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 DD734CCA499 for ; Tue, 7 Jun 2022 19:56:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1357550AbiFGTzb (ORCPT ); Tue, 7 Jun 2022 15:55:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47162 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1358864AbiFGTxS (ORCPT ); Tue, 7 Jun 2022 15:53:18 -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 3C2CF25C59; Tue, 7 Jun 2022 11:22:54 -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 BCD296006F; Tue, 7 Jun 2022 18:22:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CD482C34115; Tue, 7 Jun 2022 18:22:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1654626173; bh=1uaTTfwT9pRZAFyjX8pnO9QKdbRItDK/BYxL3WuGbZA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=e53pWkPMz7NOfVF8FTf1KxaRPk69NRIJG+PHYv8TCp81kZjKR8cECAukwwybQ5o2j jktQgHHze+2lbTp+9ZmhPm+1d3Ixyz3ybNEZvrrwNmbapgGeW5VUv+BDNRj/j603ax JNHnbbzpbIwDUcyuOtHfMC3S8JEgrsAu3LG7ji8M= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sebastian Andrzej Siewior , John Ogness , Petr Mladek , Sasha Levin Subject: [PATCH 5.17 282/772] printk: use atomic updates for klogd work Date: Tue, 7 Jun 2022 18:57:54 +0200 Message-Id: <20220607164957.335498853@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220607164948.980838585@linuxfoundation.org> References: <20220607164948.980838585@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@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 833e407545b8..74c92dd70c80 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -3230,7 +3230,7 @@ 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 */ @@ -3264,7 +3264,7 @@ 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(); } -- 2.35.1