From patchwork Thu Sep 24 13:40:49 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Martin Wilck X-Patchwork-Id: 11797489 X-Patchwork-Delegate: christophe.varoqui@free.fr Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1368D92C for ; Thu, 24 Sep 2020 13:46:22 +0000 (UTC) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [63.128.21.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B2EB1206B2 for ; Thu, 24 Sep 2020 13:46:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B2EB1206B2 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=tempfail smtp.mailfrom=dm-devel-bounces@redhat.com 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-398-vjmnAcLhPi2A5GrbqzrduQ-1; Thu, 24 Sep 2020 09:46:17 -0400 X-MC-Unique: vjmnAcLhPi2A5GrbqzrduQ-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1EFF9800493; Thu, 24 Sep 2020 13:46:13 +0000 (UTC) Received: from colo-mx.corp.redhat.com (colo-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.20]) by smtp.corp.redhat.com (Postfix) with ESMTPS id AB30C5D9D3; Thu, 24 Sep 2020 13:46:12 +0000 (UTC) Received: from lists01.pubmisc.prod.ext.phx2.redhat.com (lists01.pubmisc.prod.ext.phx2.redhat.com [10.5.19.33]) by colo-mx.corp.redhat.com (Postfix) with ESMTP id 7BD0E1826D2C; Thu, 24 Sep 2020 13:46:12 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) by lists01.pubmisc.prod.ext.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id 08ODfmQ4026894 for ; Thu, 24 Sep 2020 09:41:48 -0400 Received: by smtp.corp.redhat.com (Postfix) id 93CBC10064E1; Thu, 24 Sep 2020 13:41:48 +0000 (UTC) Delivered-To: dm-devel@redhat.com Received: from mimecast-mx02.redhat.com (mimecast03.extmail.prod.ext.rdu2.redhat.com [10.11.55.19]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 8E7F5100619B for ; Thu, 24 Sep 2020 13:41:48 +0000 (UTC) Received: from us-smtp-1.mimecast.com (us-smtp-1.mimecast.com [205.139.110.61]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 765E5811E94 for ; Thu, 24 Sep 2020 13:41:48 +0000 (UTC) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-40-hmMZwNuSOCiJpx4O-5mGeg-1; Thu, 24 Sep 2020 09:41:43 -0400 X-MC-Unique: hmMZwNuSOCiJpx4O-5mGeg-1 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id EEDD2B183; Thu, 24 Sep 2020 13:41:41 +0000 (UTC) From: mwilck@suse.com To: Christophe Varoqui , Benjamin Marzinski Date: Thu, 24 Sep 2020 15:40:49 +0200 Message-Id: <20200924134054.14632-19-mwilck@suse.com> In-Reply-To: <20200924134054.14632-1-mwilck@suse.com> References: <20200924134054.14632-1-mwilck@suse.com> MIME-Version: 1.0 X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-MIME-Autoconverted: from quoted-printable to 8bit by lists01.pubmisc.prod.ext.phx2.redhat.com id 08ODfmQ4026894 X-loop: dm-devel@redhat.com Cc: lixiaokeng@huawei.com, dm-devel@redhat.com, Martin Wilck Subject: [dm-devel] [PATCH 18/23] libmultipath: fix log_thread startup and teardown X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com From: Martin Wilck This fixes several issues with the log_thread. First, the running flag logq_running should be set by the thread itself, not by log_thread_start()/_stop(). Second, the thread was both cancelled and terminated via a flag (again, logq_running). It's sufficient, and better, to just cancel it and use logq_running as indication for successful termination. Third, the locking wasn't cancel-safe in some places. Forth, log_thread_start() and log_thread_stop() didn't wait for startup/teardown properly. Fifth, using (pthread_t)0 is wrong (pthread_t is opaque; there's no guarantee that 0 is not a valid pthread_t value). Finally, pthread_cancel() was called under logq_lock, which doesn't make sense to me at all. Signed-off-by: Martin Wilck --- libmultipath/log_pthread.c | 59 ++++++++++++++++++++++++++++---------- 1 file changed, 44 insertions(+), 15 deletions(-) diff --git a/libmultipath/log_pthread.c b/libmultipath/log_pthread.c index 0c327ff..5825e66 100644 --- a/libmultipath/log_pthread.c +++ b/libmultipath/log_pthread.c @@ -13,6 +13,7 @@ #include "log_pthread.h" #include "log.h" #include "lock.h" +#include "util.h" static pthread_t log_thr; @@ -56,28 +57,45 @@ static void flush_logqueue (void) } while (empty == 0); } +static void cleanup_log_thread(__attribute((unused)) void *arg) +{ + logdbg(stderr, "log thread exiting"); + pthread_mutex_lock(&logev_lock); + logq_running = 0; + pthread_cond_signal(&logev_cond); + pthread_mutex_unlock(&logev_lock); +} + static void * log_thread (__attribute__((unused)) void * et) { int running; pthread_mutex_lock(&logev_lock); - logq_running = 1; + running = logq_running; + if (!running) + logq_running = 1; + pthread_cond_signal(&logev_cond); pthread_mutex_unlock(&logev_lock); + if (running) + /* already started */ + return NULL; + pthread_cleanup_push(cleanup_log_thread, NULL); mlockall(MCL_CURRENT | MCL_FUTURE); logdbg(stderr,"enter log_thread\n"); while (1) { pthread_mutex_lock(&logev_lock); - if (logq_running && !log_messages_pending) + pthread_cleanup_push(cleanup_mutex, &logev_lock); + while (!log_messages_pending) + /* this is a cancellation point */ pthread_cond_wait(&logev_cond, &logev_lock); log_messages_pending = 0; - running = logq_running; - pthread_mutex_unlock(&logev_lock); - if (!running) - break; + pthread_cleanup_pop(1); + flush_logqueue(); } + pthread_cleanup_pop(1); return NULL; } @@ -98,6 +116,12 @@ void log_thread_start (pthread_attr_t *attr) exit(1); } + pthread_mutex_lock(&logev_lock); + pthread_cleanup_push(cleanup_mutex, &logev_lock); + /* wait for thread startup */ + while (!logq_running) + pthread_cond_wait(&logev_cond, &logev_lock); + pthread_cleanup_pop(1); return; } @@ -112,21 +136,26 @@ void log_thread_reset (void) void log_thread_stop (void) { + int running; + if (!la) return; - logdbg(stderr,"enter log_thread_stop\n"); pthread_mutex_lock(&logev_lock); - logq_running = 0; - pthread_cond_signal(&logev_cond); - pthread_mutex_unlock(&logev_lock); + pthread_cleanup_push(cleanup_mutex, &logev_lock); + running = logq_running; + if (running) { + pthread_cancel(log_thr); + pthread_cond_signal(&logev_cond); + } + while (logq_running) + pthread_cond_wait(&logev_cond, &logev_lock); + pthread_cleanup_pop(1); + + if (running) + pthread_join(log_thr, NULL); - pthread_mutex_lock(&logq_lock); - pthread_cancel(log_thr); - pthread_mutex_unlock(&logq_lock); - pthread_join(log_thr, NULL); - log_thr = (pthread_t)0; flush_logqueue();