* array of adjustments */ - /* one per semaphore */ -}; - -/* sem_undo_list controls shared access to the list of sem_undo structures - * that may be shared among all a CLONE_SYSVSEM task group. - */ -struct sem_undo_list { - atomic_t refcnt; - spinlock_t lock; - struct list_head list_proc; -}; - - -#define sem_ids(ns) ((ns)->ids[IPC_SEM_IDS]) - -#define sem_unlock(sma) ipc_unlock(&(sma)->sem_perm) -#define sem_checkid(sma, semid) ipc_checkid(&sma->sem_perm, semid) - -static int newary(struct ipc_namespace *, struct ipc_params *); -static void freeary(struct ipc_namespace *, struct kern_ipc_perm *); -#ifdef CONFIG_PROC_FS -static int sysvipc_sem_proc_show(struct seq_file *s, void *it); -#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. - * - */ - -#define sc_semmsl sem_ctls[0] -#define sc_semmns sem_ctls[1] -#define sc_semopm sem_ctls[2] -#define sc_semmni sem_ctls[3] - -void sem_init_ns(struct ipc_namespace *ns) -{ - ns->sc_semmsl = SEMMSL; - ns->sc_semmns = SEMMNS; - ns->sc_semopm = SEMOPM; - ns->sc_semmni = SEMMNI; - ns->used_sems = 0; - ipc_init_ids(&ns->ids[IPC_SEM_IDS]); -} - -#ifdef CONFIG_IPC_NS -void sem_exit_ns(struct ipc_namespace *ns) -{ - free_ipcs(ns, &sem_ids(ns), freeary); - idr_destroy(&ns->ids[IPC_SEM_IDS].ipcs_idr); -} -#endif - -void __init sem_init (void) -{ - sem_init_ns(&init_ipc_ns); - ipc_init_proc_interface("sysvipc/sem", - " key semid perms nsems uid gid cuid cgid otime ctime\n", - IPC_SEM_IDS, sysvipc_sem_proc_show); -} - -/* - * sem_lock_(check_) routines are called in the paths where the rw_mutex - * is not held. - */ -static inline struct sem_array *sem_lock(struct ipc_namespace *ns, int id) -{ - struct kern_ipc_perm *ipcp = ipc_lock(&sem_ids(ns), id); - - if (IS_ERR(ipcp)) - return (struct sem_array *)ipcp; - - return container_of(ipcp, struct sem_array, sem_perm); -} - -static inline struct sem_array *sem_lock_check(struct ipc_namespace *ns, - int id) -{ - struct kern_ipc_perm *ipcp = ipc_lock_check(&sem_ids(ns), id); - - if (IS_ERR(ipcp)) - return (struct sem_array *)ipcp; - - return container_of(ipcp, struct sem_array, sem_perm); -} - -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); -} - -static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s) -{ - ipc_rmid(&sem_ids(ns), &s->sem_perm); -} - -/* - * 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 - * performing any operation on the sem array. - * * 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 - -/** - * newary - Create a new semaphore set - * @ns: namespace - * @params: ptr to the structure that contains key, semflg and nsems - * - * Called with sem_ids.rw_mutex held (as a writer) - */ - -static int newary(struct ipc_namespace *ns, struct ipc_params *params) -{ - int id; - int retval; - struct sem_array *sma; - int size; - key_t key = params->key; - int nsems = params->u.nsems; - int semflg = params->flg; - int i; - - if (!nsems) - return -EINVAL; - if (ns->used_sems + nsems > ns->sc_semmns) - 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; - } - - id = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni); - if (id < 0) { - security_sem_free(sma); - ipc_rcu_putref(sma); - return id; - } - ns->used_sems += nsems; - - sma->sem_base = (struct sem *) &sma[1]; - - for (i = 0; i < nsems; i++) - INIT_LIST_HEAD(&sma->sem_base[i].sem_pending); - - sma->complex_count = 0; - INIT_LIST_HEAD(&sma->sem_pending); - INIT_LIST_HEAD(&sma->list_id); - sma->sem_nsems = nsems; - sma->sem_ctime = get_seconds(); - sem_unlock(sma); - - return sma->sem_perm.id; -} - - -/* - * Called with sem_ids.rw_mutex and ipcp locked. - */ -static inline int sem_security(struct kern_ipc_perm *ipcp, int semflg) -{ - struct sem_array *sma; - - sma = container_of(ipcp, struct sem_array, sem_perm); - return security_sem_associate(sma, semflg); -} - -/* - * Called with sem_ids.rw_mutex and ipcp locked. - */ -static inline int sem_more_checks(struct kern_ipc_perm *ipcp, - struct ipc_params *params) -{ - struct sem_array *sma; - - sma = container_of(ipcp, struct sem_array, sem_perm); - if (params->u.nsems > sma->sem_nsems) - return -EINVAL; - - return 0; -} - -SYSCALL_DEFINE3(semget, key_t, key, int, nsems, int, semflg) -{ - struct ipc_namespace *ns; - struct ipc_ops sem_ops; - struct ipc_params sem_params; - - ns = current->nsproxy->ipc_ns; - - if (nsems < 0 || nsems > ns->sc_semmsl) - return -EINVAL; - - 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; - - return ipcget(ns, &sem_ids(ns), &sem_ops, &sem_params); -} - -/* - * 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--; - } - - 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; -} - -/** wake_up_sem_queue_prepare(q, error): Prepare wake-up - * @q: queue entry that must be signaled - * @error: Error value for the signal - * - * Prepare the wake-up of the queue entry q. - */ -static void wake_up_sem_queue_prepare(struct list_head *pt, - struct sem_queue *q, int error) -{ - if (list_empty(pt)) { - /* - * Hold preempt off so that we don't get preempted and have the - * wakee busy-wait until we're scheduled back on. - */ - preempt_disable(); - } - q->status = IN_WAKEUP; - q->pid = error; - - list_add_tail(&q->simple_list, pt); -} - -/** - * wake_up_sem_queue_do(pt) - do the actual wake-up - * @pt: list of tasks to be woken up - * - * Do the actual wake-up. - * The function is called without any locks held, thus the semaphore array - * could be destroyed already and the tasks can disappear as soon as the - * status is set to the actual return code. - */ -static void wake_up_sem_queue_do(struct list_head *pt) -{ - struct sem_queue *q, *t; - int did_something; - - did_something = !list_empty(pt); - list_for_each_entry_safe(q, t, pt, simple_list) { - wake_up_process(q->sleeper); - /* q can disappear immediately after writing q->status. */ - smp_wmb(); - q->status = q->pid; - } - if (did_something) - preempt_enable(); -} - -static void unlink_queue(struct sem_array *sma, struct sem_queue *q) -{ - list_del(&q->list); - if (q->nsops == 1) - list_del(&q->simple_list); - else - sma->complex_count--; -} - -/** check_restart(sma, q) - * @sma: semaphore array - * @q: the operation that just completed - * - * update_queue is O(N^2) when it restarts scanning the whole queue of - * waiting operations. Therefore this function checks if the restart is - * really necessary. It is called after a previously waiting operation - * was completed. - */ -static int check_restart(struct sem_array *sma, struct sem_queue *q) -{ - struct sem *curr; - struct sem_queue *h; - - /* if the operation didn't modify the array, then no restart */ - if (q->alter == 0) - return 0; - - /* pending complex operations are too difficult to analyse */ - if (sma->complex_count) - return 1; - - /* we were a sleeping complex operation. Too difficult */ - if (q->nsops > 1) - return 1; - - curr = sma->sem_base + q->sops[0].sem_num; - - /* No-one waits on this queue */ - if (list_empty(&curr->sem_pending)) - return 0; - - /* the new semaphore value */ - if (curr->semval) { - /* It is impossible that someone waits for the new value: - * - q is a previously sleeping simple operation that - * altered the array. It must be a decrement, because - * simple increments never sleep. - * - The value is not 0, thus wait-for-zero won't proceed. - * - If there are older (higher priority) decrements - * in the queue, then they have observed the original - * semval value and couldn't proceed. The operation - * decremented to value - thus they won't proceed either. - */ - BUG_ON(q->sops[0].sem_op >= 0); - return 0; - } - /* - * semval is 0. Check if there are wait-for-zero semops. - * They must be the first entries in the per-semaphore simple queue - */ - h = list_first_entry(&curr->sem_pending, struct sem_queue, simple_list); - BUG_ON(h->nsops != 1); - BUG_ON(h->sops[0].sem_num != q->sops[0].sem_num); - - /* Yes, there is a wait-for-zero semop. Restart */ - if (h->sops[0].sem_op == 0) - return 1; - - /* Again - no-one is waiting for the new value. */ - return 0; -} - - -/** - * update_queue(sma, semnum): Look for tasks that can be completed. - * @sma: semaphore array. - * @semnum: semaphore that was modified. - * @pt: list head for the tasks that must be woken up. - * - * update_queue must be called after a semaphore in a semaphore array - * was modified. If multiple semaphore were modified, then @semnum - * must be set to -1. - * The tasks that must be woken up are added to @pt. The return code - * is stored in q->pid. - * The function return 1 if at least one semop was completed successfully. - */ -static int update_queue(struct sem_array *sma, int semnum, struct list_head *pt) -{ - struct sem_queue *q; - struct list_head *walk; - struct list_head *pending_list; - int offset; - int semop_completed = 0; - - /* if there are complex operations around, then knowing the semaphore - * that was modified doesn't help us. Assume that multiple semaphores - * were modified. - */ - if (sma->complex_count) - semnum = -1; - - if (semnum == -1) { - pending_list = &sma->sem_pending; - offset = offsetof(struct sem_queue, list); - } else { - pending_list = &sma->sem_base[semnum].sem_pending; - offset = offsetof(struct sem_queue, simple_list); - } - -again: - walk = pending_list->next; - while (walk != pending_list) { - int error, restart; - - q = (struct sem_queue *)((char *)walk - offset); - walk = walk->next; - - /* If we are scanning the single sop, per-semaphore list of - * one semaphore and that semaphore is 0, then it is not - * necessary to scan the "alter" entries: simple increments - * that affect only one entry succeed immediately and cannot - * be in the per semaphore pending queue, and decrements - * cannot be successful if the value is already 0. - */ - if (semnum != -1 && sma->sem_base[semnum].semval == 0 && - q->alter) - break; - - error = try_atomic_semop(sma, q->sops, q->nsops, - q->undo, q->pid); - - /* Does q->sleeper still need to sleep? */ - if (error > 0) - continue; - - unlink_queue(sma, q); - - if (error) { - restart = 0; - } else { - semop_completed = 1; - restart = check_restart(sma, q); - } - - wake_up_sem_queue_prepare(pt, q, error); - if (restart) - goto again; - } - return semop_completed; -} - -/** - * do_smart_update(sma, sops, nsops, otime, pt) - optimized update_queue - * @sma: semaphore array - * @sops: operations that were performed - * @nsops: number of operations - * @otime: force setting otime - * @pt: list head of the tasks that must be woken up. - * - * do_smart_update() does the required called to update_queue, based on the - * actual changes that were performed on the semaphore array. - * Note that the function does not do the actual wake-up: the caller is - * responsible for calling wake_up_sem_queue_do(@pt). - * It is safe to perform this call after dropping all locks. - */ -static void do_smart_update(struct sem_array *sma, struct sembuf *sops, int nsops, - int otime, struct list_head *pt) -{ - int i; - - if (sma->complex_count || sops == NULL) { - if (update_queue(sma, -1, pt)) - otime = 1; - goto done; - } - - for (i = 0; i < nsops; i++) { - if (sops[i].sem_op > 0 || - (sops[i].sem_op < 0 && - sma->sem_base[sops[i].sem_num].semval == 0)) - if (update_queue(sma, sops[i].sem_num, pt)) - otime = 1; - } -done: - if (otime) - sma->sem_otime = get_seconds(); -} - - -/* 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; - list_for_each_entry(q, &sma->sem_pending, list) { - 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; -} - -static int count_semzcnt (struct sem_array * sma, ushort semnum) -{ - int semzcnt; - struct sem_queue * q; - - semzcnt = 0; - list_for_each_entry(q, &sma->sem_pending, list) { - 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; -} - -/* 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. - */ -static void freeary(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp) -{ - struct sem_undo *un, *tu; - struct sem_queue *q, *tq; - struct sem_array *sma = container_of(ipcp, struct sem_array, sem_perm); - struct list_head tasks; - - /* Free the existing undo structures for this semaphore set. */ - assert_spin_locked(&sma->sem_perm.lock); - list_for_each_entry_safe(un, tu, &sma->list_id, list_id) { - list_del(&un->list_id); - spin_lock(&un->ulp->lock); - un->semid = -1; - list_del_rcu(&un->list_proc); - spin_unlock(&un->ulp->lock); - kfree_rcu(un, rcu); - } - - /* Wake up all pending processes and let them fail with EIDRM. */ - INIT_LIST_HEAD(&tasks); - list_for_each_entry_safe(q, tq, &sma->sem_pending, list) { - unlink_queue(sma, q); - wake_up_sem_queue_prepare(&tasks, q, -EIDRM); - } - - /* Remove the semaphore set from the IDR */ - sem_rmid(ns, sma); - sem_unlock(sma); - - wake_up_sem_queue_do(&tasks); - ns->used_sems -= sma->sem_nsems; - 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; - - memset(&out, 0, sizeof(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; - } -} - -static int semctl_nolock(struct ipc_namespace *ns, int semid, - int cmd, int version, union semun arg) -{ - int err; - 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)); - seminfo.semmni = ns->sc_semmni; - seminfo.semmns = ns->sc_semmns; - seminfo.semmsl = ns->sc_semmsl; - seminfo.semopm = ns->sc_semopm; - seminfo.semvmx = SEMVMX; - seminfo.semmnu = SEMMNU; - seminfo.semmap = SEMMAP; - seminfo.semume = SEMUME; - down_read(&sem_ids(ns).rw_mutex); - if (cmd == SEM_INFO) { - seminfo.semusz = sem_ids(ns).in_use; - seminfo.semaem = ns->used_sems; - } else { - seminfo.semusz = SEMUSZ; - seminfo.semaem = SEMAEM; - } - max_id = ipc_get_maxid(&sem_ids(ns)); - up_read(&sem_ids(ns).rw_mutex); - if (copy_to_user (arg.__buf, &seminfo, sizeof(struct seminfo))) - return -EFAULT; - return (max_id < 0) ? 0: max_id; - } - case IPC_STAT: - case SEM_STAT: - { - struct semid64_ds tbuf; - int id; - - 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; - } - - err = -EACCES; - if (ipcperms(ns, &sma->sem_perm, S_IRUGO)) - goto out_unlock; - - err = security_sem_semctl(sma, cmd); - if (err) - goto out_unlock; - - memset(&tbuf, 0, sizeof(tbuf)); - - 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; - } -out_unlock: - sem_unlock(sma); - return err; -} - -static int semctl_main(struct ipc_namespace *ns, int semid, int semnum, - int cmd, int version, union semun arg) -{ - struct sem_array *sma; - struct sem* curr; - int err; - ushort fast_sem_io[SEMMSL_FAST]; - ushort* sem_io = fast_sem_io; - int nsems; - struct list_head tasks; - - sma = sem_lock_check(ns, semid); - if (IS_ERR(sma)) - return PTR_ERR(sma); - - INIT_LIST_HEAD(&tasks); - nsems = sma->sem_nsems; - - err = -EACCES; - if (ipcperms(ns, &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) { - sem_getref_and_unlock(sma); - - sem_io = ipc_alloc(sizeof(ushort)*nsems); - if(sem_io == NULL) { - sem_putref(sma); - return -ENOMEM; - } - - sem_lock_and_putref(sma); - 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; - - sem_getref_and_unlock(sma); - - if(nsems > SEMMSL_FAST) { - sem_io = ipc_alloc(sizeof(ushort)*nsems); - if(sem_io == NULL) { - sem_putref(sma); - return -ENOMEM; - } - } - - if (copy_from_user (sem_io, arg.array, nsems*sizeof(ushort))) { - sem_putref(sma); - err = -EFAULT; - goto out_free; - } - - for (i = 0; i < nsems; i++) { - if (sem_io[i] > SEMVMX) { - sem_putref(sma); - err = -ERANGE; - goto out_free; - } - } - sem_lock_and_putref(sma); - 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]; - - assert_spin_locked(&sma->sem_perm.lock); - list_for_each_entry(un, &sma->list_id, list_id) { - for (i = 0; i < nsems; i++) - un->semadj[i] = 0; - } - sma->sem_ctime = get_seconds(); - /* maybe some queued-up processes were waiting for this */ - do_smart_update(sma, NULL, 0, 0, &tasks); - err = 0; - goto out_unlock; - } - /* 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; - - err = -ERANGE; - if (val > SEMVMX || val < 0) - goto out_unlock; - - assert_spin_locked(&sma->sem_perm.lock); - list_for_each_entry(un, &sma->list_id, list_id) - un->semadj[semnum] = 0; - - curr->semval = val; - curr->sempid = task_tgid_vnr(current); - sma->sem_ctime = get_seconds(); - /* maybe some queued-up processes were waiting for this */ - do_smart_update(sma, NULL, 0, 0, &tasks); - err = 0; - goto out_unlock; - } - } -out_unlock: - sem_unlock(sma); - wake_up_sem_queue_do(&tasks); - -out_free: - if(sem_io != fast_sem_io) - ipc_free(sem_io, sizeof(ushort)*nsems); - return err; -} - -static inline unsigned long -copy_semid_from_user(struct semid64_ds *out, void __user *buf, int version) -{ - switch(version) { - case IPC_64: - if (copy_from_user(out, buf, sizeof(*out))) - return -EFAULT; - return 0; - case IPC_OLD: - { - struct semid_ds tbuf_old; - - if(copy_from_user(&tbuf_old, buf, sizeof(tbuf_old))) - return -EFAULT; - - 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; - - return 0; - } - default: - return -EINVAL; - } -} - -/* - * 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. - */ -static int semctl_down(struct ipc_namespace *ns, int semid, - int cmd, int version, union semun arg) -{ - struct sem_array *sma; - int err; - struct semid64_ds semid64; - struct kern_ipc_perm *ipcp; - - if(cmd == IPC_SET) { - if (copy_semid_from_user(&semid64, arg.buf, version)) - return -EFAULT; - } - - ipcp = ipcctl_pre_down(ns, &sem_ids(ns), semid, cmd, - &semid64.sem_perm, 0); - if (IS_ERR(ipcp)) - return PTR_ERR(ipcp); - - sma = container_of(ipcp, struct sem_array, sem_perm); - - err = security_sem_semctl(sma, cmd); - if (err) - goto out_unlock; - - switch(cmd){ - case IPC_RMID: - freeary(ns, ipcp); - goto out_up; - case IPC_SET: - ipc_update_perm(&semid64.sem_perm, ipcp); - sma->sem_ctime = get_seconds(); - break; - default: - err = -EINVAL; - } - -out_unlock: - sem_unlock(sma); -out_up: - up_write(&sem_ids(ns).rw_mutex); - return err; -} - -SYSCALL_DEFINE(semctl)(int semid, int semnum, int cmd, union semun arg) -{ - int err = -EINVAL; - int version; - struct ipc_namespace *ns; - - if (semid < 0) - return -EINVAL; - - version = ipc_parse_version(&cmd); - ns = current->nsproxy->ipc_ns; - - switch(cmd) { - case IPC_INFO: - case SEM_INFO: - case IPC_STAT: - case SEM_STAT: - err = semctl_nolock(ns, semid, cmd, version, arg); - return err; - case GETALL: - case GETVAL: - case GETPID: - case GETNCNT: - case GETZCNT: - case SETVAL: - case SETALL: - err = semctl_main(ns,semid,semnum,cmd,version,arg); - return err; - case IPC_RMID: - case IPC_SET: - err = semctl_down(ns, semid, cmd, version, arg); - return err; - default: - return -EINVAL; - } -} -#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS -asmlinkage long SyS_semctl(int semid, int semnum, int cmd, union semun arg) -{ - return SYSC_semctl((int) semid, (int) semnum, (int) cmd, arg); -} -SYSCALL_ALIAS(sys_semctl, SyS_semctl); -#endif - -/* 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; - - undo_list = current->sysvsem.undo_list; - if (!undo_list) { - undo_list = kzalloc(sizeof(*undo_list), GFP_KERNEL); - if (undo_list == NULL) - return -ENOMEM; - spin_lock_init(&undo_list->lock); - atomic_set(&undo_list->refcnt, 1); - INIT_LIST_HEAD(&undo_list->list_proc); - - 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) -{ - struct sem_undo *un; - - list_for_each_entry_rcu(un, &ulp->list_proc, list_proc) { - if (un->semid == semid) - return un; - } - return NULL; -} - -static struct sem_undo *lookup_undo(struct sem_undo_list *ulp, int semid) -{ - struct sem_undo *un; - - assert_spin_locked(&ulp->lock); - - un = __lookup_undo(ulp, semid); - if (un) { - list_del_rcu(&un->list_proc); - list_add_rcu(&un->list_proc, &ulp->list_proc); - } - return un; -} - -/** - * 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. - * Lifetime-rules: sem_undo is rcu-protected, on success, the function - * performs a rcu_read_lock(). - */ -static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid) -{ - 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); - - rcu_read_lock(); - spin_lock(&ulp->lock); - un = lookup_undo(ulp, semid); - spin_unlock(&ulp->lock); - if (likely(un!=NULL)) - goto out; - rcu_read_unlock(); - - /* no undo structure around - allocate one. */ - /* step 1: figure out the size of the semaphore array */ - sma = sem_lock_check(ns, semid); - if (IS_ERR(sma)) - return ERR_CAST(sma); - - nsems = sma->sem_nsems; - sem_getref_and_unlock(sma); - - /* step 2: allocate new undo structure */ - new = kzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems, GFP_KERNEL); - if (!new) { - sem_putref(sma); - return ERR_PTR(-ENOMEM); - } - - /* step 3: Acquire the lock on semaphore array */ - sem_lock_and_putref(sma); - if (sma->sem_perm.deleted) { - sem_unlock(sma); - kfree(new); - un = ERR_PTR(-EIDRM); - goto out; - } - 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; - } - /* step 5: initialize & link new undo structure */ - new->semadj = (short *) &new[1]; - new->ulp = ulp; - new->semid = semid; - assert_spin_locked(&ulp->lock); - list_add_rcu(&new->list_proc, &ulp->list_proc); - assert_spin_locked(&sma->sem_perm.lock); - list_add(&new->list_id, &sma->list_id); - un = new; - -success: - spin_unlock(&ulp->lock); - rcu_read_lock(); - sem_unlock(sma); -out: - return un; -} - - -/** - * get_queue_result - Retrieve the result code from sem_queue - * @q: Pointer to queue structure - * - * Retrieve the return code from the pending queue. If IN_WAKEUP is found in - * q->status, then we must loop until the value is replaced with the final - * value: This may happen if a task is woken up by an unrelated event (e.g. - * signal) and in parallel the task is woken up by another task because it got - * the requested semaphores. - * - * The function can be called with or without holding the semaphore spinlock. - */ -static int get_queue_result(struct sem_queue *q) -{ - int error; - - error = q->status; - while (unlikely(error == IN_WAKEUP)) { - cpu_relax(); - error = q->status; - } - - return error; -} - - -SYSCALL_DEFINE4(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; - int undos = 0, alter = 0, max; - struct sem_queue queue; - unsigned long jiffies_left = 0; - struct ipc_namespace *ns; - struct list_head tasks; - - ns = current->nsproxy->ipc_ns; - - if (nsops < 1 || semid < 0) - return -EINVAL; - if (nsops > ns->sc_semopm) - 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) - undos = 1; - if (sop->sem_op != 0) - alter = 1; - } - - if (undos) { - un = find_alloc_undo(ns, semid); - if (IS_ERR(un)) { - error = PTR_ERR(un); - goto out_free; - } - } else - un = NULL; - - INIT_LIST_HEAD(&tasks); - - sma = sem_lock_check(ns, semid); - if (IS_ERR(sma)) { - if (un) - rcu_read_unlock(); - error = PTR_ERR(sma); - goto out_free; - } - - /* - * semid identifiers are not unique - find_alloc_undo may have - * allocated an undo structure, it was invalidated by an RMID - * and now a new array with received the same id. Check and fail. - * This case can be detected checking un->semid. The existence of - * "un" itself is guaranteed by rcu. - */ - error = -EIDRM; - 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(); - } - } - - error = -EFBIG; - if (max >= sma->sem_nsems) - goto out_unlock_free; - - error = -EACCES; - if (ipcperms(ns, &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; - - error = try_atomic_semop (sma, sops, nsops, un, task_tgid_vnr(current)); - if (error <= 0) { - if (alter && error == 0) - do_smart_update(sma, sops, nsops, 1, &tasks); - - 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. - */ - - queue.sops = sops; - queue.nsops = nsops; - queue.undo = un; - queue.pid = task_tgid_vnr(current); - queue.alter = alter; - if (alter) - list_add_tail(&queue.list, &sma->sem_pending); - else - list_add(&queue.list, &sma->sem_pending); - - if (nsops == 1) { - struct sem *curr; - curr = &sma->sem_base[sops->sem_num]; - - if (alter) - list_add_tail(&queue.simple_list, &curr->sem_pending); - else - list_add(&queue.simple_list, &curr->sem_pending); - } else { - INIT_LIST_HEAD(&queue.simple_list); - sma->complex_count++; - } - - queue.status = -EINTR; - queue.sleeper = current; - -sleep_again: - current->state = TASK_INTERRUPTIBLE; - sem_unlock(sma); - - if (timeout) - jiffies_left = schedule_timeout(jiffies_left); - else - schedule(); - - error = get_queue_result(&queue); - - if (error != -EINTR) { - /* fast path: update_queue already obtained all requested - * resources. - * Perform a smp_mb(): User space could assume that semop() - * is a memory barrier: Without the mb(), the cpu could - * speculatively read in user space stale data that was - * overwritten by the previous owner of the semaphore. - */ - smp_mb(); - - goto out_free; - } - - sma = sem_lock(ns, semid); - - /* - * Wait until it's guaranteed that no wakeup_sem_queue_do() is ongoing. - */ - error = get_queue_result(&queue); - - /* - * Array removed? If yes, leave without sem_unlock(). - */ - if (IS_ERR(sma)) { - goto out_free; - } - - - /* - * If queue.status != -EINTR we are woken up by another process. - * Leave without unlink_queue(), but with sem_unlock(). - */ - - 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; - - /* - * If the wakeup was spurious, just retry - */ - if (error == -EINTR && !signal_pending(current)) - goto sleep_again; - - unlink_queue(sma, &queue); - -out_unlock_free: - sem_unlock(sma); - - wake_up_sem_queue_do(&tasks); -out_free: - if(sops != fast_sops) - kfree(sops); - return error; -} - -SYSCALL_DEFINE3(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. - */ - -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; - 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) -{ - struct sem_undo_list *ulp; - - ulp = tsk->sysvsem.undo_list; - if (!ulp) - return; - tsk->sysvsem.undo_list = NULL; - - if (!atomic_dec_and_test(&ulp->refcnt)) - return; - - for (;;) { - struct sem_array *sma; - struct sem_undo *un; - struct list_head tasks; - int semid; - int i; - - rcu_read_lock(); - un = list_entry_rcu(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(); - - if (semid == -1) - break; - - sma = sem_lock_check(tsk->nsproxy->ipc_ns, un->semid); - - /* exit_sem raced with IPC_RMID, nothing to do */ - if (IS_ERR(sma)) - continue; - - 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 */ - assert_spin_locked(&sma->sem_perm.lock); - list_del(&un->list_id); - - spin_lock(&ulp->lock); - list_del_rcu(&un->list_proc); - spin_unlock(&ulp->lock); - - /* perform adjustments registered in un */ - for (i = 0; i < sma->sem_nsems; i++) { - struct sem * semaphore = &sma->sem_base[i]; - if (un->semadj[i]) { - semaphore->semval += un->semadj[i]; - /* - * 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> - */ - if (semaphore->semval < 0) - semaphore->semval = 0; - if (semaphore->semval > SEMVMX) - semaphore->semval = SEMVMX; - semaphore->sempid = task_tgid_vnr(current); - } - } - /* maybe some queued-up processes were waiting for this */ - INIT_LIST_HEAD(&tasks); - do_smart_update(sma, NULL, 0, 1, &tasks); - sem_unlock(sma); - wake_up_sem_queue_do(&tasks); - - kfree_rcu(un, rcu); - } - kfree(ulp); -} - -#ifdef CONFIG_PROC_FS -static int sysvipc_sem_proc_show(struct seq_file *s, void *it) -{ - struct sem_array *sma = it; - - return seq_printf(s, - "%10d %10d %4o %10u %5u %5u %5u %5u %10lu %10lu\n", - sma->sem_perm.key, - sma->sem_perm.id, - 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); -} -#endif |