linux-kernel - [PATCH] nbd: Move socket shutdown out of spinlock

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Date:	Thu, 12 May 2016 11:43:15 +0200
From:	Markus Pargmann <mpa@...gutronix.de>
To:	"Pranay Kr . Srivastava" <pranjas@...il.com>
Cc:	nbd-general@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
	gregkh@...uxfoundation.org, Markus Pargmann <mpa@...gutronix.de>
Subject: [PATCH] nbd: Move socket shutdown out of spinlock

spinlocked ranges should be small and not contain calls into huge
subfunctions. Fix my mistake and just get the pointer to the socket
instead of doing everything with spinlock held.

Reported-by: Mikulas Patocka <mikulas@...bright.com>
Signed-off-by: Markus Pargmann <mpa@...gutronix.de>
---
 drivers/block/nbd.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 0b892eed06a0..157bf3da876e 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -173,20 +173,22 @@ static void nbd_end_request(struct nbd_device *nbd, struct request *req)
  */
 static void sock_shutdown(struct nbd_device *nbd)
 {
+	struct socket *sock;
+
 	spin_lock_irq(&nbd->sock_lock);
+	sock = nbd->sock;
+	nbd->sock = NULL;
+	spin_unlock_irq(&nbd->sock_lock);
 
-	if (!nbd->sock) {
-		spin_unlock_irq(&nbd->sock_lock);
+	if (!sock)
 		return;
-	}
+
+	del_timer(&nbd->timeout_timer);
 
 	dev_warn(disk_to_dev(nbd->disk), "shutting down socket\n");
-	kernel_sock_shutdown(nbd->sock, SHUT_RDWR);
-	sockfd_put(nbd->sock);
-	nbd->sock = NULL;
-	spin_unlock_irq(&nbd->sock_lock);
+	kernel_sock_shutdown(sock, SHUT_RDWR);
+	sockfd_put(sock);
 
-	del_timer(&nbd->timeout_timer);
 }
 
 static void nbd_xmit_timeout(unsigned long arg)
-- 
2.8.0.rc3