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| author | Tejun Heo <tj@kernel.org> | 2013-03-12 11:30:04 -0700 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2013-03-12 11:30:04 -0700 |
| commit | 8719dceae2f98a578507c0f6b49c93f320bd729c (patch) | |
| tree | 3132f4c6ed84ec893bcad3aaec230fa78cede95d | |
| parent | 618b01eb426dd2d73a4b5e5ebc6379e4eee3b123 (diff) | |
| download | op-kernel-dev-8719dceae2f98a578507c0f6b49c93f320bd729c.zip op-kernel-dev-8719dceae2f98a578507c0f6b49c93f320bd729c.tar.gz | |
workqueue: reject adjusting max_active or applying attrs to ordered workqueues
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>
| -rw-r--r-- | include/linux/workqueue.h | 3 | ||||
| -rw-r--r-- | kernel/workqueue.c | 9 |
2 files changed, 11 insertions, 1 deletions
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index 1751ec4..5668ab2 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -295,6 +295,7 @@ enum { WQ_CPU_INTENSIVE = 1 << 5, /* cpu instensive workqueue */ __WQ_DRAINING = 1 << 16, /* internal: workqueue is draining */ + __WQ_ORDERED = 1 << 17, /* internal: workqueue is ordered */ WQ_MAX_ACTIVE = 512, /* I like 512, better ideas? */ WQ_MAX_UNBOUND_PER_CPU = 4, /* 4 * #cpus for unbound wq */ @@ -397,7 +398,7 @@ __alloc_workqueue_key(const char *fmt, unsigned int flags, int max_active, * Pointer to the allocated workqueue on success, %NULL on failure. */ #define alloc_ordered_workqueue(fmt, flags, args...) \ - alloc_workqueue(fmt, WQ_UNBOUND | (flags), 1, ##args) + alloc_workqueue(fmt, WQ_UNBOUND | __WQ_ORDERED | (flags), 1, ##args) #define create_workqueue(name) \ alloc_workqueue((name), WQ_MEM_RECLAIM, 1) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 590f4d04..cecd4ff 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -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); |
