diff options
| -rw-r--r-- | include/linux/workqueue.h | 1 | ||||
| -rw-r--r-- | kernel/workqueue.c | 32 |
2 files changed, 30 insertions, 3 deletions
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index 0a7814131e6..07cf5e5f91c 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -225,6 +225,7 @@ static inline unsigned int work_static(struct work_struct *work) { return 0; } enum { WQ_FREEZEABLE = 1 << 0, /* freeze during suspend */ WQ_SINGLE_CPU = 1 << 1, /* only single cpu at a time */ + WQ_NON_REENTRANT = 1 << 2, /* guarantee non-reentrance */ }; extern struct workqueue_struct * diff --git a/kernel/workqueue.c b/kernel/workqueue.c index c68277c204a..bce1074bdec 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -534,11 +534,37 @@ static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, debug_work_activate(work); - /* determine gcwq to use */ + /* + * Determine gcwq to use. SINGLE_CPU is inherently + * NON_REENTRANT, so test it first. + */ if (!(wq->flags & WQ_SINGLE_CPU)) { - /* just use the requested cpu for multicpu workqueues */ + struct global_cwq *last_gcwq; + + /* + * It's multi cpu. If @wq is non-reentrant and @work + * was previously on a different cpu, it might still + * be running there, in which case the work needs to + * be queued on that cpu to guarantee non-reentrance. + */ gcwq = get_gcwq(cpu); - spin_lock_irqsave(&gcwq->lock, flags); + if (wq->flags & WQ_NON_REENTRANT && + (last_gcwq = get_work_gcwq(work)) && last_gcwq != gcwq) { + struct worker *worker; + + spin_lock_irqsave(&last_gcwq->lock, flags); + + worker = find_worker_executing_work(last_gcwq, work); + + if (worker && worker->current_cwq->wq == wq) + gcwq = last_gcwq; + else { + /* meh... not running there, queue here */ + spin_unlock_irqrestore(&last_gcwq->lock, flags); + spin_lock_irqsave(&gcwq->lock, flags); + } + } else + spin_lock_irqsave(&gcwq->lock, flags); } else { unsigned int req_cpu = cpu; |