From patchwork Mon Dec 7 06:00:05 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Manivannan Sadhasivam X-Patchwork-Id: 11954861 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=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 39A74C433FE for ; Mon, 7 Dec 2020 06:01:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F05FE229C6 for ; Mon, 7 Dec 2020 06:01:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725933AbgLGGBB (ORCPT ); Mon, 7 Dec 2020 01:01:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45978 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725911AbgLGGBB (ORCPT ); Mon, 7 Dec 2020 01:01:01 -0500 Received: from mail-pf1-x443.google.com (mail-pf1-x443.google.com [IPv6:2607:f8b0:4864:20::443]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 223E9C0613D0 for ; Sun, 6 Dec 2020 22:00:21 -0800 (PST) Received: by mail-pf1-x443.google.com with SMTP id 131so8710995pfb.9 for ; Sun, 06 Dec 2020 22:00:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=+idpF1Cpaw9/DMbUpS5qXRNzr1N/vr5SsKMNGSE2vHk=; b=x79cIv8rBUanEoOew+mnd9hYuXueqtvt1P7zhrODyiIZJA0gGZxJlX8ERMYPIaUHkt 6hA/uQTumgor3gmMCC0GvgCUyJmyaHUYeccbYaUimayzV1LA06hrHTckeKReL1DDEsQq 1ktKcI5iii6mqj7t3I2ytqToNYB8rumkBc5lMRZY18skyk26PBraYIJR1c8LA0uw+6gh mIbDG5bh/EocQ/i8OitLQHiCQ4tWSF1rXRoHm1HL9VlKkuRUJnvYJNhHXGxRqgwTliXt lUJ9DP9gjJ2VViDYtV+ZHsIUpbfPeyY+CTK04cQC4+CSxAHHucNUltD4B+VpCC4l/88f TZPQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=+idpF1Cpaw9/DMbUpS5qXRNzr1N/vr5SsKMNGSE2vHk=; b=ctnIJJel6uXCUE4+t2sFaiuU82Po6BHw8lUPrL0MAXikmI4irzUW0WCkTz1KohBr5M jK/hnMAzewphUmZ2c5NQm1sphmlsKspstx8FXNQuxB41OExFYXY+r+/9/GG3dIpGjkuN 1DlYebMkbhsc5vwtZDNlY93LtTM19ZGEhklqU3QIB9xNYBTmq7Y1WkwFFZvNOcB9B5lJ YGW/TheLJPShI4DMEapbB6Jk5VFZXtLqfhoRX4L0eAzyOv+NXm2kfDWbQiJWMSHZn9zK YzbQEQuwd/AZtu1L9toUkWGUAWVEuG6iaVDsHB4LLmBN1dJR34vKoQIu6ckbfRLaw973 ZD6A== X-Gm-Message-State: AOAM5307XQI1uzVEEegBvi+8gngD3/Id6E7j4wec+yzx/bK/39/hzcIa oDG9an8QQXYvpltKGcSAj0I4bA+T9ZMr X-Google-Smtp-Source: ABdhPJyGFxd72bRvqQPuwgeNFZEl7f8JSsSvuxN+jQfdDwk9LX5/0aSNMeOPU5/uajhspNF9NPAZUA== X-Received: by 2002:a63:c46:: with SMTP id 6mr16859201pgm.353.1607320820543; Sun, 06 Dec 2020 22:00:20 -0800 (PST) Received: from localhost.localdomain ([2409:4072:89:c10a:c01b:880c:5d14:a5a4]) by smtp.gmail.com with ESMTPSA id i26sm12953744pfq.148.2020.12.06.22.00.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 06 Dec 2020 22:00:19 -0800 (PST) From: Manivannan Sadhasivam To: wim@linux-watchdog.org, linux@roeck-us.net Cc: agross@kernel.org, bjorn.andersson@linaro.org, linux-arm-msm@vger.kernel.org, linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org, Manivannan Sadhasivam Subject: [PATCH] watchdog: qcom: Avoid context switch in restart handler Date: Mon, 7 Dec 2020 11:30:05 +0530 Message-Id: <20201207060005.21293-1-manivannan.sadhasivam@linaro.org> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-watchdog@vger.kernel.org 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 --- 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 ab7465d186fd..cdf754233e53 100644 --- a/drivers/watchdog/qcom-wdt.c +++ b/drivers/watchdog/qcom-wdt.c @@ -148,7 +148,7 @@ static int qcom_wdt_restart(struct watchdog_device *wdd, unsigned long action, */ wmb(); - msleep(150); + mdelay(150); return 0; }