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=-8.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 1056CC43381 for ; Mon, 11 Mar 2019 10:07:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D19D720657 for ; Mon, 11 Mar 2019 10:07:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="gDWb1CiP"; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="das9v3vY" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727182AbfCKKH5 (ORCPT ); Mon, 11 Mar 2019 06:07:57 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:51074 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726074AbfCKKH5 (ORCPT ); Mon, 11 Mar 2019 06:07:57 -0400 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 801FB61A8B; Mon, 11 Mar 2019 10:07:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1552298875; bh=ZXuDXx5vm5dKU06DRLzLdanZL3vAsQ2wV2uqPqiv4ow=; h=From:To:Cc:Subject:Date:From; b=gDWb1CiPJjZ3MbY2kaK4KLWM8Gdl9k+agkbh4yqbpAw3geb8mpEw5MwDnFDAe+BGo kQV8FMUTkAz8rsswk2SIXuGSAIEaz8PNA/3uARl6Ea3/gUc/40kDv1SexoIzhVyqWq mHdhisZpiELNnarVR8EN160P8Q0IpKIpA+yFcz8k= 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 DDE5C61A8B; Mon, 11 Mar 2019 10:07:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1552298874; bh=ZXuDXx5vm5dKU06DRLzLdanZL3vAsQ2wV2uqPqiv4ow=; h=From:To:Cc:Subject:Date:From; b=das9v3vYsfFz57R7HAFAE+S/RNT8TufPphjVliBMfpkZcCzjXstskkMm7L9wllu1c zKZjDPd+mj3+slUkoqL0goLmXIvgq0lzpmYBdN9A+z8GafptakKLyAcqhuKW8AyLV4 oWmuzHn76pDT4MXSwF1x5bNS8V4pybTJd2G3w1ms= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org DDE5C61A8B 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, Saravana Kannan , Sibi Sankar Subject: [PATCH v5] PM / devfreq: Restart previous governor if new governor fails to start Date: Mon, 11 Mar 2019 15:36:30 +0530 Message-Id: <20190311100630.12952-1-sibis@codeaurora.org> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. [Mjungjoo: assume fatal on revert failure and set df->governor to NULL] Signed-off-by: Sibi Sankar Signed-off-by: Saravana Kannan Reviewed-by: Chanwoo Choi --- V5: * assume fatal on revert failure and set df->governor to NULL 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 | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c index 428a1de81008..37490235ec34 100644 --- a/drivers/devfreq/devfreq.c +++ b/drivers/devfreq/devfreq.c @@ -1124,7 +1124,7 @@ 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) @@ -1153,12 +1153,24 @@ 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); + ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL); + if (ret) { + dev_warn(dev, + "%s: reverting to Governor %s failed (%d)\n", + __func__, df->governor_name, ret); + df->governor = NULL; + } + } out: mutex_unlock(&devfreq_list_lock); -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project