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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: 39688ce6fa ("PM / devfreq: account suspend/resume for stats")
Cc: stable@vger.kernel.org
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Leonard Crestez 2019-09-24 10:52:23 +03:00 committed by Greg Kroah-Hartman
parent 40c3c38932
commit 1b5d4a3a09
1 changed files with 9 additions and 3 deletions
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12
drivers/devfreq/devfreq.c
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@ -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++)