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authorLeonard Crestez <leonard.crestez@nxp.com>2019-09-24 10:52:23 +0300
committerChanwoo Choi <cw00.choi@samsung.com>2019-11-06 12:04:00 +0900
commit2abb0d5268ae7b5ddf82099b1f8d5aa8414637d4 (patch)
tree3c6991f0a3e90ac554a58d23bcfd6cddb14928bf /drivers/devfreq/devfreq.c
parentd68adc8f85cd757bd33c8d7b2660ad6f16f7f3dc (diff)
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: 39688ce6facd ("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>
Diffstat (limited to 'drivers/devfreq/devfreq.c')
-rw-r--r--drivers/devfreq/devfreq.c12
1 files changed, 9 insertions, 3 deletions
diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 60859a2400bc..d6c3dce9e9d5 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -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++)