From patchwork Fri Aug 4 18:53:34 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michael Tokarev X-Patchwork-Id: 1817068 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4RHZfR2g1Dz1ybS for ; Sat, 5 Aug 2023 04:55:27 +1000 (AEST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qRzwG-0002J3-L2; Fri, 04 Aug 2023 14:54:16 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qRzwE-0002Hh-RU; Fri, 04 Aug 2023 14:54:14 -0400 Received: from isrv.corpit.ru ([86.62.121.231]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qRzwD-00088a-5S; Fri, 04 Aug 2023 14:54:14 -0400 Received: from tsrv.corpit.ru (tsrv.tls.msk.ru [192.168.177.2]) by isrv.corpit.ru (Postfix) with ESMTP id 6DDBA1840B; Fri, 4 Aug 2023 21:54:18 +0300 (MSK) Received: from tls.msk.ru (mjt.wg.tls.msk.ru [192.168.177.130]) by tsrv.corpit.ru (Postfix) with SMTP id E9D0C1B882; Fri, 4 Aug 2023 21:53:57 +0300 (MSK) Received: (nullmailer pid 1874215 invoked by uid 1000); Fri, 04 Aug 2023 18:53:56 -0000 From: Michael Tokarev To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Anthony PERARD , Stefan Hajnoczi , Michael Tokarev Subject: [Stable-7.2.5 21/36] thread-pool: signal "request_cond" while locked Date: Fri, 4 Aug 2023 21:53:34 +0300 Message-Id: <20230804185350.1874133-8-mjt@tls.msk.ru> X-Mailer: git-send-email 2.39.2 In-Reply-To: References: MIME-Version: 1.0 Received-SPF: pass client-ip=86.62.121.231; envelope-from=mjt@tls.msk.ru; helo=isrv.corpit.ru X-Spam_score_int: -68 X-Spam_score: -6.9 X-Spam_bar: ------ X-Spam_report: (-6.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_HI=-5, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org From: Anthony PERARD thread_pool_free() might have been called on the `pool`, which would be a reason for worker_thread() to quit. In this case, `pool->request_cond` is been destroyed. If worker_thread() didn't managed to signal `request_cond` before it been destroyed by thread_pool_free(), we got: util/qemu-thread-posix.c:198: qemu_cond_signal: Assertion `cond->initialized' failed. One backtrace: __GI___assert_fail (assertion=0x55555614abcb "cond->initialized", file=0x55555614ab88 "util/qemu-thread-posix.c", line=198, function=0x55555614ad80 <__PRETTY_FUNCTION__.17104> "qemu_cond_signal") at assert.c:101 qemu_cond_signal (cond=0x7fffb800db30) at util/qemu-thread-posix.c:198 worker_thread (opaque=0x7fffb800dab0) at util/thread-pool.c:129 qemu_thread_start (args=0x7fffb8000b20) at util/qemu-thread-posix.c:505 start_thread (arg=) at pthread_create.c:486 Reported here: https://lore.kernel.org/all/ZJwoK50FcnTSfFZ8@MacBook-Air-de-Roger.local/T/#u To avoid issue, keep lock while sending a signal to `request_cond`. Fixes: 900fa208f506 ("thread-pool: replace semaphore with condition variable") Signed-off-by: Anthony PERARD Reviewed-by: Stefan Hajnoczi Message-Id: <20230714152720.5077-1-anthony.perard@citrix.com> Signed-off-by: Anthony PERARD (cherry picked from commit f4f71363fcdb1092ff64d2bba6f9af39570c2f2b) Signed-off-by: Michael Tokarev diff --git a/util/thread-pool.c b/util/thread-pool.c index 31113b5860..39accc9ebe 100644 --- a/util/thread-pool.c +++ b/util/thread-pool.c @@ -120,13 +120,13 @@ static void *worker_thread(void *opaque) pool->cur_threads--; qemu_cond_signal(&pool->worker_stopped); - qemu_mutex_unlock(&pool->lock); /* * Wake up another thread, in case we got a wakeup but decided * to exit due to pool->cur_threads > pool->max_threads. */ qemu_cond_signal(&pool->request_cond); + qemu_mutex_unlock(&pool->lock); return NULL; }