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
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 2ebef6b..74d3c1e 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -399,9 +399,8 @@
* RETURNS:
* Pointer to the allocated workqueue on success, %NULL on failure.
*/
-struct workqueue_struct *alloc_workqueue(const char *fmt,
- unsigned int flags,
- int max_active, ...);
+__printf(1, 4) struct workqueue_struct *
+alloc_workqueue(const char *fmt, unsigned int flags, int max_active, ...);
/**
* alloc_ordered_workqueue - allocate an ordered workqueue
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 33a6b4a..1b3eb1e 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -4830,8 +4830,16 @@
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 @@
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 @@
first = false;
}
pr_cont("\n");
+ printk_deferred_exit();
next_pool:
raw_spin_unlock_irqrestore(&pool->lock, flags);
/*
