From patchwork Wed Oct 26 19:17:05 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Saravana Kannan X-Patchwork-Id: 9398035 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 EDE9560231 for ; Wed, 26 Oct 2016 19:17:16 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BEF9229C39 for ; Wed, 26 Oct 2016 19:17:16 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B3DB929D2A; Wed, 26 Oct 2016 19:17:16 +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 4CA1D29C39 for ; Wed, 26 Oct 2016 19:17:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753120AbcJZTRO (ORCPT ); Wed, 26 Oct 2016 15:17:14 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:57710 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752099AbcJZTRN (ORCPT ); Wed, 26 Oct 2016 15:17:13 -0400 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 7AF7461506; Wed, 26 Oct 2016 19:17:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1477509432; bh=KjQq9zEKXXauIxLdNAdEh0GrpefyfJWNG7uafLd31uM=; h=From:To:Cc:Subject:Date:From; b=kUr/dxNc6S+NtBsJ7tL6YUfeEurRZ3fnaLEtcQNaSP39VdluWb3QeHfm9e6VPKyrR x69H30acrkojAJyKJ/KFi/WWUb00WdKdofcIZPMI9RLY0tbBQQGGeqiYPSsCaPHmmX Gk4yLZI4lUOICZiMuNI7YNzGURDFNA+6Z3LMgtV0= 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 89E5161506; Wed, 26 Oct 2016 19:17:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1477509431; bh=KjQq9zEKXXauIxLdNAdEh0GrpefyfJWNG7uafLd31uM=; h=From:To:Cc:Subject:Date:From; b=HgfEAunrmZ0bCb+VGs3d15W2QI6+9xhWaA1eN8fzcWmPOOnlFZcLNfEOReAvhMTPf JCvc6EN5ZXrpVM6x8afvJbqXBXJSGvaFqZcqmZBbjPkKz1pyRrYQx+WWwAKpY3/u1X /fUa6dF905NyB12/ZoLqvMCcer5xAlXC/Lt9MfrA= DMARC-Filter: OpenDMARC Filter v1.3.1 smtp.codeaurora.org 89E5161506 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 , cw00.choi@samsung.com Subject: [PATCH v3] PM / devfreq: Restart previous governor if new governor fails to start Date: Wed, 26 Oct 2016 12:17:05 -0700 Message-Id: <1477509425-16936-1-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 --- * Fix NULL deref for real this time. * Addressed some style preferences. drivers/devfreq/devfreq.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c index bf3ea76..77c41a5 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_governor; ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor); if (ret != 1) @@ -944,12 +944,21 @@ 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); + if (prev_governor) { + 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);