We have this plan for manage_workers(): if failed to grab
manager_mutex via mutex_trylock(), we will release gcwq->lock and then
grab manager_mutex again.
This plan will open a hole: hotplug is running after we release gcwq->lock,
and it will not handle the binding of manager. so we add ->manager
on worker_pool and let hotplug code(gcwq_unbind_fn()) handle it.
also fix too_many_workers() to use this pointer.
Signed-off-by: Lai Jiangshan <la...@cn.fujitsu.com>
---
kernel/workqueue.c | 12 ++++++++++--
1 files changed, 10 insertions(+), 2 deletions(-)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 3dd7ce2..b203806 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -165,6 +165,7 @@ struct worker_pool {
struct timer_list idle_timer; /* L: worker idle timeout */
struct timer_list mayday_timer; /* L: SOS timer for workers */
+ struct worker *manager; /* L: manager worker */
struct mutex manager_mutex; /* mutex manager should hold */
struct ida worker_ida; /* L: for worker IDs */
};
@@ -680,7 +681,7 @@ static bool need_to_manage_workers(struct worker_pool *pool)
/* Do we have too many workers and should some go away? */
static bool too_many_workers(struct worker_pool *pool)
{
- bool managing = mutex_is_locked(&pool->manager_mutex);
+ bool managing = !!pool->manager;
int nr_idle = pool->nr_idle + managing; /* manager is considered idle */
int nr_busy = pool->nr_workers - nr_idle;
@@ -2066,6 +2067,7 @@ static bool manage_workers(struct worker *worker)
if (!mutex_trylock(&pool->manager_mutex))
return ret;
+ pool->manager = worker;
pool->flags &= ~POOL_MANAGE_WORKERS;
/*
@@ -2076,6 +2078,8 @@ static bool manage_workers(struct worker *worker)
ret |= maybe_create_worker(pool);
mutex_unlock(&pool->manager_mutex);
+ pool->manager = NULL;
+
return ret;
}
@@ -3438,9 +3442,12 @@ static void gcwq_unbind_fn(struct work_struct *work)
* ones which are still executing works from before the last CPU
* down must be on the cpu. After this, they may become diasporas.
*/
- for_each_worker_pool(pool, gcwq)
+ for_each_worker_pool(pool, gcwq) {
list_for_each_entry(worker, &pool->idle_list, entry)
worker->flags |= WORKER_UNBOUND;
+ if (pool->manager)
+ pool->manager->flags |= WORKER_UNBOUND;
+ }
for_each_busy_worker(worker, i, pos, gcwq)
worker->flags |= WORKER_UNBOUND;
@@ -3760,6 +3767,7 @@ static int __init init_workqueues(void)
setup_timer(&pool->mayday_timer, gcwq_mayday_timeout,
(unsigned long)pool);
+ pool->manager = NULL;
mutex_init(&pool->manager_mutex);
ida_init(&pool->worker_ida);
}
--
1.7.4.4
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