From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sibi Sankar Subject: [PATCH v4] PM / devfreq: Restart previous governor if new governor fails to start Date: Wed, 12 Dec 2018 19:23:13 +0530 Message-ID: <20181212135313.30268-1-sibis@codeaurora.org> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: Sender: linux-kernel-owner@vger.kernel.org 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, skannan@codeaurora.org, Sibi Sankar List-Id: linux-pm@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. Signed-off-by: Sibi Sankar Signed-off-by: Saravana Kannan Reviewed-by: Chanwoo Choi --- 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 | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c index 141413067b5c..ba2875a0b90e 100644 --- a/drivers/devfreq/devfreq.c +++ b/drivers/devfreq/devfreq.c @@ -1024,7 +1024,7 @@ 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) @@ -1053,12 +1053,19 @@ 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); + df->governor->event_handler(df, DEVFREQ_GOV_START, + 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