On Tuesday, December 08, 2015 12:29:05 PM Viresh Kumar wrote:
On 08-12-15, 01:39, Rafael J. Wysocki wrote:
@@ -269,9 +259,6 @@ static void dbs_timer_handler(unsigned l { struct cpu_dbs_info *cdbs = (struct cpu_dbs_info *)data; struct cpu_common_dbs_info *shared = cdbs->shared;
- unsigned long flags;
- spin_lock_irqsave(&shared->timer_lock, flags);
/* * Timer handler isn't allowed to queue work at the moment, because: @@ -279,12 +266,10 @@ static void dbs_timer_handler(unsigned l * - We are stopping the governor * - Or we are updating the sampling rate of ondemand governor */
- if (!shared->skip_work) {
shared->skip_work++;
- if (atomic_inc_return(&shared->skip_work) > 1)
atomic_dec(&shared->skip_work);- else queue_work(system_wq, &shared->work);
- }
As explained in the other email, this is wrong..
OK, but instead of relying on the spinlock to wait for the already running dbs_timer_handler() in gov_cancel_work() (which is really easy to overlook and should at least be mentioned in a comment) we can wait for it explicitly.
That is, if the relevant code in gov_cancel_work() is like this:
atomic_inc(&shared->skip_work); gov_cancel_timers(shared->policy); cancel_work_sync(&shared->work); gov_cancel_timers(shared->policy); atomic_set(&shared->skip_work, 0);
then the work item should not be leaked behind the cancel_work_sync() any more AFAICS.
Thanks, Rafael