From patchwork Mon Aug 22 20:28:48 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Samuel Thibault X-Patchwork-Id: 56926 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id D30623857C70 for ; Mon, 22 Aug 2022 20:29:01 +0000 (GMT) X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from sonata.ens-lyon.org (sonata.ens-lyon.org [140.77.166.138]) by sourceware.org (Postfix) with ESMTPS id B8E2A3858419 for ; Mon, 22 Aug 2022 20:28:49 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org B8E2A3858419 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=ens-lyon.org Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=bounce.ens-lyon.org Received: from localhost (localhost [127.0.0.1]) by sonata.ens-lyon.org (Postfix) with ESMTP id E14922017C; Mon, 22 Aug 2022 22:28:47 +0200 (CEST) Received: from sonata.ens-lyon.org ([127.0.0.1]) by localhost (sonata.ens-lyon.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id cIm8Nu8ERTdI; Mon, 22 Aug 2022 22:28:47 +0200 (CEST) Received: from begin (lfbn-bor-1-376-208.w109-215.abo.wanadoo.fr [109.215.91.208]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by sonata.ens-lyon.org (Postfix) with ESMTPSA id D083D20167; Mon, 22 Aug 2022 22:28:47 +0200 (CEST) Received: from samy by begin with local (Exim 4.96) (envelope-from ) id 1oQE2S-00Fhbm-1d; Mon, 22 Aug 2022 22:28:48 +0200 From: Samuel Thibault To: libc-alpha@sourceware.org Subject: [hurd, commited] htl: Make pthread*_cond_timedwait register wref before releasing mutex Date: Mon, 22 Aug 2022 22:28:48 +0200 Message-Id: <20220822202848.3742543-1-samuel.thibault@ens-lyon.org> X-Mailer: git-send-email 2.35.1 MIME-Version: 1.0 X-Spam-Status: No, score=-13.4 required=5.0 tests=BAYES_00, GIT_PATCH_0, JMQ_SPF_NEUTRAL, KAM_DMARC_STATUS, RCVD_IN_DNSWL_NONE, SPF_HELO_PASS, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: commit-hurd@gnu.org Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" Otherwise another thread could be rightly trying to destroy the condition, see e.g. tst-cond20. --- sysdeps/htl/pt-cond-timedwait.c | 10 ++++++---- sysdeps/mach/hurd/htl/pt-hurd-cond-timedwait.c | 10 ++++++---- 2 files changed, 12 insertions(+), 8 deletions(-) diff --git a/sysdeps/htl/pt-cond-timedwait.c b/sysdeps/htl/pt-cond-timedwait.c index 6f4cb41bf1..4352e54fff 100644 --- a/sysdeps/htl/pt-cond-timedwait.c +++ b/sysdeps/htl/pt-cond-timedwait.c @@ -142,13 +142,15 @@ __pthread_cond_timedwait_internal (pthread_cond_t *cond, __pthread_mutex_unlock (&self->cancel_lock); - /* Release MUTEX before blocking. */ - __pthread_mutex_unlock (mutex); - /* Increase the waiter reference count. Relaxed MO is sufficient because - we only need to synchronize when decrementing the reference count. */ + we only need to synchronize when decrementing the reference count. + We however need to have the mutex held to prevent concurrency with + a pthread_cond_destroy. */ atomic_fetch_add_relaxed (&cond->__wrefs, 2); + /* Release MUTEX before blocking. */ + __pthread_mutex_unlock (mutex); + /* Block the thread. */ if (abstime != NULL) err = __pthread_timedblock (self, abstime, clock_id); diff --git a/sysdeps/mach/hurd/htl/pt-hurd-cond-timedwait.c b/sysdeps/mach/hurd/htl/pt-hurd-cond-timedwait.c index 16f0d3b309..1677925755 100644 --- a/sysdeps/mach/hurd/htl/pt-hurd-cond-timedwait.c +++ b/sysdeps/mach/hurd/htl/pt-hurd-cond-timedwait.c @@ -103,6 +103,12 @@ __pthread_hurd_cond_timedwait_internal (pthread_cond_t *cond, __pthread_spin_unlock (&cond->__lock); __spin_unlock (&ss->lock); + /* Increase the waiter reference count. Relaxed MO is sufficient because + we only need to synchronize when decrementing the reference count. + We however need to have the mutex held to prevent concurrency with + a pthread_cond_destroy. */ + atomic_fetch_add_relaxed (&cond->__wrefs, 2); + if (cancel) { /* Cancelled on entry. Just leave the mutex locked. */ @@ -115,10 +121,6 @@ __pthread_hurd_cond_timedwait_internal (pthread_cond_t *cond, /* Release MUTEX before blocking. */ __pthread_mutex_unlock (mutex); - /* Increase the waiter reference count. Relaxed MO is sufficient because - we only need to synchronize when decrementing the reference count. */ - atomic_fetch_add_relaxed (&cond->__wrefs, 2); - /* Block the thread. */ if (abstime != NULL) err = __pthread_timedblock (self, abstime, clock_id);