While freezing takes place globally, its execution is per-workqueue;
however, the current implementation makes use of the per-worker_pool
POOL_FREEZING flag. While it's not broken, the flag makes the code
more confusing and complicates freeze_workqueues_begin() and
thaw_workqueues() by requiring them to walk through all pools.
So we remove the POOL_FREEZING and use workqueue_freezing instead.
Signed-off-by: Lai Jiangshan <la...@cn.fujitsu.com>
---
kernel/workqueue.c | 32 +++++++-------------------------
1 files changed, 7 insertions(+), 25 deletions(-)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 98b38b5..a87de61 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -69,7 +69,6 @@ enum {
* worker_attach_to_pool() is in progress.
*/
POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */
- POOL_FREEZING = 1 << 3, /* freeze in progress */
/* worker flags */
WORKER_DIE = 1 << 1, /* die die die */
@@ -3532,9 +3531,6 @@ static struct worker_pool *get_unbound_pool(const struct
workqueue_attrs *attrs)
if (!pool || init_worker_pool(pool) < 0)
goto fail;
- if (workqueue_freezing)
- pool->flags |= POOL_FREEZING;
-
lockdep_set_subclass(&pool->lock, 1); /* see put_pwq() */
copy_workqueue_attrs(pool->attrs, attrs);
@@ -3641,7 +3637,12 @@ static void pwq_adjust_max_active(struct pool_workqueue
*pwq)
spin_lock_irq(&pwq->pool->lock);
- if (!freezable || !(pwq->pool->flags & POOL_FREEZING)) {
+ /*
+ * pwq_adjust_max_active() is invoked at least once
+ * after workqueue_freezing is changed, so it can fetch
+ * the workqueue_freezing without wq_pool_mutex held.
+ */
+ if (!freezable || !workqueue_freezing) {
pwq->max_active = wq->saved_max_active;
while (!list_empty(&pwq->delayed_works) &&
@@ -4750,24 +4751,14 @@ EXPORT_SYMBOL_GPL(work_on_cpu);
*/
void freeze_workqueues_begin(void)
{
- struct worker_pool *pool;
struct workqueue_struct *wq;
struct pool_workqueue *pwq;
- int pi;
mutex_lock(&wq_pool_mutex);
WARN_ON_ONCE(workqueue_freezing);
workqueue_freezing = true;
- /* set FREEZING */
- for_each_pool(pool, pi) {
- spin_lock_irq(&pool->lock);
- WARN_ON_ONCE(pool->flags & POOL_FREEZING);
- pool->flags |= POOL_FREEZING;
- spin_unlock_irq(&pool->lock);
- }
-
list_for_each_entry(wq, &workqueues, list) {
mutex_lock(&wq->mutex);
for_each_pwq(pwq, wq)
@@ -4837,21 +4828,13 @@ void thaw_workqueues(void)
{
struct workqueue_struct *wq;
struct pool_workqueue *pwq;
- struct worker_pool *pool;
- int pi;
mutex_lock(&wq_pool_mutex);
if (!workqueue_freezing)
goto out_unlock;
- /* clear FREEZING */
- for_each_pool(pool, pi) {
- spin_lock_irq(&pool->lock);
- WARN_ON_ONCE(!(pool->flags & POOL_FREEZING));
- pool->flags &= ~POOL_FREEZING;
- spin_unlock_irq(&pool->lock);
- }
+ workqueue_freezing = false;
/* restore max_active and repopulate worklist */
list_for_each_entry(wq, &workqueues, list) {
@@ -4861,7 +4844,6 @@ void thaw_workqueues(void)
mutex_unlock(&wq->mutex);
}
- workqueue_freezing = false;
out_unlock:
mutex_unlock(&wq_pool_mutex);
}
--
1.7.4.4
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