linux-kernel - [PATCH -mm 3/3] nbd: don't abuse irqsave/irqrestore while taking nbd->tasks

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Date:	Sun, 25 Oct 2015 16:26:41 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Markus Pargmann <mpa@...gutronix.de>
Cc:	nbd-general@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Subject: [PATCH -mm 3/3] nbd: don't abuse irqsave/irqrestore while taking
	nbd->tasks_lock

Both nbd_thread_recv() and nbd_thread_send() are might_sleep() and
called with irqs enabled(), irqsave/irqrestore make no sense and imo
look confusing.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 drivers/block/nbd.c |   22 ++++++++++------------
 1 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 0ffd73c..fd79405 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -406,23 +406,22 @@ static int nbd_thread_recv(struct nbd_device *nbd)
 {
 	struct request *req;
 	int ret;
-	unsigned long flags;
 
 	BUG_ON(nbd->magic != NBD_MAGIC);
 
 	sk_set_memalloc(nbd->sock->sk);
 
-	spin_lock_irqsave(&nbd->tasks_lock, flags);
+	spin_lock_irq(&nbd->tasks_lock);
 	nbd->task_recv = current;
-	spin_unlock_irqrestore(&nbd->tasks_lock, flags);
+	spin_unlock_irq(&nbd->tasks_lock);
 
 	ret = device_create_file(disk_to_dev(nbd->disk), &pid_attr);
 	if (ret) {
 		dev_err(disk_to_dev(nbd->disk), "device_create_file failed!\n");
 
-		spin_lock_irqsave(&nbd->tasks_lock, flags);
+		spin_lock_irq(&nbd->tasks_lock);
 		nbd->task_recv = NULL;
-		spin_unlock_irqrestore(&nbd->tasks_lock, flags);
+		spin_unlock_irq(&nbd->tasks_lock);
 
 		return ret;
 	}
@@ -439,9 +438,9 @@ static int nbd_thread_recv(struct nbd_device *nbd)
 
 	device_remove_file(disk_to_dev(nbd->disk), &pid_attr);
 
-	spin_lock_irqsave(&nbd->tasks_lock, flags);
+	spin_lock_irq(&nbd->tasks_lock);
 	nbd->task_recv = NULL;
-	spin_unlock_irqrestore(&nbd->tasks_lock, flags);
+	spin_unlock_irq(&nbd->tasks_lock);
 
 	if (signal_pending(current)) {
 		dev_warn(nbd_to_dev(nbd), "pid %d, %s, got signal",
@@ -543,11 +542,10 @@ static int nbd_thread_send(void *data)
 {
 	struct nbd_device *nbd = data;
 	struct request *req;
-	unsigned long flags;
 
-	spin_lock_irqsave(&nbd->tasks_lock, flags);
+	spin_lock_irq(&nbd->tasks_lock);
 	nbd->task_send = current;
-	spin_unlock_irqrestore(&nbd->tasks_lock, flags);
+	spin_unlock_irq(&nbd->tasks_lock);
 
 	set_user_nice(current, MIN_NICE);
 	while (!kthread_should_stop() || !list_empty(&nbd->waiting_queue)) {
@@ -581,9 +579,9 @@ static int nbd_thread_send(void *data)
 		nbd_handle_req(nbd, req);
 	}
 
-	spin_lock_irqsave(&nbd->tasks_lock, flags);
+	spin_lock_irq(&nbd->tasks_lock);
 	nbd->task_send = NULL;
-	spin_unlock_irqrestore(&nbd->tasks_lock, flags);
+	spin_unlock_irq(&nbd->tasks_lock);
 
 	return 0;
 }
-- 
1.5.5.1

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