From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932232AbeAWV6g (ORCPT ); Tue, 23 Jan 2018 16:58:36 -0500 Received: from hqemgate14.nvidia.com ([216.228.121.143]:16981 "EHLO hqemgate14.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932071AbeAWV6e (ORCPT ); Tue, 23 Jan 2018 16:58:34 -0500 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Tue, 23 Jan 2018 13:58:34 -0800 From: Bo Yan To: , , CC: , , Bo Yan Subject: [PATCH] cpufreq: skip cpufreq resume if it's not suspended Date: Tue, 23 Jan 2018 13:57:55 -0800 Message-ID: <1516744675-21233-1-git-send-email-byan@nvidia.com> X-Mailer: git-send-email 2.7.4 X-NVConfidentiality: public MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org cpufreq_resume can be called even without preceding cpufreq_suspend. This can happen in following scenario: suspend_devices_and_enter --> dpm_suspend_start --> dpm_prepare --> device_prepare : this function errors out --> dpm_suspend: this is skipped due to dpm_prepare failure this means cpufreq_suspend is skipped over --> goto Recover_platform, due to previous error --> goto Resume_devices --> dpm_resume_end --> dpm_resume --> cpufreq_resume In case schedutil is used as frequency governor, cpufreq_resume will eventually call sugov_start, which does following: memset(sg_cpu, 0, sizeof(*sg_cpu)); .... This effectively erases function pointer for frequency update, causing crash later on. The function pointer would have been set correctly if subsequent cpufreq_add_update_util_hook runs successfully, but that function returns earlier because cpufreq_suspend was not called: if (WARN_ON(per_cpu(cpufreq_update_util_data, cpu))) return; Ideally, suspend should succeed, then things will be fine. But even in case of suspend failure, system should not crash. The fix is to check cpufreq_suspended first, if it's false, that means cpufreq_suspend was not called in the first place, so do not resume cpufreq. Signed-off-by: Bo Yan --- drivers/cpufreq/cpufreq.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 41d148af7748..95b1c4afe14e 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1680,6 +1680,10 @@ void cpufreq_resume(void) if (!cpufreq_driver) return; + if (unlikely(!cpufreq_suspended)) { + pr_warn("%s: resume after failing suspend\n", __func__); + return; + } cpufreq_suspended = false; if (!has_target() && !cpufreq_driver->resume) -- 2.7.4