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Commit e35d35a1 authored by Saravana Kannan's avatar Saravana Kannan Committed by MyungJoo Ham
Browse files

PM / devfreq: Rewrite devfreq_update_status() to fix multiple bugs 



The current devfreq_update_status() has the following bugs:
- If previous frequency doesn't have a valid level, it does an out of bounds
  access into the trans_table and causes memory corruption.
- When the new frequency doesn't have a valid level, the time spent in the
  new frequency is counted towards the next valid frequency switch instead of
  being ignored.
- The time spent on the previous frequency is added to the new frequency's
  stats instead of the previous frequency's stats.

This patch fixes all of this.

Signed-off-by: default avatarSaravana Kannan <skannan@codeaurora.org>
Signed-off-by: default avatarMyungJoo Ham <myungjoo.ham@samsung.com>
parent dcb99fd9

drivers/devfreq/devfreq.c

+20 −11
Original line number Original line Diff line number Diff line
@@ -91,26 +91,35 @@ static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq) 
 */

 */

static int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)

static int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)

{

{

	int lev, prev_lev;

	int lev, prev_lev, ret = 0;

	unsigned long cur_time;

	unsigned long cur_time;





	lev = devfreq_get_freq_level(devfreq, freq);

	if (lev < 0)

		return lev;



	cur_time = jiffies;

	cur_time = jiffies;

	devfreq->time_in_state[lev] +=



	prev_lev = devfreq_get_freq_level(devfreq, devfreq->previous_freq);

	if (prev_lev < 0) {

		ret = prev_lev;

		goto out;

	}



	devfreq->time_in_state[prev_lev] +=

			 cur_time - devfreq->last_stat_updated;

			 cur_time - devfreq->last_stat_updated;

	if (freq != devfreq->previous_freq) {



		prev_lev = devfreq_get_freq_level(devfreq,

	lev = devfreq_get_freq_level(devfreq, freq);

						devfreq->previous_freq);

	if (lev < 0) {

		ret = lev;

		goto out;

	}



	if (lev != prev_lev) {

		devfreq->trans_table[(prev_lev *

		devfreq->trans_table[(prev_lev *

				devfreq->profile->max_state) + lev]++;

				devfreq->profile->max_state) + lev]++;

		devfreq->total_trans++;

		devfreq->total_trans++;

	}

	}

	devfreq->last_stat_updated = cur_time;





	return 0;

out:

	devfreq->last_stat_updated = cur_time;

	return ret;

}

}





/**

/**