PM / devfreq: Rewrite devfreq_update_status() to fix multiple bugs (e35d35a1) · Commits · 戴 / test

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:

Saravana Kannan <skannan@codeaurora.org> Signed-off-by:

MyungJoo Ham <myungjoo.ham@samsung.com>

drivers/devfreq/devfreq.c

+20 −11

Original line number	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)
		{
		int lev, prev_lev;
		int lev, prev_lev, ret = 0;
		unsigned long cur_time;

		lev = devfreq_get_freq_level(devfreq, freq);
		if (lev < 0)
		return lev;

		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;
		if (freq != devfreq->previous_freq) {
		prev_lev = devfreq_get_freq_level(devfreq,
		devfreq->previous_freq);

		lev = devfreq_get_freq_level(devfreq, freq);
		if (lev < 0) {
		ret = lev;
		goto out;
		}

		if (lev != prev_lev) {
		devfreq->trans_table[(prev_lev *
		devfreq->profile->max_state) + lev]++;
		devfreq->total_trans++;
		}
		devfreq->last_stat_updated = cur_time;

		return 0;
		out:
		devfreq->last_stat_updated = cur_time;
		return ret;
		}

		/**

Admin message