From: Leonard Crestez Date: Tue, 24 Sep 2019 07:52:23 +0000 (+0300) Subject: PM / devfreq: Lock devfreq in trans_stat_show X-Git-Tag: v5.4.4~65 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=1b5d4a3a0957dbbd403a3f1ce3a6e23b5d3db2c0;p=platform%2Fkernel%2Flinux-rpi.git PM / devfreq: Lock devfreq in trans_stat_show commit 2abb0d5268ae7b5ddf82099b1f8d5aa8414637d4 upstream. There is no locking in this sysfs show function so stats printing can race with a devfreq_update_status called as part of freq switching or with initialization. Also add an assert in devfreq_update_status to make it clear that lock must be held by caller. Fixes: 39688ce6facd ("PM / devfreq: account suspend/resume for stats") Cc: stable@vger.kernel.org Signed-off-by: Leonard Crestez Reviewed-by: Matthias Kaehlcke Reviewed-by: Chanwoo Choi Signed-off-by: Chanwoo Choi Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c index 446490c9..3a1484e7 100644 --- a/drivers/devfreq/devfreq.c +++ b/drivers/devfreq/devfreq.c @@ -160,6 +160,7 @@ int devfreq_update_status(struct devfreq *devfreq, unsigned long freq) int lev, prev_lev, ret = 0; unsigned long cur_time; + lockdep_assert_held(&devfreq->lock); cur_time = jiffies; /* Immediately exit if previous_freq is not initialized yet. */ @@ -1397,12 +1398,17 @@ static ssize_t trans_stat_show(struct device *dev, int i, j; unsigned int max_state = devfreq->profile->max_state; - if (!devfreq->stop_polling && - devfreq_update_status(devfreq, devfreq->previous_freq)) - return 0; if (max_state == 0) return sprintf(buf, "Not Supported.\n"); + mutex_lock(&devfreq->lock); + if (!devfreq->stop_polling && + devfreq_update_status(devfreq, devfreq->previous_freq)) { + mutex_unlock(&devfreq->lock); + return 0; + } + mutex_unlock(&devfreq->lock); + len = sprintf(buf, " From : To\n"); len += sprintf(buf + len, " :"); for (i = 0; i < max_state; i++)