diff options
| author | Manfred Spraul <manfred@colorfullife.com> | 2013-09-30 13:45:07 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-10-18 07:45:48 -0700 |
| commit | 83aeb6e3449cc54fa8867a0c9cc1b8d2484fa91e (patch) | |
| tree | 53d11e8e80b04f5e644cf202d3387aa314620ddf | |
| parent | 901f6fedc5340d66e2ca67c70dfee926cb5a1ea0 (diff) | |
ipc/sem.c: synchronize the proc interface
commit d8c633766ad88527f25d9f81a5c2f083d78a2b39 upstream.
The proc interface is not aware of sem_lock(), it instead calls
ipc_lock_object() directly. This means that simple semop() operations
can run in parallel with the proc interface. Right now, this is
uncritical, because the implementation doesn't do anything that requires
a proper synchronization.
But it is dangerous and therefore should be fixed.
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | ipc/sem.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/ipc/sem.c b/ipc/sem.c index e20658d76bb..cd6a733011a 100644 --- a/ipc/sem.c +++ b/ipc/sem.c @@ -2103,6 +2103,14 @@ static int sysvipc_sem_proc_show(struct seq_file *s, void *it) struct sem_array *sma = it; time_t sem_otime; + /* + * The proc interface isn't aware of sem_lock(), it calls + * ipc_lock_object() directly (in sysvipc_find_ipc). + * In order to stay compatible with sem_lock(), we must wait until + * all simple semop() calls have left their critical regions. + */ + sem_wait_array(sma); + sem_otime = get_semotime(sma); return seq_printf(s, |