From patchwork Wed Dec 12 13:53:13 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sibi Sankar X-Patchwork-Id: 10726429 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 3287914E2 for ; Wed, 12 Dec 2018 13:53:30 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 20F952B340 for ; Wed, 12 Dec 2018 13:53:30 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 14CD32B354; Wed, 12 Dec 2018 13:53:30 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.7 required=2.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7EC9F2B340 for ; Wed, 12 Dec 2018 13:53:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726263AbeLLNx2 (ORCPT ); Wed, 12 Dec 2018 08:53:28 -0500 Received: from smtp.codeaurora.org ([198.145.29.96]:58830 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726232AbeLLNx2 (ORCPT ); Wed, 12 Dec 2018 08:53:28 -0500 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id C3B1560208; Wed, 12 Dec 2018 13:53:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1544622807; bh=4Ljmm43+EIbj0PFzXA1VtUmyW7AyAprFpeVOkY/z+O4=; h=From:To:Cc:Subject:Date:From; b=PrlbzN+YWUU22Mgz7TrltaqpoZObrjZOMjKyG/DWoAENnSoByeBdWGAu2Mt5Wa0/M BSonkP7CGFd3hLFccz89RxXezBCLCHHAWTWzawLenNzHpKU4A/knlwXi/oC2fgrpU9 RxJHnTZaD76mxeoylPANVmhP/Z/MIkJVeOTsPPL0= Received: from blr-ubuntu-87.qualcomm.com (blr-bdr-fw-01_globalnat_allzones-outside.qualcomm.com [103.229.18.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: sibis@smtp.codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id C45E6601D7; Wed, 12 Dec 2018 13:53:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1544622807; bh=4Ljmm43+EIbj0PFzXA1VtUmyW7AyAprFpeVOkY/z+O4=; h=From:To:Cc:Subject:Date:From; b=PrlbzN+YWUU22Mgz7TrltaqpoZObrjZOMjKyG/DWoAENnSoByeBdWGAu2Mt5Wa0/M BSonkP7CGFd3hLFccz89RxXezBCLCHHAWTWzawLenNzHpKU4A/knlwXi/oC2fgrpU9 RxJHnTZaD76mxeoylPANVmhP/Z/MIkJVeOTsPPL0= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org C45E6601D7 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=sibis@codeaurora.org From: Sibi Sankar To: myungjoo.ham@samsung.com, kyungmin.park@samsung.com Cc: cw00.choi@samsung.com, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm-owner@vger.kernel.org, skannan@codeaurora.org, Sibi Sankar Subject: [PATCH v4] PM / devfreq: Restart previous governor if new governor fails to start Date: Wed, 12 Dec 2018 19:23:13 +0530 Message-Id: <20181212135313.30268-1-sibis@codeaurora.org> X-Mailer: git-send-email 2.19.1 MIME-Version: 1.0 Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Saravana Kannan If the new governor fails to start, switch back to old governor so that the devfreq state is not left in some weird limbo. Signed-off-by: Sibi Sankar Signed-off-by: Saravana Kannan Reviewed-by: Chanwoo Choi --- V4: * Removed prev_governor check. V3: * Fix NULL deref for real this time. * Addressed some style preferences. V2: * Fixed typo in commit text * Fixed potential NULL deref drivers/devfreq/devfreq.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c index 141413067b5c..ba2875a0b90e 100644 --- a/drivers/devfreq/devfreq.c +++ b/drivers/devfreq/devfreq.c @@ -1024,7 +1024,7 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr, struct devfreq *df = to_devfreq(dev); int ret; char str_governor[DEVFREQ_NAME_LEN + 1]; - struct devfreq_governor *governor; + const struct devfreq_governor *governor, *prev_governor; ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor); if (ret != 1) @@ -1053,12 +1053,19 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr, goto out; } } + prev_governor = df->governor; df->governor = governor; strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN); ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL); - if (ret) + if (ret) { dev_warn(dev, "%s: Governor %s not started(%d)\n", __func__, df->governor->name, ret); + df->governor = prev_governor; + strncpy(df->governor_name, prev_governor->name, + DEVFREQ_NAME_LEN); + df->governor->event_handler(df, DEVFREQ_GOV_START, + NULL); + } out: mutex_unlock(&devfreq_list_lock);