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| author | Herton R. Krzesinski <herton@redhat.com> | 2015-08-14 15:35:05 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-08-14 15:56:32 -0700 |
| commit | a97955844807e327df11aa33869009d14d6b7de0 (patch) | |
| tree | 20d83d811aa907898be0b09b6c4c94f8789e7224 /ipc/sem.c | |
| parent | 602b8593d2b4138c10e922eeaafe306f6b51817b (diff) | |
| download | lwn-a97955844807e327df11aa33869009d14d6b7de0.tar.gz lwn-a97955844807e327df11aa33869009d14d6b7de0.zip | |
ipc,sem: remove uneeded sem_undo_list lock usage in exit_sem()
After we acquire the sma->sem_perm lock in exit_sem(), we are protected
against a racing IPC_RMID operation. Also at that point, we are the last
user of sem_undo_list. Therefore it isn't required that we acquire or use
ulp->lock.
Signed-off-by: Herton R. Krzesinski <herton@redhat.com>
Acked-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Rafael Aquini <aquini@redhat.com>
CC: Aristeu Rozanski <aris@redhat.com>
Cc: David Jeffery <djeffery@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'ipc/sem.c')
| -rw-r--r-- | ipc/sem.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/ipc/sem.c b/ipc/sem.c index a37aaeb02561..178f303deea5 100644 --- a/ipc/sem.c +++ b/ipc/sem.c @@ -2123,9 +2123,11 @@ void exit_sem(struct task_struct *tsk) ipc_assert_locked_object(&sma->sem_perm); list_del(&un->list_id); - spin_lock(&ulp->lock); + /* we are the last process using this ulp, acquiring ulp->lock + * isn't required. Besides that, we are also protected against + * IPC_RMID as we hold sma->sem_perm lock now + */ list_del_rcu(&un->list_proc); - spin_unlock(&ulp->lock); /* perform adjustments registered in un */ for (i = 0; i < sma->sem_nsems; i++) { |