Merge branch 'for-5.15-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

Pull workqueue fixes from Tejun Heo:
 "One patch to add a missing __printf annotation and the other to enable
  deferred printing for debug dumps to avoid deadlocks when triggered
  from some contexts (e.g. console drivers)"

* 'for-5.15-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: fix state-dump console deadlock
  workqueue: annotate alloc_workqueue() as printf

1 files changed, 16 insertions, 2 deletions

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 33a6b4a2443d..1b3eb1e9531f 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -4830,8 +4830,16 @@ void show_workqueue_state(void)
 
 		for_each_pwq(pwq, wq) {
 			raw_spin_lock_irqsave(&pwq->pool->lock, flags);
-			if (pwq->nr_active || !list_empty(&pwq->inactive_works))
+			if (pwq->nr_active || !list_empty(&pwq->inactive_works)) {
+				/*
+				 * Defer printing to avoid deadlocks in console
+				 * drivers that queue work while holding locks
+				 * also taken in their write paths.
+				 */
+				printk_deferred_enter();
 				show_pwq(pwq);
+				printk_deferred_exit();
+			}
 			raw_spin_unlock_irqrestore(&pwq->pool->lock, flags);
 			/*
 			 * We could be printing a lot from atomic context, e.g.
@@ -4849,7 +4857,12 @@ void show_workqueue_state(void)
 		raw_spin_lock_irqsave(&pool->lock, flags);
 		if (pool->nr_workers == pool->nr_idle)
 			goto next_pool;
-
+		/*
+		 * Defer printing to avoid deadlocks in console drivers that
+		 * queue work while holding locks also taken in their write
+		 * paths.
+		 */
+		printk_deferred_enter();
 		pr_info("pool %d:", pool->id);
 		pr_cont_pool_info(pool);
 		pr_cont(" hung=%us workers=%d",
@@ -4864,6 +4877,7 @@ void show_workqueue_state(void)
 			first = false;
 		}
 		pr_cont("\n");
+		printk_deferred_exit();
 	next_pool:
 		raw_spin_unlock_irqrestore(&pool->lock, flags);
 		/*