From patchwork Mon Mar 11 10:06:30 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sibi Sankar X-Patchwork-Id: 10847217 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 D5596139A for ; Mon, 11 Mar 2019 10:07:58 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BFA6629002 for ; Mon, 11 Mar 2019 10:07:58 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B2D8A29008; Mon, 11 Mar 2019 10:07:58 +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 1BC4229002 for ; Mon, 11 Mar 2019 10:07:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726623AbfCKKH5 (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 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. [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 Acked-by: MyungJoo Ham --- 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);