From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A3AF4C35666 for ; Fri, 21 Feb 2020 21:25:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7B34624686 for ; Fri, 21 Feb 2020 21:25:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582320332; bh=9L3zX4koVc32qpAT/bAy03gWL+eJ4yZPBNHEHX9BVO4=; h=From:To:Subject:Date:In-Reply-To:References:In-Reply-To: References:List-ID:From; b=NQX35iZyCNcGdyywtj2yx4V8dsLv8OeQo2D4QWixKANl1ygOlJCSLR1G6S7CvWXkI 0Qh+AbCUCn+HmpR9f2Q/6yDAH2rAxcEYs423J4mEtvxc/1nrgLuLbhLt5HzXuRhgQB RzSYSRdkYPwdwNmQrNUUjMYEEKekj2lv6owUbDww= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729385AbgBUVZa (ORCPT ); Fri, 21 Feb 2020 16:25:30 -0500 Received: from mail.kernel.org ([198.145.29.99]:39210 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729278AbgBUVZ2 (ORCPT ); Fri, 21 Feb 2020 16:25:28 -0500 Received: from localhost.localdomain (c-98-220-238-81.hsd1.il.comcast.net [98.220.238.81]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3917724681; Fri, 21 Feb 2020 21:25:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582320326; bh=9L3zX4koVc32qpAT/bAy03gWL+eJ4yZPBNHEHX9BVO4=; h=From:To:Subject:Date:In-Reply-To:References:In-Reply-To: References:From; b=cBi7WI0zmyqxGaphi9pITUSWgqlOJoyDZkvuLhXFrxymPOsk+7BEcfS+LpLQFDZ80 5XEgHZ1l6oiE/89ubFZcq8X4ZWvTBnVG6hKRIYQbn2kqJG6atSlCLptuTVc2pM8Eeb pl0ztCek4VMqjuF+o7AsibsSKDR5ZygO+1G7WgqE= From: zanussi@kernel.org To: LKML , linux-rt-users , Steven Rostedt , Thomas Gleixner , Carsten Emde , John Kacur , Sebastian Andrzej Siewior , Daniel Wagner , Tom Zanussi Subject: [PATCH RT 12/25] locking/rtmutex: Clean ->pi_blocked_on in the error case Date: Fri, 21 Feb 2020 15:24:40 -0600 Message-Id: X-Mailer: git-send-email 2.14.1 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Peter Zijlstra v4.14.170-rt75-rc1 stable review patch. If anyone has any objections, please let me know. ----------- [ Upstream commit 0be4ea6e3ce693101be0fbd55a0cc7ce238ab2eb ] The function rt_mutex_wait_proxy_lock() cleans ->pi_blocked_on in case of failure (timeout, signal). The same cleanup is required in __rt_mutex_start_proxy_lock(). In both the cases the tasks was interrupted by a signal or timeout while acquiring the lock and after the interruption it longer blocks on the lock. Fixes: 1a1fb985f2e2b ("futex: Handle early deadlock return correctly") Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Tom Zanussi --- kernel/locking/rtmutex.c | 43 +++++++++++++++++++++++++------------------ 1 file changed, 25 insertions(+), 18 deletions(-) diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index 1177f2815040..4bc01a2a9a88 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -2328,6 +2328,26 @@ void rt_mutex_proxy_unlock(struct rt_mutex *lock, rt_mutex_set_owner(lock, NULL); } +static void fixup_rt_mutex_blocked(struct rt_mutex *lock) +{ + struct task_struct *tsk = current; + /* + * RT has a problem here when the wait got interrupted by a timeout + * or a signal. task->pi_blocked_on is still set. The task must + * acquire the hash bucket lock when returning from this function. + * + * If the hash bucket lock is contended then the + * BUG_ON(rt_mutex_real_waiter(task->pi_blocked_on)) in + * task_blocks_on_rt_mutex() will trigger. This can be avoided by + * clearing task->pi_blocked_on which removes the task from the + * boosting chain of the rtmutex. That's correct because the task + * is not longer blocked on it. + */ + raw_spin_lock(&tsk->pi_lock); + tsk->pi_blocked_on = NULL; + raw_spin_unlock(&tsk->pi_lock); +} + /** * __rt_mutex_start_proxy_lock() - Start lock acquisition for another task * @lock: the rt_mutex to take @@ -2400,6 +2420,9 @@ int __rt_mutex_start_proxy_lock(struct rt_mutex *lock, ret = 0; } + if (ret) + fixup_rt_mutex_blocked(lock); + debug_rt_mutex_print_deadlock(waiter); return ret; @@ -2480,7 +2503,6 @@ int rt_mutex_wait_proxy_lock(struct rt_mutex *lock, struct hrtimer_sleeper *to, struct rt_mutex_waiter *waiter) { - struct task_struct *tsk = current; int ret; raw_spin_lock_irq(&lock->wait_lock); @@ -2492,23 +2514,8 @@ int rt_mutex_wait_proxy_lock(struct rt_mutex *lock, * have to fix that up. */ fixup_rt_mutex_waiters(lock); - /* - * RT has a problem here when the wait got interrupted by a timeout - * or a signal. task->pi_blocked_on is still set. The task must - * acquire the hash bucket lock when returning from this function. - * - * If the hash bucket lock is contended then the - * BUG_ON(rt_mutex_real_waiter(task->pi_blocked_on)) in - * task_blocks_on_rt_mutex() will trigger. This can be avoided by - * clearing task->pi_blocked_on which removes the task from the - * boosting chain of the rtmutex. That's correct because the task - * is not longer blocked on it. - */ - if (ret) { - raw_spin_lock(&tsk->pi_lock); - tsk->pi_blocked_on = NULL; - raw_spin_unlock(&tsk->pi_lock); - } + if (ret) + fixup_rt_mutex_blocked(lock); raw_spin_unlock_irq(&lock->wait_lock); -- 2.14.1