Commit 509b3204 authored by Daniel Jordan's avatar Daniel Jordan Committed by Herbert Xu
Browse files

workqueue: require CPU hotplug read exclusion for apply_workqueue_attrs 



Change the calling convention for apply_workqueue_attrs to require CPU
hotplug read exclusion.

Avoids lockdep complaints about nested calls to get_online_cpus in a
future patch where padata calls apply_workqueue_attrs when changing
other CPU-hotplug-sensitive data structures with the CPU read lock
already held.

Signed-off-by: default avatarDaniel Jordan <daniel.m.jordan@oracle.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarSteffen Klassert <steffen.klassert@secunet.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-crypto@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 513c98d0

kernel/workqueue.c

+14 −5
Original line number Diff line number Diff line
@@ -4030,6 +4030,8 @@ static int apply_workqueue_attrs_locked(struct workqueue_struct *wq, 
 *

 * Performs GFP_KERNEL allocations.

 *

 * Assumes caller has CPU hotplug read exclusion, i.e. get_online_cpus().

 *

 * Return: 0 on success and -errno on failure.

 */

int apply_workqueue_attrs(struct workqueue_struct *wq,
@@ -4037,9 +4039,11 @@ int apply_workqueue_attrs(struct workqueue_struct *wq, 
{

	int ret;



	apply_wqattrs_lock();

	lockdep_assert_cpus_held();



	mutex_lock(&wq_pool_mutex);

	ret = apply_workqueue_attrs_locked(wq, attrs);

	apply_wqattrs_unlock();

	mutex_unlock(&wq_pool_mutex);



	return ret;

}
@@ -4152,16 +4156,21 @@ static int alloc_and_link_pwqs(struct workqueue_struct *wq) 
			mutex_unlock(&wq->mutex);

		}

		return 0;

	} else if (wq->flags & __WQ_ORDERED) {

	}



	get_online_cpus();

	if (wq->flags & __WQ_ORDERED) {

		ret = apply_workqueue_attrs(wq, ordered_wq_attrs[highpri]);

		/* there should only be single pwq for ordering guarantee */

		WARN(!ret && (wq->pwqs.next != &wq->dfl_pwq->pwqs_node ||

			      wq->pwqs.prev != &wq->dfl_pwq->pwqs_node),

		     "ordering guarantee broken for workqueue %s\n", wq->name);

		return ret;

	} else {

		return apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]);

		ret = apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]);

	}

	put_online_cpus();



	return ret;

}



static int wq_clamp_max_active(int max_active, unsigned int flags,