wonderful-mobile/exynos-linux-stable
2
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

workqueue: reject adjusting max_active or applying attrs to ordered workqueues

Browse source 
Adjusting max_active of or applying new workqueue_attrs to an ordered
workqueue breaks its ordering guarantee.  The former is obvious.  The
latter is because applying attrs creates a new pwq (pool_workqueue)
and there is no ordering constraint between the old and new pwqs.

Make apply_workqueue_attrs() and workqueue_set_max_active() trigger
WARN_ON() if those operations are requested on an ordered workqueue
and fail / ignore respectively.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
This commit is contained in:
Tejun Heo 2013-03-12 11:30:04 -07:00
parent 618b01eb42
commit 8719dceae2
2 changed files with 11 additions and 1 deletions
Download patch file Download diff file Expand all files Collapse all files

9
kernel/workqueue.c
View file

@ -3494,9 +3494,14 @@ int apply_workqueue_attrs(struct workqueue_struct *wq,
struct pool_workqueue *pwq, *last_pwq;
struct worker_pool *pool;
/* only unbound workqueues can change attributes */
if (WARN_ON(!(wq->flags & WQ_UNBOUND)))
return -EINVAL;
/* creating multiple pwqs breaks ordering guarantee */
if (WARN_ON((wq->flags & __WQ_ORDERED) && !list_empty(&wq->pwqs)))
return -EINVAL;
pwq = kmem_cache_zalloc(pwq_cache, GFP_KERNEL);
if (!pwq)
return -ENOMEM;
@ -3752,6 +3757,10 @@ void workqueue_set_max_active(struct workqueue_struct *wq, int max_active)
{
struct pool_workqueue *pwq;
/* disallow meddling with max_active for ordered workqueues */
if (WARN_ON(wq->flags & __WQ_ORDERED))
return;
max_active = wq_clamp_max_active(max_active, wq->flags, wq->name);
spin_lock_irq(&workqueue_lock);