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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 39DEFC433E0 for ; Mon, 28 Dec 2020 15:37:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0FCD42053B for ; Mon, 28 Dec 2020 15:37:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392898AbgL1Pfr (ORCPT ); Mon, 28 Dec 2020 10:35:47 -0500 Received: from mail.kernel.org ([198.145.29.99]:53602 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2407000AbgL1Nvy (ORCPT ); Mon, 28 Dec 2020 08:51:54 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8D11D20791; Mon, 28 Dec 2020 13:51:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1609163468; bh=ZXI4vzSgiezYX6Z4oK95nPcAMdAI/wIpg2tzE35SBig=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rZHLoDf8PoSwQ91MGanPfv2gXRZ4vtKqGsja2bslv/cqGWIxpxVT0tIsuHYH04yYA FI0NNzB0iR9tFz+LDRk8KzGBtpsY2czaIOoZW2Bt8I10ZXAre2SuBU82puN9jVpvFh r8VwLXF3GEIFSDsjfe71AzZbkFkWdTPLKFub0mJE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Manivannan Sadhasivam , Guenter Roeck , Wim Van Sebroeck , Sasha Levin Subject: [PATCH 5.4 296/453] watchdog: qcom: Avoid context switch in restart handler Date: Mon, 28 Dec 2020 13:48:52 +0100 Message-Id: <20201228124951.447773976@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201228124937.240114599@linuxfoundation.org> References: <20201228124937.240114599@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: linux-kernel@vger.kernel.org From: Manivannan Sadhasivam [ Upstream commit 7948fab26bcc468aa2a76462f441291b5fb0d5c7 ] The use of msleep() in the restart handler will cause scheduler to induce a context switch which is not desirable. This generates below warning on SDX55 when WDT is the only available restart source: [ 39.800188] reboot: Restarting system [ 39.804115] ------------[ cut here ]------------ [ 39.807855] WARNING: CPU: 0 PID: 678 at kernel/rcu/tree_plugin.h:297 rcu_note_context_switch+0x190/0x764 [ 39.812538] Modules linked in: [ 39.821954] CPU: 0 PID: 678 Comm: reboot Not tainted 5.10.0-rc1-00063-g33a9990d1d66-dirty #47 [ 39.824854] Hardware name: Generic DT based system [ 39.833470] [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [ 39.838154] [] (show_stack) from [] (dump_stack+0x8c/0xa0) [ 39.846049] [] (dump_stack) from [] (__warn+0xd8/0xf0) [ 39.853058] [] (__warn) from [] (warn_slowpath_fmt+0x64/0xc8) [ 39.859925] [] (warn_slowpath_fmt) from [] (rcu_note_context_switch+0x190/0x764) [ 39.867503] [] (rcu_note_context_switch) from [] (__schedule+0x84/0x640) [ 39.876685] [] (__schedule) from [] (schedule+0x58/0x10c) [ 39.885095] [] (schedule) from [] (schedule_timeout+0x1e8/0x3d4) [ 39.892135] [] (schedule_timeout) from [] (msleep+0x2c/0x38) [ 39.899947] [] (msleep) from [] (qcom_wdt_restart+0xc4/0xcc) [ 39.907319] [] (qcom_wdt_restart) from [] (watchdog_restart_notifier+0x18/0x28) [ 39.914715] [] (watchdog_restart_notifier) from [] (atomic_notifier_call_chain+0x60/0x84) [ 39.923487] [] (atomic_notifier_call_chain) from [] (machine_restart+0x78/0x7c) [ 39.933551] [] (machine_restart) from [] (__do_sys_reboot+0xdc/0x1e0) [ 39.942397] [] (__do_sys_reboot) from [] (ret_fast_syscall+0x0/0x54) [ 39.950721] Exception stack(0xc3e0bfa8 to 0xc3e0bff0) [ 39.958855] bfa0: 0001221c bed2fe24 fee1dead 28121969 01234567 00000000 [ 39.963832] bfc0: 0001221c bed2fe24 00000003 00000058 000225e0 00000000 00000000 00000000 [ 39.971985] bfe0: b6e62560 bed2fc84 00010fd8 b6e62580 [ 39.980124] ---[ end trace 3f578288bad866e4 ]--- Hence, replace msleep() with mdelay() to fix this issue. Fixes: 05e487d905ab ("watchdog: qcom: register a restart notifier") Signed-off-by: Manivannan Sadhasivam Reviewed-by: Guenter Roeck Link: https://lore.kernel.org/r/20201207060005.21293-1-manivannan.sadhasivam@linaro.org Signed-off-by: Guenter Roeck Signed-off-by: Wim Van Sebroeck Signed-off-by: Sasha Levin --- drivers/watchdog/qcom-wdt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/watchdog/qcom-wdt.c b/drivers/watchdog/qcom-wdt.c index eb47fe5ed2805..ea8a6abd64ecb 100644 --- a/drivers/watchdog/qcom-wdt.c +++ b/drivers/watchdog/qcom-wdt.c @@ -143,7 +143,7 @@ static int qcom_wdt_restart(struct watchdog_device *wdd, unsigned long action, */ wmb(); - msleep(150); + mdelay(150); return 0; } -- 2.27.0