WQ_RESCUER is superflous. WQ_MEM_RECLAIM indicates that the user wants a rescuer and testing wq->rescuer for NULL can answer whether a given workqueue has a rescuer or not. Drop WQ_RESCUER and test wq->rescuer directly.
This will help simplifying __alloc_workqueue_key() failure path by allowing it to use destroy_workqueue() on a partially constructed workqueue, which in turn will help implementing dynamic management of pool_workqueues. While at it, clear wq->rescuer after freeing it in destroy_workqueue(). This is a precaution as scheduled changes will make destruction more complex. This patch doesn't introduce any functional changes. Signed-off-by: Tejun Heo <t...@kernel.org> --- include/linux/workqueue.h | 1 - kernel/workqueue.c | 22 ++++++++++------------ 2 files changed, 10 insertions(+), 13 deletions(-) diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index 2683e8e..0341403 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -294,7 +294,6 @@ enum { WQ_CPU_INTENSIVE = 1 << 5, /* cpu instensive workqueue */ WQ_DRAINING = 1 << 6, /* internal: workqueue is draining */ - WQ_RESCUER = 1 << 7, /* internal: workqueue has rescuer */ WQ_MAX_ACTIVE = 512, /* I like 512, better ideas? */ WQ_MAX_UNBOUND_PER_CPU = 4, /* 4 * #cpus for unbound wq */ diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 1695bd6..bcc02bb 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -1825,7 +1825,7 @@ static void send_mayday(struct work_struct *work) lockdep_assert_held(&workqueue_lock); - if (!(wq->flags & WQ_RESCUER)) + if (!wq->rescuer) return; /* mayday mayday mayday */ @@ -2283,7 +2283,7 @@ sleep: * @__rescuer: self * * Workqueue rescuer thread function. There's one rescuer for each - * workqueue which has WQ_RESCUER set. + * workqueue which has WQ_MEM_RECLAIM set. * * Regular work processing on a pool may block trying to create a new * worker which uses GFP_KERNEL allocation which has slight chance of @@ -2767,7 +2767,7 @@ static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr) * flusher is not running on the same workqueue by verifying write * access. */ - if (pwq->wq->saved_max_active == 1 || pwq->wq->flags & WQ_RESCUER) + if (pwq->wq->saved_max_active == 1 || pwq->wq->rescuer) lock_map_acquire(&pwq->wq->lockdep_map); else lock_map_acquire_read(&pwq->wq->lockdep_map); @@ -3405,13 +3405,6 @@ struct workqueue_struct *__alloc_workqueue_key(const char *fmt, va_end(args); va_end(args1); - /* - * Workqueues which may be used during memory reclaim should - * have a rescuer to guarantee forward progress. - */ - if (flags & WQ_MEM_RECLAIM) - flags |= WQ_RESCUER; - max_active = max_active ?: WQ_DFL_ACTIVE; max_active = wq_clamp_max_active(max_active, flags, wq->name); @@ -3442,7 +3435,11 @@ struct workqueue_struct *__alloc_workqueue_key(const char *fmt, } local_irq_enable(); - if (flags & WQ_RESCUER) { + /* + * Workqueues which may be used during memory reclaim should + * have a rescuer to guarantee forward progress. + */ + if (flags & WQ_MEM_RECLAIM) { struct worker *rescuer; wq->rescuer = rescuer = alloc_worker(); @@ -3526,9 +3523,10 @@ void destroy_workqueue(struct workqueue_struct *wq) spin_unlock_irq(&workqueue_lock); - if (wq->flags & WQ_RESCUER) { + if (wq->rescuer) { kthread_stop(wq->rescuer->task); kfree(wq->rescuer); + wq->rescuer = NULL; } /* -- 1.8.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/