linux-kernel - [PATCH 5/6] workqueue: Use swait for wq_manager

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Date:   Thu, 13 Jun 2019 16:50:26 +0200
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     linux-kernel@...r.kernel.org
Cc:     Tejun Heo <tj@...nel.org>, Lai Jiangshan <jiangshanlai@...il.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH 5/6] workqueue: Use swait for wq_manager_wait

In order for the workqueue code use raw_spinlock_t typed locking there
must not be a spinlock_t typed lock be acquired. A wait_queue_head uses
a spinlock_t lock for its list protection.

Use a swait based queue head to avoid raw_spinlock_t -> spinlock_t
locking.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 kernel/workqueue.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index a3c2959e5c4f0..f27a57fce5079 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -50,6 +50,7 @@
 #include <linux/uaccess.h>
 #include <linux/sched/isolation.h>
 #include <linux/nmi.h>
+#include <linux/swait.h>
 
 #include "workqueue_internal.h"
 
@@ -301,7 +302,7 @@ static struct workqueue_attrs *wq_update_unbound_numa_attrs_buf;
 static DEFINE_MUTEX(wq_pool_mutex);	/* protects pools and workqueues list */
 static DEFINE_MUTEX(wq_pool_attach_mutex); /* protects worker attach/detach */
 static DEFINE_SPINLOCK(wq_mayday_lock);	/* protects wq->maydays list */
-static DECLARE_WAIT_QUEUE_HEAD(wq_manager_wait); /* wait for manager to go away */
+static DECLARE_SWAIT_QUEUE_HEAD(wq_manager_wait); /* wait for manager to go away */
 
 static LIST_HEAD(workqueues);		/* PR: list of all workqueues */
 static bool workqueue_freezing;		/* PL: have wqs started freezing? */
@@ -2143,7 +2144,7 @@ static bool manage_workers(struct worker *worker)
 
 	pool->manager = NULL;
 	pool->flags &= ~POOL_MANAGER_ACTIVE;
-	wake_up(&wq_manager_wait);
+	swake_up_one(&wq_manager_wait);
 	return true;
 }
 
@@ -3538,7 +3539,7 @@ static void put_unbound_pool(struct worker_pool *pool)
 	 * manager and @pool gets freed with the flag set.
 	 */
 	spin_lock_irq(&pool->lock);
-	wait_event_lock_irq(wq_manager_wait,
+	swait_event_lock_irq(wq_manager_wait,
 			    !(pool->flags & POOL_MANAGER_ACTIVE), pool->lock);
 	pool->flags |= POOL_MANAGER_ACTIVE;
 
-- 
2.20.1