3.11-stable review patch. If anyone has any objections, please let me know.
------------------ From: Manfred Spraul <[email protected]> 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 <[email protected]> Cc: Davidlohr Bueso <[email protected]> Cc: Mike Galbraith <[email protected]> Cc: Rik van Riel <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- ipc/sem.c | 8 ++++++++ 1 file changed, 8 insertions(+) --- a/ipc/sem.c +++ b/ipc/sem.c @@ -2103,6 +2103,14 @@ static int sysvipc_sem_proc_show(struct 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, -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
