diff options
| author | Todd Poynor <toddpoynor@google.com> | 2012-12-20 15:51:00 -0800 |
|---|---|---|
| committer | John Stultz <john.stultz@linaro.org> | 2016-02-16 13:52:50 -0800 |
| commit | 1dc7486fd81019314463d5077d8b4d13c41f3b34 (patch) | |
| tree | a4e32612ce288ec368f1e84fba2c8569aef6b9a6 /drivers | |
| parent | 583695f13bbcc33f356a3fe598c30b10bd0c5c48 (diff) | |
cpufreq: interactive: fix race on timer restart on governor start
Starting the governor, or restarting on a hotplugged-in CPU, can race
with the timer start in idle, triggering a BUG on timer already pending.
Start the timer before setting the enable flag, and use enable_sem to
protect the sequence (and ensure correct order of the update to the
enable flag). Delete any existing timer for safety.
Change-Id: Ife77cf9fe099e8fd8543224cbf148c6722c2ffb0
Reported-by: Francisco Franco <francisco.franco@cloudcar.com>
Signed-off-by: Todd Poynor <toddpoynor@google.com>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/cpufreq/cpufreq_interactive.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/cpufreq/cpufreq_interactive.c b/drivers/cpufreq/cpufreq_interactive.c index 74f56093d2f3..d22d162c9f27 100644 --- a/drivers/cpufreq/cpufreq_interactive.c +++ b/drivers/cpufreq/cpufreq_interactive.c @@ -919,17 +919,17 @@ static int cpufreq_governor_interactive(struct cpufreq_policy *policy, ktime_to_us(ktime_get()); pcpu->hispeed_validate_time = pcpu->floor_validate_time; - pcpu->governor_enabled = 1; - smp_wmb(); + down_write(&pcpu->enable_sem); expires = jiffies + usecs_to_jiffies(timer_rate); pcpu->cpu_timer.expires = expires; add_timer_on(&pcpu->cpu_timer, j); - if (timer_slack_val >= 0) { expires += usecs_to_jiffies(timer_slack_val); pcpu->cpu_slack_timer.expires = expires; add_timer_on(&pcpu->cpu_slack_timer, j); } + pcpu->governor_enabled = 1; + up_write(&pcpu->enable_sem); } /* |