From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by sourceware.org (Postfix) with ESMTP id D48563858413 for ; Thu, 26 Aug 2021 14:27:13 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org D48563858413 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-456-_9pgtTz_MFyp_iSAYRV3RA-1; Thu, 26 Aug 2021 10:27:12 -0400 X-MC-Unique: _9pgtTz_MFyp_iSAYRV3RA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 4464E1934101; Thu, 26 Aug 2021 14:27:11 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.194.140]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 681A860877; Thu, 26 Aug 2021 14:27:10 +0000 (UTC) From: Florian Weimer To: Adhemerval Zanella Cc: libc-alpha@sourceware.org Subject: Re: [PATCH v2 12/19] nptl: Use tidlock when accessing TID on pthread_getcpuclockid References: <20210823195047.543237-1-adhemerval.zanella@linaro.org> <20210823195047.543237-13-adhemerval.zanella@linaro.org> Date: Thu, 26 Aug 2021 16:27:08 +0200 In-Reply-To: <20210823195047.543237-13-adhemerval.zanella@linaro.org> (Adhemerval Zanella's message of "Mon, 23 Aug 2021 16:50:40 -0300") Message-ID: <87v93s5lj7.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-12.9 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H2, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) 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: , X-List-Received-Date: Thu, 26 Aug 2021 14:27:14 -0000 * Adhemerval Zanella: > Checked on x86_64-linux-gnu. > --- > nptl/pthread_getcpuclockid.c | 27 +++++++++++++++++---------- > 1 file changed, 17 insertions(+), 10 deletions(-) > > diff --git a/nptl/pthread_getcpuclockid.c b/nptl/pthread_getcpuclockid.c > index 0a6656ea4c..8c0db0b9ba 100644 > --- a/nptl/pthread_getcpuclockid.c > +++ b/nptl/pthread_getcpuclockid.c > @@ -29,16 +29,23 @@ __pthread_getcpuclockid (pthread_t threadid, clockid_t *clockid) > struct pthread *pd = (struct pthread *) threadid; > > /* Make sure the descriptor is valid. */ > - if (INVALID_TD_P (pd)) > - /* Not a valid thread handle. */ > - return ESRCH; > - > - /* The clockid_t value is a simple computation from the TID. */ > - > - const clockid_t tidclock = MAKE_THREAD_CPUCLOCK (pd->tid, CPUCLOCK_SCHED); > - > - *clockid = tidclock; > - return 0; > + sigset_t oldmask; > + __libc_signal_block_all (&oldmask); > + lll_lock (pd->tidlock, LLL_PRIVATE); > + > + int res; > + if (pd->tid != 0) > + { > + *clockid = MAKE_THREAD_CPUCLOCK (pd->tid, CPUCLOCK_SCHED); > + res = 0; > + } > + else > + res = -ESRCH; > + > + lll_unlock (pd->tidlock, LLL_PRIVATE); > + __libc_signal_restore_set (&oldmask); > + > + return res; This doesn't really solve the race, does it? The caller cannot use the clock ID safely. Thanks, Florian