Commit d8c63376 authored Sep 30, 2013 by Manfred Spraul Committed by Linus Torvalds Sep 30, 2013

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>

parent 6d07b68c

ipc/sem.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -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,