path: root/ipc/sem.c
diff options
authorManfred Spraul <manfred@colorfullife.com>2013-09-30 13:45:07 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-09-30 14:31:01 -0700
commitd8c633766ad88527f25d9f81a5c2f083d78a2b39 (patch)
tree68d0ce69d04d245b8c4236b84892ea740232d6f2 /ipc/sem.c
parent6d07b68ce16ae9535955ba2059dedba5309c3ca1 (diff)
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/sem.c')
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,

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