From mboxrd@z Thu Jan 1 00:00:00 1970 From: Saravana Kannan Subject: Re: [PATCH v2] PM / devfreq: Restart previous governor if new governor fails to start Date: Wed, 26 Oct 2016 12:17:24 -0700 Message-ID: <58110144.9020909@codeaurora.org> References: <1477445160-990-1-git-send-email-skannan@codeaurora.org> <581059C8.3000408@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Return-path: Received: from smtp.codeaurora.org ([198.145.29.96]:57836 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932942AbcJZTRb (ORCPT ); Wed, 26 Oct 2016 15:17:31 -0400 In-Reply-To: <581059C8.3000408@samsung.com> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Chanwoo Choi Cc: "Rafael J. Wysocki" , MyungJoo Ham , Kyungmin Park , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org On 10/26/2016 12:22 AM, Chanwoo Choi wrote: > Hi, > > On 2016년 10월 26일 10:25, Saravana Kannan wrote: >> 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 >> --- >> * 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); >> + } Sigh... looks like I added the changes to the index but forgot to commit it before I sent the patch. Will send v3. >> out: >> mutex_unlock(&devfreq_list_lock); >> >> > > Looks good to me. > But, how about using the 'prev_governor' instead of 'prev_gov'? > because the variable name of current governor is 'governor' instead of 'gov'. I was trying to avoid wrapping lines too much. But this doesn't cause any additional wraps. Done. > > Reviewed-by: Chanwoo Choi > Can you please review v3? Thanks, Saravana -- Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project