On Mon, Dec 18, 2006 at 01:34:16AM +0300, Oleg Nesterov wrote:
> void fastcall flush_workqueue(struct workqueue_struct *wq)
> {
> - might_sleep();
> -
> + mutex_lock(&workqueue_mutex);
> if (is_single_threaded(wq)) {
> /* Always use first cpu's area. */
> - flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, singlethread_cpu),
> - -1);
> + flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, singlethread_cpu));
> } else {
> int cpu;
>
> - mutex_lock(&workqueue_mutex);
> for_each_online_cpu(cpu)
Can compiler optimizations lead to cpu_online_map being cached in a register
while running this loop? AFAICS cpu_online_map is not declared to be
volatile. If it can be cached, then we have the danger of invoking
flush_cpu_workqueue() on a dead cpu (because flush_cpu_workqueue drops
workqueue_mutex, cpu hp events can change cpu_online_map while we are in
flush_cpu_workqueue).
> - flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, cpu), cpu);
> - mutex_unlock(&workqueue_mutex);
> + flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, cpu));
--
Regards,
vatsa
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