diff options
Diffstat (limited to 'ipc/sem.c')
| -rw-r--r-- | ipc/sem.c | 46 |
1 files changed, 6 insertions, 40 deletions
diff --git a/ipc/sem.c b/ipc/sem.c index 40ab34d832a..7617f4f34ed 100644 --- a/ipc/sem.c +++ b/ipc/sem.c @@ -999,36 +999,6 @@ asmlinkage long sys_semctl (int semid, int semnum, int cmd, union semun arg) } } -static inline void lock_semundo(void) -{ - struct sem_undo_list *undo_list; - - undo_list = current->sysvsem.undo_list; - if (undo_list) - spin_lock(&undo_list->lock); -} - -/* This code has an interaction with copy_semundo(). - * Consider; two tasks are sharing the undo_list. task1 - * acquires the undo_list lock in lock_semundo(). If task2 now - * exits before task1 releases the lock (by calling - * unlock_semundo()), then task1 will never call spin_unlock(). - * This leave the sem_undo_list in a locked state. If task1 now creats task3 - * and once again shares the sem_undo_list, the sem_undo_list will still be - * locked, and future SEM_UNDO operations will deadlock. This case is - * dealt with in copy_semundo() by having it reinitialize the spin lock when - * the refcnt goes from 1 to 2. - */ -static inline void unlock_semundo(void) -{ - struct sem_undo_list *undo_list; - - undo_list = current->sysvsem.undo_list; - if (undo_list) - spin_unlock(&undo_list->lock); -} - - /* 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 @@ -1089,9 +1059,9 @@ static struct sem_undo *find_undo(struct ipc_namespace *ns, int semid) if (error) return ERR_PTR(error); - lock_semundo(); + spin_lock(&ulp->lock); un = lookup_undo(ulp, semid); - unlock_semundo(); + spin_unlock(&ulp->lock); if (likely(un!=NULL)) goto out; @@ -1114,10 +1084,10 @@ static struct sem_undo *find_undo(struct ipc_namespace *ns, int semid) new->semadj = (short *) &new[1]; new->semid = semid; - lock_semundo(); + spin_lock(&ulp->lock); un = lookup_undo(ulp, semid); if (un) { - unlock_semundo(); + spin_unlock(&ulp->lock); kfree(new); ipc_lock_by_ptr(&sma->sem_perm); ipc_rcu_putref(sma); @@ -1128,7 +1098,7 @@ static struct sem_undo *find_undo(struct ipc_namespace *ns, int semid) ipc_rcu_putref(sma); if (sma->sem_perm.deleted) { sem_unlock(sma); - unlock_semundo(); + spin_unlock(&ulp->lock); kfree(new); un = ERR_PTR(-EIDRM); goto out; @@ -1139,7 +1109,7 @@ static struct sem_undo *find_undo(struct ipc_namespace *ns, int semid) sma->undo = new; sem_unlock(sma); un = new; - unlock_semundo(); + spin_unlock(&ulp->lock); out: return un; } @@ -1315,10 +1285,6 @@ asmlinkage long sys_semop (int semid, struct sembuf __user *tsops, unsigned nsop /* If CLONE_SYSVSEM is set, establish sharing of SEM_UNDO state between * parent and child tasks. - * - * See the notes above unlock_semundo() regarding the spin_lock_init() - * in this code. Initialize the undo_list->lock here instead of get_undo_list() - * because of the reasoning in the comment above unlock_semundo. */ int copy_semundo(unsigned long clone_flags, struct task_struct *tsk) |