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| author | Manfred Spraul <manfred@colorfullife.com> | 2013-09-30 13:45:07 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-09-30 14:31:01 -0700 |
| commit | d8c633766ad88527f25d9f81a5c2f083d78a2b39 (patch) | |
| tree | 68d0ce69d04d245b8c4236b84892ea740232d6f2 /ipc | |
| parent | 6d07b68ce16ae9535955ba2059dedba5309c3ca1 (diff) | |
| download | lwn-d8c633766ad88527f25d9f81a5c2f083d78a2b39.tar.gz lwn-d8c633766ad88527f25d9f81a5c2f083d78a2b39.zip | |
ipc/sem.c: synchronize the proc interface
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>
Diffstat (limited to 'ipc')
| -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 e20658d76bb5..cd6a733011a2 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, |