Commit 2abb0d52 authored by Leonard Crestez's avatar Leonard Crestez Committed by Chanwoo Choi

PM / devfreq: Lock devfreq in trans_stat_show

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: 39688ce6 ("PM / devfreq: account suspend/resume for stats")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarLeonard Crestez <leonard.crestez@nxp.com>
Reviewed-by: default avatarMatthias Kaehlcke <mka@chromium.org>
Reviewed-by: default avatarChanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: default avatarChanwoo Choi <cw00.choi@samsung.com>
parent d68adc8f
......@@ -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++)
......
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