From: Todd Poynor <[email protected]> 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 <[email protected]> Signed-off-by: Todd Poynor <[email protected]> Signed-off-by: Bálint Czobor <[email protected]> --- drivers/cpufreq/cpufreq_interactive.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/cpufreq/cpufreq_interactive.c b/drivers/cpufreq/cpufreq_interactive.c index 74f5609..d22d162 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); } /* -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
