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 [216.205.24.124]) by sourceware.org (Postfix) with ESMTP id 42CD63858402 for ; Thu, 26 Aug 2021 14:38:35 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 42CD63858402 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-269-hw3szze0MBirUWaUB7Lkow-1; Thu, 26 Aug 2021 10:38:33 -0400 X-MC-Unique: hw3szze0MBirUWaUB7Lkow-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 AF845801A92; Thu, 26 Aug 2021 14:38:32 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.194.140]) by smtp.corp.redhat.com (Postfix) with ESMTPS id DD0A6838BC; Thu, 26 Aug 2021 14:38:31 +0000 (UTC) From: Florian Weimer To: Adhemerval Zanella Cc: libc-alpha@sourceware.org Subject: Re: [PATCH v2 15/19] nptl: Use tidlock when accessing TID on pthread_getname_np References: <20210823195047.543237-1-adhemerval.zanella@linaro.org> <20210823195047.543237-16-adhemerval.zanella@linaro.org> Date: Thu, 26 Aug 2021 16:38:29 +0200 In-Reply-To: <20210823195047.543237-16-adhemerval.zanella@linaro.org> (Adhemerval Zanella's message of "Mon, 23 Aug 2021 16:50:43 -0300") Message-ID: <87ilzs5l0a.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=-6.9 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_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 14:38:36 -0000 * Adhemerval Zanella: > + /* Block all signal, since the lock is recursive and used on pthread_cancel > + (which should be async-signal-safe). */ > + sigset_t oldmask; > + __libc_signal_block_all (&oldmask); > + lll_lock (pd->tidlock, LLL_PRIVATE); > > - int fd = __open64_nocancel (fname, O_RDONLY); > - if (fd == -1) > - return errno; > + char fname[sizeof ("/proc/self/task//comm" ) + INT_BUFSIZE_BOUND (pid_t)]; > + __snprintf (fname, sizeof (fname), "/proc/self/task/%d/comm", pd->tid); > > int res = 0; > - ssize_t n = TEMP_FAILURE_RETRY (__read_nocancel (fd, buf, len)); > - if (n < 0) > - res = errno; > - else > + int fd = __open64_nocancel (fname, O_RDONLY); > + if (fd != -1) > { > - if (buf[n - 1] == '\n') > - buf[n - 1] = '\0'; > - else if (n == len) > - res = ERANGE; > + ssize_t n = TEMP_FAILURE_RETRY (__read_nocancel (fd, buf, len)); > + if (n > 0) > + { > + if (buf[n - 1] == '\n') > + buf[n - 1] = '\0'; > + else if (n == len) > + res = ERANGE; > + else > + buf[n] = '\0'; > + } > else > - buf[n] = '\0'; > + res = errno; > + > + __close_nocancel_nostatus (fd); > } > + else > + res = errno; ENOENT for exited threads is inconsistent with ESRCH (or 0) in other cases. I wonder if we should cache the thread name in the TCB. That would be nice for debugging coredumps, too. Thanks, Florian