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 7F185394843A for ; Wed, 26 May 2021 18:02:17 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 7F185394843A 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-226-j9IAYwN6O1mOefiaWJQ77A-1; Wed, 26 May 2021 14:02:14 -0400 X-MC-Unique: j9IAYwN6O1mOefiaWJQ77A-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C1AED501E1; Wed, 26 May 2021 18:02:13 +0000 (UTC) Received: from oldenburg.str.redhat.com (ovpn-113-228.ams2.redhat.com [10.36.113.228]) by smtp.corp.redhat.com (Postfix) with ESMTPS id CF3FA1349A; Wed, 26 May 2021 18:02:12 +0000 (UTC) From: Florian Weimer To: Adhemerval Zanella via Libc-alpha Subject: Re: [PATCH 07/11] nptl: Remove CANCELING_BITMASK References: <20210526165728.1772546-1-adhemerval.zanella@linaro.org> <20210526165728.1772546-8-adhemerval.zanella@linaro.org> Date: Wed, 26 May 2021 20:02:10 +0200 In-Reply-To: <20210526165728.1772546-8-adhemerval.zanella@linaro.org> (Adhemerval Zanella via Libc-alpha's message of "Wed, 26 May 2021 13:57:24 -0300") Message-ID: <8735u9qspp.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 10.5.11.11 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-6.7 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H4, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) 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: Wed, 26 May 2021 18:02:18 -0000 * Adhemerval Zanella via Libc-alpha: > The CANCELING_BITMASK is used as an optimization to avoid sending > the signal when pthread_cancel is called in a concurrent manner. > > This requires then to put both the cancellation state and type on > a shared state (cancelhandling), since 'pthread_cancel' checks > whether cancellation is enabled and asynchrnous to either cancel > itself of sending the signal. > > It also requires handle the CANCELING_BITMASK on > __pthread_disable_asynccancel, however this is incurs in the same > issues described on BZ#12683: the cancellation is acting even *after* > the syscalls returns with user visible side-effects. > > This patch removes this optimization and simplifies the pthread > cancellation implementation: pthread_cancel now first check if > cancellation is already pending and if not always send a signal > if the target is not itself. The SIGCANCEL handler is also simpified > since there is not need to setup a CAS loop. =E2=80=9Cand, if not, always sends a signal=E2=80=9D ? > + int ch =3D atomic_load_relaxed (&self->cancelhandling); > + /* Cancelation not enabled, not cancelled, or already exitting. */ Typo: exitting The change itself looks good to me, and I agree with the direction. Thanks, Florian