From patchwork Thu May 11 20:52:22 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Wakely X-Patchwork-Id: 69182 X-Patchwork-Delegate: trodgers@redhat.com 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 27B983858C54 for ; Thu, 11 May 2023 20:53:06 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 27B983858C54 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1683838386; bh=RKYySIpioQyP+GJvofg3IvS/w/CcC6ndB68/CrthHN4=; h=References:In-Reply-To:Date:Subject:To:Cc:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From:Reply-To:From; b=P4cAIhMpmAAUgCESV6qPItVsIRJDeAXvBWxe47H8RcutJ18iCG7s0ld++HDlQiI3c r0zUs0qG2ftpTsIUNIZ7xgxQbl/BTwDmVzilHZZOYtaR+Iv7UFADJBdHwKzhzFshFe MNk9wMKZmWfW/U0wl3YeRKAnPh+HEOEbVNNRXDBc= X-Original-To: gcc-patches@gcc.gnu.org Delivered-To: gcc-patches@gcc.gnu.org Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by sourceware.org (Postfix) with ESMTPS id 29D843858D1E for ; 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Thu, 11 May 2023 13:52:33 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ4eipcVOFy2ODWdwJ501tlJS2PMJ8PXV7lZBzxVjhsAg6zlbmg/NzUf1JMjFOAaGsbODbosyHbFec5wkPwNKBE= X-Received: by 2002:a2e:9818:0:b0:2a8:c842:d30c with SMTP id a24-20020a2e9818000000b002a8c842d30cmr3952901ljj.44.1683838353312; Thu, 11 May 2023 13:52:33 -0700 (PDT) MIME-Version: 1.0 References: <20230510112009.633444-1-jwakely@redhat.com> In-Reply-To: Date: Thu, 11 May 2023 21:52:22 +0100 Message-ID: Subject: [PATCH v2] libstdc++: Do not use pthread_mutex_clocklock with ThreadSanitizer To: Mike Crowe Cc: "libstdc++" , gcc Patches , Thomas Rodgers X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-Spam-Status: No, score=-12.2 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, HTML_MESSAGE, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2, SPF_HELO_NONE, SPF_NONE, 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-Content-Filtered-By: Mailman/MimeDel 2.1.29 X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Jonathan Wakely via Gcc-patches From: Jonathan Wakely Reply-To: Jonathan Wakely Errors-To: gcc-patches-bounces+patchwork=sourceware.org@gcc.gnu.org Sender: "Gcc-patches" On Thu, 11 May 2023 at 13:42, Jonathan Wakely wrote: > > > On Thu, 11 May 2023 at 13:19, Mike Crowe wrote: > >> However, ... >> >> > > diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4 >> > > index 89e7f5f5f45..e2700b05ec3 100644 >> > > --- a/libstdc++-v3/acinclude.m4 >> > > +++ b/libstdc++-v3/acinclude.m4 >> > > @@ -4284,7 +4284,7 @@ >> AC_DEFUN([GLIBCXX_CHECK_PTHREAD_COND_CLOCKWAIT], [ >> > > [glibcxx_cv_PTHREAD_COND_CLOCKWAIT=no]) >> > > ]) >> > > if test $glibcxx_cv_PTHREAD_COND_CLOCKWAIT = yes; then >> > > - AC_DEFINE(_GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT, 1, [Define if >> > > pthread_cond_clockwait is available in .]) >> > > + AC_DEFINE(_GLIBCXX_USE_PTHREAD_COND_CLOCKWAIT, >> (_GLIBCXX_TSAN==0), >> > > [Define if pthread_cond_clockwait is available in .]) >> > > fi >> >> TSan does appear to have an interceptor for pthread_cond_clockwait, even >> if >> it lacks the others. Does this mean that this part is unnecessary? >> > > Ah good point, thanks. I grepped for clocklock but not clockwait. > In fact it seems like we don't need to change _GLIBCXX_USE_PTHREAD_RWLOCK_CLOCKLOCK either, because I don't get any tsan warnings for that. It doesn't have interceptors for pthread_rwlock_{rd,wr}lock, but it doesn't complain anyway (maybe it's simply not instrumenting the rwlock functions at all?!) So I'm now retesting with this version of the patch, which only touches the USE_PTHREAD_LOCKLOCK macro. Please take another look, thanks. commit 4fc14825c125eece32980df21d09da35e3d5bac6 Author: Jonathan Wakely Date: Tue May 9 09:30:48 2023 libstdc++: Do not use pthread_mutex_clocklock with ThreadSanitizer As noted in https://github.com/llvm/llvm-project/issues/62623 there are no tsan interceptors for some of the new POSIX-1:202x APIs added by https://austingroupbugs.net/view.php?id=1216 so tsan gives false positive warnings for try_lock_for on timed mutexes. Disable the uses of the new pthread_mutex_clocklock API when tsan is active. This changes the semantics of the try_lock_for functions, because it can change which clock is used for the wait. This means those functions might be affected by system clock adjustments when tsan is used, when they would not be affected otherwise. libstdc++-v3/ChangeLog: * acinclude.m4 (GLIBCXX_CHECK_PTHREAD_MUTEX_CLOCKLOCK): Define _GLIBCXX_USE_PTHREAD_MUTEX_CLOCKLOCK in terms of _GLIBCXX_TSAN. * configure: Regenerate. diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4 index 89e7f5f5f45..dce3d16aa5c 100644 --- a/libstdc++-v3/acinclude.m4 +++ b/libstdc++-v3/acinclude.m4 @@ -4314,7 +4314,7 @@ AC_DEFUN([GLIBCXX_CHECK_PTHREAD_MUTEX_CLOCKLOCK], [ [glibcxx_cv_PTHREAD_MUTEX_CLOCKLOCK=no]) ]) if test $glibcxx_cv_PTHREAD_MUTEX_CLOCKLOCK = yes; then - AC_DEFINE(_GLIBCXX_USE_PTHREAD_MUTEX_CLOCKLOCK, 1, [Define if pthread_mutex_clocklock is available in .]) + AC_DEFINE(_GLIBCXX_USE_PTHREAD_MUTEX_CLOCKLOCK, (_GLIBCXX_TSAN==0), [Define if pthread_mutex_clocklock is available in .]) fi CXXFLAGS="$ac_save_CXXFLAGS"