workqueue.c: Increase workqueue name length

[ Upstream commit 31c89007285d365aa36f71d8fb0701581c770a27 ]

Currently we limit the size of the workqueue name to 24 characters due to
commit ecf6881 ("workqueue: make workqueue->name[] fixed len")
Increase the size to 32 characters and print a warning in the event
the requested name is larger than the limit of 32 characters.

Signed-off-by: Audra Mitchell <audra@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Stable-dep-of: 5797b1c18919 ("workqueue: Implement system-wide nr_active enforcement for unbound workqueues")
Signed-off-by: Sasha Levin <sashal@kernel.org>

kernel/workqueue.c

@@ -108,7 +108,7 @@ enum {
 	RESCUER_NICE_LEVEL	= MIN_NICE,
 	HIGHPRI_NICE_LEVEL	= MIN_NICE,
 
-	WQ_NAME_LEN		= 24,
+	WQ_NAME_LEN		= 32,
 };
 
 /*
@@ -4673,6 +4673,7 @@ struct workqueue_struct *alloc_workqueue(const char *fmt,
 	va_list args;
 	struct workqueue_struct *wq;
 	struct pool_workqueue *pwq;
+	int len;
 
 	/*
 	 * Unbound && max_active == 1 used to imply ordered, which is no longer
@@ -4699,9 +4700,12 @@ struct workqueue_struct *alloc_workqueue(const char *fmt,
 	}
 
 	va_start(args, max_active);
-	vsnprintf(wq->name, sizeof(wq->name), fmt, args);
+	len = vsnprintf(wq->name, sizeof(wq->name), fmt, args);
 	va_end(args);
 
+	if (len >= WQ_NAME_LEN)
+		pr_warn_once("workqueue: name exceeds WQ_NAME_LEN. Truncating to: %s\n", wq->name);
+
 	max_active = max_active ?: WQ_DFL_ACTIVE;
 	max_active = wq_clamp_max_active(max_active, flags, wq->name);