Commit d8c63376 authored by Manfred Spraul's avatar Manfred Spraul Committed by Linus Torvalds

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: default avatarManfred Spraul <>
Cc: Davidlohr Bueso <>
Cc: Mike Galbraith <>
Cc: Rik van Riel <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 6d07b68c
......@@ -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_otime = get_semotime(sma);
return seq_printf(s,
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