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workqueue: Detach workers directly in idle_cull_fn()

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The code to kick off the destruction of workers is now in a process
context (idle_cull_fn()), and the detaching of a worker is not required
to be inside the worker thread now, so just do the detaching directly
in idle_cull_fn().

wake_dying_workers() is renamed to detach_dying_workers() and the unneeded
wakeup in wake_dying_workers() is also removed.

Cc: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Lai Jiangshan 2024-06-21 15:32:24 +08:00 committed by Tejun Heo
parent f45b1c3c33
commit f4b7b53c94
1 changed files with 19 additions and 26 deletions
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45
kernel/workqueue.c
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@ -2695,6 +2695,16 @@ static void unbind_worker(struct worker *worker)
WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, cpu_possible_mask) < 0);
}
static void detach_worker(struct worker *worker)
{
lockdep_assert_held(&wq_pool_attach_mutex);
unbind_worker(worker);
list_del(&worker->node);
worker->pool = NULL;
}
/**
* worker_detach_from_pool() - detach a worker from its pool
* @worker: worker which is attached to its pool
@ -2711,11 +2721,7 @@ static void worker_detach_from_pool(struct worker *worker)
WARN_ON_ONCE(pool->flags & POOL_BH);
mutex_lock(&wq_pool_attach_mutex);
unbind_worker(worker);
list_del(&worker->node);
worker->pool = NULL;
detach_worker(worker);
mutex_unlock(&wq_pool_attach_mutex);
/* clear leftover flags without pool->lock after it is detached */
@ -2807,24 +2813,12 @@ fail:
return NULL;
}
static void wake_dying_workers(struct list_head *cull_list)
static void detach_dying_workers(struct list_head *cull_list)
{
struct worker *worker;
list_for_each_entry(worker, cull_list, entry) {
unbind_worker(worker);
/*
* If the worker was somehow already running, then it had to be
* in pool->idle_list when set_worker_dying() happened or we
* wouldn't have gotten here.
*
* Thus, the worker must either have observed the WORKER_DIE
* flag, or have set its state to TASK_IDLE. Either way, the
* below will be observed by the worker and is safe to do
* outside of pool->lock.
*/
wake_up_process(worker->task);
}
list_for_each_entry(worker, cull_list, entry)
detach_worker(worker);
}
static void reap_dying_workers(struct list_head *cull_list)
@ -2930,9 +2924,9 @@ static void idle_cull_fn(struct work_struct *work)
/*
* Grabbing wq_pool_attach_mutex here ensures an already-running worker
* cannot proceed beyong worker_detach_from_pool() in its self-destruct
* path. This is required as a previously-preempted worker could run after
* set_worker_dying() has happened but before wake_dying_workers() did.
* cannot proceed beyong set_pf_worker() in its self-destruct path.
* This is required as a previously-preempted worker could run after
* set_worker_dying() has happened but before detach_dying_workers() did.
*/
mutex_lock(&wq_pool_attach_mutex);
raw_spin_lock_irq(&pool->lock);
@ -2953,7 +2947,7 @@ static void idle_cull_fn(struct work_struct *work)
}
raw_spin_unlock_irq(&pool->lock);
wake_dying_workers(&cull_list);
detach_dying_workers(&cull_list);
mutex_unlock(&wq_pool_attach_mutex);
reap_dying_workers(&cull_list);
@ -3336,7 +3330,6 @@ woke_up:
set_task_comm(worker->task, "kworker/dying");
ida_free(&pool->worker_ida, worker->id);
worker_detach_from_pool(worker);
WARN_ON_ONCE(!list_empty(&worker->entry));
return 0;
}
@ -4921,7 +4914,7 @@ static void put_unbound_pool(struct worker_pool *pool)
WARN_ON(pool->nr_workers || pool->nr_idle);
raw_spin_unlock_irq(&pool->lock);
wake_dying_workers(&cull_list);
detach_dying_workers(&cull_list);
mutex_unlock(&wq_pool_attach_mutex);