X-Git-Url: http://pileus.org/git/?a=blobdiff_plain;ds=sidebyside;f=ipc%2Fsem.c;h=bee5554173120780374e6b42228d13c786ceb315;hb=03c7287dd22c18815964219c9a2e75054cd004df;hp=db9d241af133d770cb0a95a22cacf257f79b1215;hpb=c2ac2ae44d4c32382d001672021116e771bef4c9;p=~andy%2Flinux diff --git a/ipc/sem.c b/ipc/sem.c index db9d241af13..bee55541731 100644 --- a/ipc/sem.c +++ b/ipc/sem.c @@ -188,7 +188,7 @@ void sem_exit_ns(struct ipc_namespace *ns) } #endif -void __init sem_init (void) +void __init sem_init(void) { sem_init_ns(&init_ipc_ns); ipc_init_proc_interface("sysvipc/sem", @@ -225,7 +225,7 @@ static void unmerge_queues(struct sem_array *sma) } /** - * merge_queues - Merge single semop queues into global queue + * merge_queues - merge single semop queues into global queue * @sma: semaphore array * * This function merges all per-semaphore queues into the global queue. @@ -394,7 +394,7 @@ static inline struct sem_array *sem_obtain_lock(struct ipc_namespace *ns, /* ipc_rmid() may have already freed the ID while sem_lock * was spinning: verify that the structure is still valid */ - if (!ipcp->deleted) + if (ipc_valid_object(ipcp)) return container_of(ipcp, struct sem_array, sem_perm); sem_unlock(sma, *locknum); @@ -445,11 +445,11 @@ static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s) * * 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. + * * 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: @@ -474,7 +474,6 @@ static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s) * * Called with sem_ids.rwsem held (as a writer) */ - static int newary(struct ipc_namespace *ns, struct ipc_params *params) { int id; @@ -491,12 +490,12 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params) if (ns->used_sems + nsems > ns->sc_semmns) return -ENOSPC; - size = sizeof (*sma) + nsems * sizeof (struct sem); + size = sizeof(*sma) + nsems * sizeof(struct sem); sma = ipc_rcu_alloc(size); - if (!sma) { + if (!sma) return -ENOMEM; - } - memset (sma, 0, size); + + memset(sma, 0, size); sma->sem_perm.mode = (semflg & S_IRWXUGO); sma->sem_perm.key = key; @@ -584,10 +583,11 @@ SYSCALL_DEFINE3(semget, key_t, key, int, nsems, int, semflg) return ipcget(ns, &sem_ids(ns), &sem_ops, &sem_params); } -/** perform_atomic_semop - Perform (if possible) a semaphore operation +/** + * perform_atomic_semop - Perform (if possible) a semaphore operation * @sma: semaphore array * @sops: array with operations that should be checked - * @nsems: number of sops + * @nsops: number of operations * @un: undo array * @pid: pid that did the change * @@ -595,19 +595,18 @@ SYSCALL_DEFINE3(semget, key_t, key, int, nsems, int, semflg) * Returns 1 if the operation is impossible, the caller must sleep. * Negative values are error codes. */ - static int perform_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; + 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; @@ -616,25 +615,24 @@ static int perform_atomic_semop(struct sem_array *sma, struct sembuf *sops, 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. - */ + /* Exceeding the undo range is an error. */ if (undo < (-SEMAEM - 1) || undo > SEMAEM) goto out_of_range; + un->semadj[sop->sem_num] = undo; } + 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: @@ -650,7 +648,10 @@ would_block: undo: sop--; while (sop >= sops) { - sma->sem_base[sop->sem_num].semval -= sop->sem_op; + sem_op = sop->sem_op; + sma->sem_base[sop->sem_num].semval -= sem_op; + if (sop->sem_flg & SEM_UNDO) + un->semadj[sop->sem_num] += sem_op; sop--; } @@ -680,7 +681,7 @@ static void wake_up_sem_queue_prepare(struct list_head *pt, } /** - * wake_up_sem_queue_do(pt) - do the actual wake-up + * wake_up_sem_queue_do - do the actual wake-up * @pt: list of tasks to be woken up * * Do the actual wake-up. @@ -746,7 +747,7 @@ static int check_restart(struct sem_array *sma, struct sem_queue *q) } /** - * wake_const_ops(sma, semnum, pt) - Wake up non-alter tasks + * wake_const_ops - wake up non-alter tasks * @sma: semaphore array. * @semnum: semaphore that was modified. * @pt: list head for the tasks that must be woken up. @@ -796,15 +797,14 @@ static int wake_const_ops(struct sem_array *sma, int semnum, } /** - * do_smart_wakeup_zero(sma, sops, nsops, pt) - wakeup all wait for zero tasks + * do_smart_wakeup_zero - wakeup all wait for zero tasks * @sma: semaphore array * @sops: operations that were performed * @nsops: number of operations * @pt: list head of the tasks that must be woken up. * - * do_smart_wakeup_zero() checks all required queue for wait-for-zero - * operations, based on the actual changes that were performed on the - * semaphore array. + * Checks all required queue for wait-for-zero operations, based + * on the actual changes that were performed on the semaphore array. * The function returns 1 if at least one operation was completed successfully. */ static int do_smart_wakeup_zero(struct sem_array *sma, struct sembuf *sops, @@ -848,7 +848,7 @@ static int do_smart_wakeup_zero(struct sem_array *sma, struct sembuf *sops, /** - * update_queue(sma, semnum): Look for tasks that can be completed. + * update_queue - 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. @@ -918,7 +918,7 @@ again: } /** - * set_semotime(sma, sops) - set sem_otime + * set_semotime - set sem_otime * @sma: semaphore array * @sops: operations that modified the array, may be NULL * @@ -936,7 +936,7 @@ static void set_semotime(struct sem_array *sma, struct sembuf *sops) } /** - * do_smart_update(sma, sops, nsops, otime, pt) - optimized update_queue + * do_smart_update - optimized update_queue * @sma: semaphore array * @sops: operations that were performed * @nsops: number of operations @@ -998,21 +998,21 @@ static void do_smart_update(struct sem_array *sma, struct sembuf *sops, int nsop * 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) +static int count_semncnt(struct sem_array *sma, ushort semnum) { int semncnt; - struct sem_queue * q; + struct sem_queue *q; semncnt = 0; list_for_each_entry(q, &sma->sem_base[semnum].pending_alter, list) { - struct sembuf * sops = q->sops; + struct sembuf *sops = q->sops; BUG_ON(sops->sem_num != semnum); if ((sops->sem_op < 0) && !(sops->sem_flg & IPC_NOWAIT)) semncnt++; } list_for_each_entry(q, &sma->pending_alter, list) { - struct sembuf * sops = q->sops; + struct sembuf *sops = q->sops; int nsops = q->nsops; int i; for (i = 0; i < nsops; i++) @@ -1024,21 +1024,21 @@ static int count_semncnt (struct sem_array * sma, ushort semnum) return semncnt; } -static int count_semzcnt (struct sem_array * sma, ushort semnum) +static int count_semzcnt(struct sem_array *sma, ushort semnum) { int semzcnt; - struct sem_queue * q; + struct sem_queue *q; semzcnt = 0; list_for_each_entry(q, &sma->sem_base[semnum].pending_const, list) { - struct sembuf * sops = q->sops; + struct sembuf *sops = q->sops; BUG_ON(sops->sem_num != semnum); if ((sops->sem_op == 0) && !(sops->sem_flg & IPC_NOWAIT)) semzcnt++; } list_for_each_entry(q, &sma->pending_const, list) { - struct sembuf * sops = q->sops; + struct sembuf *sops = q->sops; int nsops = q->nsops; int i; for (i = 0; i < nsops; i++) @@ -1108,7 +1108,7 @@ static void freeary(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp) static unsigned long copy_semid_to_user(void __user *buf, struct semid64_ds *in, int version) { - switch(version) { + switch (version) { case IPC_64: return copy_to_user(buf, in, sizeof(*in)); case IPC_OLD: @@ -1151,7 +1151,7 @@ static int semctl_nolock(struct ipc_namespace *ns, int semid, int err; struct sem_array *sma; - switch(cmd) { + switch (cmd) { case IPC_INFO: case SEM_INFO: { @@ -1162,7 +1162,7 @@ static int semctl_nolock(struct ipc_namespace *ns, int semid, if (err) return err; - memset(&seminfo,0,sizeof(seminfo)); + memset(&seminfo, 0, sizeof(seminfo)); seminfo.semmni = ns->sc_semmni; seminfo.semmns = ns->sc_semmns; seminfo.semmsl = ns->sc_semmsl; @@ -1183,7 +1183,7 @@ static int semctl_nolock(struct ipc_namespace *ns, int semid, up_read(&sem_ids(ns).rwsem); if (copy_to_user(p, &seminfo, sizeof(struct seminfo))) return -EFAULT; - return (max_id < 0) ? 0: max_id; + return (max_id < 0) ? 0 : max_id; } case IPC_STAT: case SEM_STAT: @@ -1239,7 +1239,7 @@ static int semctl_setval(struct ipc_namespace *ns, int semid, int semnum, { struct sem_undo *un; struct sem_array *sma; - struct sem* curr; + struct sem *curr; int err; struct list_head tasks; int val; @@ -1282,7 +1282,7 @@ static int semctl_setval(struct ipc_namespace *ns, int semid, int semnum, sem_lock(sma, NULL, -1); - if (sma->sem_perm.deleted) { + if (!ipc_valid_object(&sma->sem_perm)) { sem_unlock(sma, -1); rcu_read_unlock(); return -EIDRM; @@ -1309,10 +1309,10 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum, int cmd, void __user *p) { struct sem_array *sma; - struct sem* curr; + struct sem *curr; int err, nsems; ushort fast_sem_io[SEMMSL_FAST]; - ushort* sem_io = fast_sem_io; + ushort *sem_io = fast_sem_io; struct list_head tasks; INIT_LIST_HEAD(&tasks); @@ -1342,11 +1342,11 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum, int i; sem_lock(sma, NULL, -1); - if (sma->sem_perm.deleted) { + if (!ipc_valid_object(&sma->sem_perm)) { err = -EIDRM; goto out_unlock; } - if(nsems > SEMMSL_FAST) { + if (nsems > SEMMSL_FAST) { if (!ipc_rcu_getref(sma)) { err = -EIDRM; goto out_unlock; @@ -1354,14 +1354,14 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum, sem_unlock(sma, -1); rcu_read_unlock(); sem_io = ipc_alloc(sizeof(ushort)*nsems); - if(sem_io == NULL) { + if (sem_io == NULL) { ipc_rcu_putref(sma, ipc_rcu_free); return -ENOMEM; } rcu_read_lock(); sem_lock_and_putref(sma); - if (sma->sem_perm.deleted) { + if (!ipc_valid_object(&sma->sem_perm)) { err = -EIDRM; goto out_unlock; } @@ -1371,7 +1371,7 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum, sem_unlock(sma, -1); rcu_read_unlock(); err = 0; - if(copy_to_user(array, sem_io, nsems*sizeof(ushort))) + if (copy_to_user(array, sem_io, nsems*sizeof(ushort))) err = -EFAULT; goto out_free; } @@ -1386,15 +1386,15 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum, } rcu_read_unlock(); - if(nsems > SEMMSL_FAST) { + if (nsems > SEMMSL_FAST) { sem_io = ipc_alloc(sizeof(ushort)*nsems); - if(sem_io == NULL) { + if (sem_io == NULL) { ipc_rcu_putref(sma, ipc_rcu_free); return -ENOMEM; } } - if (copy_from_user (sem_io, p, nsems*sizeof(ushort))) { + if (copy_from_user(sem_io, p, nsems*sizeof(ushort))) { ipc_rcu_putref(sma, ipc_rcu_free); err = -EFAULT; goto out_free; @@ -1409,7 +1409,7 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum, } rcu_read_lock(); sem_lock_and_putref(sma); - if (sma->sem_perm.deleted) { + if (!ipc_valid_object(&sma->sem_perm)) { err = -EIDRM; goto out_unlock; } @@ -1435,7 +1435,7 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum, goto out_rcu_wakeup; sem_lock(sma, NULL, -1); - if (sma->sem_perm.deleted) { + if (!ipc_valid_object(&sma->sem_perm)) { err = -EIDRM; goto out_unlock; } @@ -1449,10 +1449,10 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum, err = curr->sempid; goto out_unlock; case GETNCNT: - err = count_semncnt(sma,semnum); + err = count_semncnt(sma, semnum); goto out_unlock; case GETZCNT: - err = count_semzcnt(sma,semnum); + err = count_semzcnt(sma, semnum); goto out_unlock; } @@ -1462,7 +1462,7 @@ out_rcu_wakeup: rcu_read_unlock(); wake_up_sem_queue_do(&tasks); out_free: - if(sem_io != fast_sem_io) + if (sem_io != fast_sem_io) ipc_free(sem_io, sizeof(ushort)*nsems); return err; } @@ -1470,7 +1470,7 @@ out_free: static inline unsigned long copy_semid_from_user(struct semid64_ds *out, void __user *buf, int version) { - switch(version) { + switch (version) { case IPC_64: if (copy_from_user(out, buf, sizeof(*out))) return -EFAULT; @@ -1479,7 +1479,7 @@ copy_semid_from_user(struct semid64_ds *out, void __user *buf, int version) { struct semid_ds tbuf_old; - if(copy_from_user(&tbuf_old, buf, sizeof(tbuf_old))) + if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old))) return -EFAULT; out->sem_perm.uid = tbuf_old.sem_perm.uid; @@ -1506,7 +1506,7 @@ static int semctl_down(struct ipc_namespace *ns, int semid, struct semid64_ds semid64; struct kern_ipc_perm *ipcp; - if(cmd == IPC_SET) { + if (cmd == IPC_SET) { if (copy_semid_from_user(&semid64, p, version)) return -EFAULT; } @@ -1566,7 +1566,7 @@ SYSCALL_DEFINE4(semctl, int, semid, int, semnum, int, cmd, unsigned long, arg) version = ipc_parse_version(&cmd); ns = current->nsproxy->ipc_ns; - switch(cmd) { + switch (cmd) { case IPC_INFO: case SEM_INFO: case IPC_STAT: @@ -1634,7 +1634,7 @@ static struct sem_undo *lookup_undo(struct sem_undo_list *ulp, int semid) { struct sem_undo *un; - assert_spin_locked(&ulp->lock); + assert_spin_locked(&ulp->lock); un = __lookup_undo(ulp, semid); if (un) { @@ -1645,7 +1645,7 @@ static struct sem_undo *lookup_undo(struct sem_undo_list *ulp, int semid) } /** - * find_alloc_undo - Lookup (and if not present create) undo array + * find_alloc_undo - lookup (and if not present create) undo array * @ns: namespace * @semid: semaphore array id * @@ -1670,7 +1670,7 @@ static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid) spin_lock(&ulp->lock); un = lookup_undo(ulp, semid); spin_unlock(&ulp->lock); - if (likely(un!=NULL)) + if (likely(un != NULL)) goto out; /* no undo structure around - allocate one. */ @@ -1699,7 +1699,7 @@ static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid) /* step 3: Acquire the lock on semaphore array */ rcu_read_lock(); sem_lock_and_putref(sma); - if (sma->sem_perm.deleted) { + if (!ipc_valid_object(&sma->sem_perm)) { sem_unlock(sma, -1); rcu_read_unlock(); kfree(new); @@ -1735,7 +1735,7 @@ out: /** - * get_queue_result - Retrieve the result code from sem_queue + * 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 @@ -1765,7 +1765,7 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops, int error = -EINVAL; struct sem_array *sma; struct sembuf fast_sops[SEMOPM_FAST]; - struct sembuf* sops = fast_sops, *sop; + struct sembuf *sops = fast_sops, *sop; struct sem_undo *un; int undos = 0, alter = 0, max, locknum; struct sem_queue queue; @@ -1779,13 +1779,13 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops, return -EINVAL; if (nsops > ns->sc_semopm) return -E2BIG; - if(nsops > SEMOPM_FAST) { - sops = kmalloc(sizeof(*sops)*nsops,GFP_KERNEL); - if(sops==NULL) + 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; + if (copy_from_user(sops, tsops, nsops * sizeof(*tsops))) { + error = -EFAULT; goto out_free; } if (timeout) { @@ -1846,7 +1846,15 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops, error = -EIDRM; locknum = sem_lock(sma, sops, nsops); - if (sma->sem_perm.deleted) + /* + * We eventually might perform the following check in a lockless + * fashion, considering ipc_valid_object() locking constraints. + * If nsops == 1 and there is no contention for sem_perm.lock, then + * only a per-semaphore lock is held and it's OK to proceed with the + * check below. More details on the fine grained locking scheme + * entangled here and why it's RMID race safe on comments at sem_lock() + */ + if (!ipc_valid_object(&sma->sem_perm)) goto out_unlock_free; /* * semid identifiers are not unique - find_alloc_undo may have @@ -1959,10 +1967,8 @@ sleep_again: * If queue.status != -EINTR we are woken up by another process. * Leave without unlink_queue(), but with sem_unlock(). */ - - if (error != -EINTR) { + if (error != -EINTR) goto out_unlock_free; - } /* * If an interrupt occurred we have to clean up the queue @@ -1984,7 +1990,7 @@ out_rcu_wakeup: rcu_read_unlock(); wake_up_sem_queue_do(&tasks); out_free: - if(sops != fast_sops) + if (sops != fast_sops) kfree(sops); return error; } @@ -2068,7 +2074,7 @@ void exit_sem(struct task_struct *tsk) sem_lock(sma, NULL, -1); /* exit_sem raced with IPC_RMID, nothing to do */ - if (sma->sem_perm.deleted) { + if (!ipc_valid_object(&sma->sem_perm)) { sem_unlock(sma, -1); rcu_read_unlock(); continue; @@ -2093,7 +2099,7 @@ void exit_sem(struct task_struct *tsk) /* perform adjustments registered in un */ for (i = 0; i < sma->sem_nsems; i++) { - struct sem * semaphore = &sma->sem_base[i]; + struct sem *semaphore = &sma->sem_base[i]; if (un->semadj[i]) { semaphore->semval += un->semadj[i]; /* @@ -2107,7 +2113,7 @@ void exit_sem(struct task_struct *tsk) * Linux caps the semaphore value, both at 0 * and at SEMVMX. * - * Manfred + * Manfred */ if (semaphore->semval < 0) semaphore->semval = 0;