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-rw-r--r--ipc/sem.c26
1 files changed, 20 insertions, 6 deletions
diff --git a/ipc/sem.c b/ipc/sem.c
index 2f2a4795957..cb0070ecf5b 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -962,17 +962,31 @@ static inline int get_undo_list(struct sem_undo_list **undo_listp)
return 0;
}
-static struct sem_undo *lookup_undo(struct sem_undo_list *ulp, int semid)
+static struct sem_undo *__lookup_undo(struct sem_undo_list *ulp, int semid)
{
- struct sem_undo *walk;
+ struct sem_undo *un;
- list_for_each_entry_rcu(walk, &ulp->list_proc, list_proc) {
- if (walk->semid == semid)
- return walk;
+ 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
@@ -1308,7 +1322,7 @@ void exit_sem(struct task_struct *tsk)
if (IS_ERR(sma))
continue;
- un = lookup_undo(ulp, semid);
+ un = __lookup_undo(ulp, semid);
if (un == NULL) {
/* exit_sem raced with IPC_RMID+semget() that created
* exactly the same semid. Nothing to do.