workqueue: pick cwq instead of pool in __queue_work()
Currently, __queue_work() chooses the pool to queue a work item to and
then determines cwq from the target wq and the chosen pool. This is a
bit backwards in that we can determine cwq first and simply use
cwq->pool. This way, we can skip get_std_worker_pool() in queueing
path which will be a hurdle when implementing custom worker pools.
Update __queue_work() such that it chooses the target cwq and then use
cwq->pool instead of the other way around. While at it, add missing
{} in an if statement.
This patch doesn't introduce any functional changes.
tj: The original patch had two get_cwq() calls - the first to
determine the pool by doing get_cwq(cpu, wq)->pool and the second
to determine the matching cwq from get_cwq(pool->cpu, wq).
Updated the function such that it chooses cwq instead of pool and
removed the second call. Rewrote the description.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 1801c37..d6fdce1 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1193,8 +1193,6 @@
static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
struct work_struct *work)
{
- bool highpri = wq->flags & WQ_HIGHPRI;
- struct worker_pool *pool;
struct cpu_workqueue_struct *cwq;
struct list_head *worklist;
unsigned int work_flags;
@@ -1215,7 +1213,7 @@
WARN_ON_ONCE(!is_chained_work(wq)))
return;
- /* determine pool to use */
+ /* determine the cwq to use */
if (!(wq->flags & WQ_UNBOUND)) {
struct worker_pool *last_pool;
@@ -1228,37 +1226,36 @@
* work needs to be queued on that cpu to guarantee
* non-reentrancy.
*/
- pool = get_std_worker_pool(cpu, highpri);
+ cwq = get_cwq(cpu, wq);
last_pool = get_work_pool(work);
- if (last_pool && last_pool != pool) {
+ if (last_pool && last_pool != cwq->pool) {
struct worker *worker;
spin_lock(&last_pool->lock);
worker = find_worker_executing_work(last_pool, work);
- if (worker && worker->current_cwq->wq == wq)
- pool = last_pool;
- else {
+ if (worker && worker->current_cwq->wq == wq) {
+ cwq = get_cwq(last_pool->cpu, wq);
+ } else {
/* meh... not running there, queue here */
spin_unlock(&last_pool->lock);
- spin_lock(&pool->lock);
+ spin_lock(&cwq->pool->lock);
}
} else {
- spin_lock(&pool->lock);
+ spin_lock(&cwq->pool->lock);
}
} else {
- pool = get_std_worker_pool(WORK_CPU_UNBOUND, highpri);
- spin_lock(&pool->lock);
+ cwq = get_cwq(WORK_CPU_UNBOUND, wq);
+ spin_lock(&cwq->pool->lock);
}
- /* pool determined, get cwq and queue */
- cwq = get_cwq(pool->cpu, wq);
+ /* cwq determined, queue */
trace_workqueue_queue_work(req_cpu, cwq, work);
if (WARN_ON(!list_empty(&work->entry))) {
- spin_unlock(&pool->lock);
+ spin_unlock(&cwq->pool->lock);
return;
}
@@ -1276,7 +1273,7 @@
insert_work(cwq, work, worklist, work_flags);
- spin_unlock(&pool->lock);
+ spin_unlock(&cwq->pool->lock);
}
/**