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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C0BEFC43217 for ; Wed, 30 Mar 2022 12:06:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345806AbiC3MET (ORCPT ); Wed, 30 Mar 2022 08:04:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57632 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345330AbiC3LyX (ORCPT ); Wed, 30 Mar 2022 07:54:23 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 062672D1D6; Wed, 30 Mar 2022 04:50:57 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 8FD9D61703; Wed, 30 Mar 2022 11:50:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0166EC36AE3; Wed, 30 Mar 2022 11:50:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1648641056; bh=ASULGKKmHDa2iLmKRj2xi0w6Ak4VHMf9fmkjm688PI8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ly9vuDyYKkngsZ8q9YhX/G9WlUVg7/1lcOTMhSeQGUahOfIoksitf+rYGZIv/0ggJ w9gCBYCSEniD/jydWidbaPAKgJZXloGyKzRCfpWK4mBs2hMu7eIZGLgB+ct5RZ2cwT bMiZeb2wD6Z2QcvqxTSdmnH3YFaTmmB1w2+8C5I4rMlSSJ/GKgWqBU/L8/LbiH/jQ9 wyZ6Nmg+r015ve70J9SzW3g1fsG9xq8+ywQdfP6Zm7wenNpA9lwYFk6OoWBq3TT9hj TBY7rb/QylFl69j3MfOVz2/Gl0Q6gjnyNZeAqIRj2fyQ1IIG2FKsPk+Q4SgdjT0Nsj qcLppjSnWeYFg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: John Ogness , Sebastian Andrzej Siewior , Petr Mladek , Sasha Levin , senozhatsky@chromium.org, gregkh@linuxfoundation.org, linux@roeck-us.net, stephen.s.brennan@oracle.com Subject: [PATCH AUTOSEL 5.15 33/50] printk: use atomic updates for klogd work Date: Wed, 30 Mar 2022 07:49:47 -0400 Message-Id: <20220330115005.1671090-33-sashal@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220330115005.1671090-1-sashal@kernel.org> References: <20220330115005.1671090-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: John Ogness [ Upstream commit 2ba3673d70178bf07fb75ff25c54bc478add4021 ] The per-cpu @printk_pending variable can be updated from sleepable contexts, such as: get_random_bytes() warn_unseeded_randomness() printk_deferred() defer_console_output() and can be updated from interrupt contexts, such as: handle_irq_event_percpu() __irq_wake_thread() wake_up_process() try_to_wake_up() select_task_rq() select_fallback_rq() printk_deferred() defer_console_output() and can be updated from NMI contexts, such as: vprintk() if (in_nmi()) defer_console_output() Therefore the atomic variant of the updating functions must be used. Replace __this_cpu_xchg() with this_cpu_xchg(). Replace __this_cpu_or() with this_cpu_or(). Reported-by: Sebastian Andrzej Siewior Signed-off-by: John Ogness Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/87iltld4ue.fsf@jogness.linutronix.de Signed-off-by: Sasha Levin --- kernel/printk/printk.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 34bdc51f4cb3..0677882afb16 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -3256,7 +3256,7 @@ static DEFINE_PER_CPU(int, printk_pending); static void wake_up_klogd_work_func(struct irq_work *irq_work) { - int pending = __this_cpu_xchg(printk_pending, 0); + int pending = this_cpu_xchg(printk_pending, 0); if (pending & PRINTK_PENDING_OUTPUT) { /* If trylock fails, someone else is doing the printing */ @@ -3290,7 +3290,7 @@ void defer_console_output(void) return; preempt_disable(); - __this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT); + this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT); irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); preempt_enable(); } -- 2.34.1