From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2F2F2C71122 for ; Sun, 14 Oct 2018 15:34:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E5DB320835 for ; Sun, 14 Oct 2018 15:34:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E5DB320835 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=decadent.org.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728485AbeJNXQN (ORCPT ); Sun, 14 Oct 2018 19:16:13 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:36600 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727809AbeJNXQN (ORCPT ); Sun, 14 Oct 2018 19:16:13 -0400 Received: from [2a02:8011:400e:2:cbab:f00:c93f:614] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.84_2) (envelope-from ) id 1gBiMC-0004cd-26; Sun, 14 Oct 2018 16:31:04 +0100 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1gBiLP-0000EF-K8; Sun, 14 Oct 2018 16:30:15 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Linus Torvalds" , "PrasannaKumar Muralidharan" , "Davidlohr Bueso" , "Philip Semanchuk" , "Herton R. Krzesinski" , "Manfred Spraul" , "Michael Kerrisk" , "Davidlohr Bueso" Date: Sun, 14 Oct 2018 16:25:41 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 070/366] ipc/sem: make semctl setting sempid consistent In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:cbab:f00:c93f:614 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.60-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Davidlohr Bueso commit a5f4db877177d2a3d7ae62a7bac3a5a27e083d7f upstream. As indicated by bug#112271, Linux sets the sempid value upon semctl, and not only for semop calls. However, within semctl we only do this for SETVAL, leaving SETALL without updating the field, and therefore rather inconsistent behavior when compared to other Unices. There is really no documentation regarding this and therefore users should not make assumptions. With this patch, along with updating semctl.2 manpages, this scenario should become less ambiguous As such, set sempid on SETALL cmd. Also update some in-code documentation, specifying where the sempid is set. Passes ltp and custom testcase where a child (fork) does SETALL to the set. Signed-off-by: Davidlohr Bueso Reported-by: Philip Semanchuk Cc: Michael Kerrisk Cc: PrasannaKumar Muralidharan Cc: Manfred Spraul Cc: Herton R. Krzesinski Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings --- ipc/sem.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) --- a/ipc/sem.c +++ b/ipc/sem.c @@ -92,7 +92,14 @@ /* One semaphore structure for each semaphore in the system. */ struct sem { int semval; /* current value */ - int sempid; /* pid of last operation */ + /* + * PID of the process that last modified the semaphore. For + * Linux, specifically these are: + * - semop + * - semctl, via SETVAL and SETALL. + * - at task exit when performing undo adjustments (see exit_sem). + */ + int sempid; spinlock_t lock; /* spinlock for fine-grained semtimedop */ struct list_head pending_alter; /* pending single-sop operations */ /* that alter the semaphore */ @@ -1469,8 +1476,10 @@ static int semctl_main(struct ipc_namesp goto out_unlock; } - for (i = 0; i < nsems; i++) + for (i = 0; i < nsems; i++) { sma->sem_base[i].semval = sem_io[i]; + sma->sem_base[i].sempid = task_tgid_vnr(current); + } ipc_assert_locked_object(&sma->sem_perm); list_for_each_entry(un, &sma->list_id, list_id) {