Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756159Ab3IYPZH (ORCPT ); Wed, 25 Sep 2013 11:25:07 -0400 Received: from mail-bk0-f45.google.com ([209.85.214.45]:54121 "EHLO mail-bk0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755549Ab3IYPZF (ORCPT ); Wed, 25 Sep 2013 11:25:05 -0400 From: Manfred Spraul To: Andrew Morton Cc: LKML , Davidlohr Bueso , Mike Galbraith , Manfred Spraul Subject: [PATCH] ipc/sem.c: Synchronize the proc interface Date: Wed, 25 Sep 2013 17:24:49 +0200 Message-Id: <1380122689-6789-1-git-send-email-manfred@colorfullife.com> X-Mailer: git-send-email 1.8.3.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1428 Lines: 45 The proc interface is not aware of sem_lock(), it 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. Andrew: - Could you include the patch in -mm and push it towards Linus? - The patch depends on ipc-semc-fix-race-in-sem_lock.patch Signed-off-by: Manfred Spraul --- ipc/sem.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/ipc/sem.c b/ipc/sem.c index 4a92c04..e5d9bb8 100644 --- a/ipc/sem.c +++ b/ipc/sem.c @@ -2095,6 +2095,14 @@ 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, -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/