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authorTejun Heo <tj@kernel.org>2013-03-12 11:30:03 -0700
committerTejun Heo <tj@kernel.org>2013-03-12 11:30:03 -0700
commit493008a8e475771a2126e0ce95a73e35b371d277 (patch)
tree0e67b51ade42bb623456aa186cec7a5722a8420c
parentac6104cdf87cc162b0a0d78280d1dcb9752e25bb (diff)
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workqueue: drop WQ_RESCUER and test workqueue->rescuer for NULL instead
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 <tj@kernel.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
-rw-r--r--include/linux/workqueue.h1
-rw-r--r--kernel/workqueue.c22
2 files changed, 10 insertions, 13 deletions
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 00c1b9ba8252..c270b4eedf16 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -295,7 +295,6 @@ 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 a8b86f7b6e34..7ff2b9c5cc3a 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1827,7 +1827,7 @@ 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 */
@@ -2285,7 +2285,7 @@ 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
@@ -2769,7 +2769,7 @@ 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);
@@ -3412,13 +3412,6 @@ 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);
@@ -3449,7 +3442,11 @@ 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();
@@ -3533,9 +3530,10 @@ 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;
}
/*