diff options
Diffstat (limited to 'ipc/sem.c')
| -rw-r--r-- | ipc/sem.c | 24 |
1 files changed, 13 insertions, 11 deletions
diff --git a/ipc/sem.c b/ipc/sem.c index db9d241af133..cc9ac35b793c 100644 --- a/ipc/sem.c +++ b/ipc/sem.c @@ -584,10 +584,11 @@ 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 * @@ -595,7 +596,6 @@ 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) { @@ -607,7 +607,7 @@ static int perform_atomic_semop(struct sem_array *sma, struct sembuf *sops, curr = sma->sem_base + sop->sem_num; sem_op = sop->sem_op; result = curr->semval; - + if (!sem_op && result) goto would_block; @@ -616,25 +616,24 @@ 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 +649,10 @@ 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--; } |