diff options
| author | Oleg Nesterov <oleg@tv-sign.ru> | 2008-04-29 01:00:27 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-04-29 08:06:11 -0700 |
| commit | 00dfcaf748f46de89efe41baa298b5cf9adda67e (patch) | |
| tree | 4420dbfac9ba213e1604320cf9615a505ca909fd /kernel | |
| parent | 786083667e0ced85ce17c4c0b6c57a9f47c5b9f2 (diff) | |
workqueues: shrink cpu_populated_map when CPU dies
When cpu_populated_map was introduced, it was supposed that cwq->thread can
survive after CPU_DEAD, that is why we never shrink cpu_populated_map.
This is not very nice, we can safely remove the already dead CPU from the map.
The only required change is that destroy_workqueue() must hold the hotplug
lock until it destroys all cwq->thread's, to protect the cpu_populated_map.
We could make the local copy of cpu mask and drop the lock, but
sizeof(cpumask_t) may be very large.
Also, fix the comment near queue_work(). Unless _cpu_down() happens we do
guarantee the cpu-affinity of the work_struct, and we have users which rely on
this.
[akpm@linux-foundation.org: repair comment]
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/workqueue.c | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 00ff4d08e370..1ad0ee489cd1 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -158,8 +158,8 @@ static void __queue_work(struct cpu_workqueue_struct *cwq, * * Returns 0 if @work was already on a queue, non-zero otherwise. * - * We queue the work to the CPU it was submitted, but there is no - * guarantee that it will be processed by that CPU. + * We queue the work to the CPU on which it was submitted, but if the CPU dies + * it can be processed by another CPU. */ int queue_work(struct workqueue_struct *wq, struct work_struct *work) { @@ -815,12 +815,12 @@ void destroy_workqueue(struct workqueue_struct *wq) spin_lock(&workqueue_lock); list_del(&wq->list); spin_unlock(&workqueue_lock); - put_online_cpus(); for_each_cpu_mask(cpu, *cpu_map) { cwq = per_cpu_ptr(wq->cpu_wq, cpu); cleanup_workqueue_thread(cwq, cpu); } + put_online_cpus(); free_percpu(wq->cpu_wq); kfree(wq); @@ -838,7 +838,6 @@ static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, action &= ~CPU_TASKS_FROZEN; switch (action) { - case CPU_UP_PREPARE: cpu_set(cpu, cpu_populated_map); } @@ -866,6 +865,12 @@ static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, } } + switch (action) { + case CPU_UP_CANCELED: + case CPU_DEAD: + cpu_clear(cpu, cpu_populated_map); + } + return NOTIFY_OK; } |