From patchwork Wed Oct 26 01:25:59 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Saravana Kannan X-Patchwork-Id: 9395777 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 956FF60231 for ; Wed, 26 Oct 2016 01:26:13 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6940F29758 for ; Wed, 26 Oct 2016 01:26:09 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 5C8592975A; Wed, 26 Oct 2016 01:26:09 +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=-6.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID 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 9F81E29758 for ; Wed, 26 Oct 2016 01:26:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752959AbcJZB0H (ORCPT ); Tue, 25 Oct 2016 21:26:07 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:42538 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752215AbcJZB0G (ORCPT ); Tue, 25 Oct 2016 21:26:06 -0400 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 63B816160E; Wed, 26 Oct 2016 01:26:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1477445166; bh=IIvdkC/1p7MCaDNWvKa3vGTaKc+HvYq9G0sWQalqGHM=; h=From:To:Cc:Subject:Date:From; b=a/d921yDkmU65EHHm9wQpo6KbpoOJ76Cwuy+XInIOfjcVdwkuaQP7LIEoky57oi3F jrNsN3wgPxBtyZzyBx0E6h68O/sfSiGjcgm6uF1J0pHP7tIb7MSrSreH3MHao+vU6T 7DjtNmAEMRaFD15lNuK3NtSn8ntm7Z940sSFMpgU= Received: from skannan1-linux.qualcomm.com (i-global254.qualcomm.com [199.106.103.254]) (using TLSv1.1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: skannan@smtp.codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id A3E836160E; Wed, 26 Oct 2016 01:26:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1477445165; bh=IIvdkC/1p7MCaDNWvKa3vGTaKc+HvYq9G0sWQalqGHM=; h=From:To:Cc:Subject:Date:From; b=hb+KL41PHaGKWVqWDhBj2pSVT/PPb0so3cXLJdRdKU75A/KkhZ15lTyWXQlnDxKAe be5CTIJHD0CZ/Mtf+15nHAZA1i3Nf5LxxlrvwlEcZOBsEN6sjR/QS4TeJ++8WKyuLW gfLi7hhrCGPKkB6AZNetuIYxWfhqwYhsQnxUQF4o= DMARC-Filter: OpenDMARC Filter v1.3.1 smtp.codeaurora.org A3E836160E Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=pass smtp.mailfrom=skannan@codeaurora.org From: Saravana Kannan To: "Rafael J. Wysocki" , MyungJoo Ham , Kyungmin Park , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Saravana Kannan Subject: [PATCH v2] PM / devfreq: Restart previous governor if new governor fails to start Date: Tue, 25 Oct 2016 18:25:59 -0700 Message-Id: <1477445160-990-1-git-send-email-skannan@codeaurora.org> X-Mailer: git-send-email 1.8.2.1 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 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: Saravana Kannan Reviewed-by: Chanwoo Choi --- * Fixed typo in commit text * Fixed potential NULL deref drivers/devfreq/devfreq.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c index bf3ea76..243253e 100644 --- a/drivers/devfreq/devfreq.c +++ b/drivers/devfreq/devfreq.c @@ -919,7 +919,7 @@ 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_gov; ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor); if (ret != 1) @@ -944,12 +944,17 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr, goto out; } } + prev_gov = 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_gov; + strncpy(df->governor_name, prev_gov->name, DEVFREQ_NAME_LEN); + df->governor->event_handler(df, DEVFREQ_GOV_START, NULL); + } out: mutex_unlock(&devfreq_list_lock);