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Commit b1d06da3 authored by Leonard Crestez's avatar Leonard Crestez Committed by Greg Kroah-Hartman
Browse files

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: 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>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 1fce7e81

drivers/devfreq/devfreq.c

+9 −3
Original line number Diff line number Diff line
@@ -163,6 +163,7 @@ 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. */
@@ -1287,12 +1288,17 @@ 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++)