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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>
This commit is contained in:
Manfred Spraul 2013-09-30 13:45:07 -07:00 committed by Greg Kroah-Hartman
parent 901f6fedc5
commit 83aeb6e344
1 changed files with 8 additions and 0 deletions
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8
ipc/sem.c
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@ -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,