[PATCH 6.18.y 1/2] workqueue: release pwq pools by pool type

[Sasha Levin <sashal@kernel.org>]

From: Breno Leitao <leitao@debian.org>

[ Upstream commit 3180ee71b676845603274c66f6bb5528939cf470 ]

Add is_percpu_pool() and test the pool directly for per cpu. Convert the
other open-coded pool->cpu checks -- in put_unbound_pool(),
pool_allowed_cpus() and the workqueue watchdog -- to the same helper.

No functional change.

Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>

Use a single-evaluation macro for the pool predicate. Keep the existing
watchdog timestamp and reporting behavior, converting only its pool-type
test; the newer stall-duration accounting is absent.

Stable-dep-of: cf9c8aaea0d4 ("workqueue: Fix unbound pool lifetime for pending pwqs")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 kernel/workqueue.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index fff53beae69b1..b7b09a618d047 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1562,6 +1562,9 @@ work_func_t wq_worker_last_func(struct task_struct *task)
 	return worker->last_func;
 }
 
+/* True if @pool is a static per-cpu pool rather than an unbound one. */
+#define is_percpu_pool(pool) ((pool)->cpu >= 0)
+
 /**
  * wq_node_nr_active - Determine wq_node_nr_active to use
  * @wq: workqueue of interest
@@ -2689,7 +2692,7 @@ static struct worker *alloc_worker(int node)
 
 static cpumask_t *pool_allowed_cpus(struct worker_pool *pool)
 {
-	if (pool->cpu < 0 && pool->attrs->affn_strict)
+	if (!is_percpu_pool(pool) && pool->attrs->affn_strict)
 		return pool->attrs->__pod_cpumask;
 	else
 		return pool->attrs->cpumask;
@@ -5030,7 +5033,7 @@ static void put_unbound_pool(struct worker_pool *pool)
 		return;
 
 	/* sanity checks */
-	if (WARN_ON(!(pool->cpu < 0)) ||
+	if (WARN_ON(is_percpu_pool(pool)) ||
 	    WARN_ON(!list_empty(&pool->worklist)))
 		return;
 
@@ -5182,7 +5185,7 @@ static void pwq_release_workfn(struct kthread_work *work)
 		mutex_unlock(&wq->mutex);
 	}
 
-	if (wq->flags & WQ_UNBOUND) {
+	if (!is_percpu_pool(pool)) {
 		mutex_lock(&wq_pool_mutex);
 		put_unbound_pool(pool);
 		mutex_unlock(&wq_pool_mutex);
@@ -7720,7 +7723,7 @@ static void wq_watchdog_timer_fn(struct timer_list *unused)
 		/* did we stall? */
 		if (time_after(now, ts + thresh)) {
 			lockup_detected = true;
-			if (pool->cpu >= 0 && !(pool->flags & POOL_BH)) {
+			if (is_percpu_pool(pool) && !(pool->flags & POOL_BH)) {
 				pool->cpu_stall = true;
 				cpu_pool_stall = true;
 			}
-- 
2.53.0