usbip: keep usbip_device sockfd state in sync with tcp_socket

BugLink: http://bugs.launchpad.net/bugs/1756866

commit 009f41ae upstream.

Keep usbip_device sockfd state in sync with tcp_socket. When tcp_socket
is reset to null, reset sockfd to -1 to keep it in sync.
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

drivers/usb/usbip/stub_dev.c

@@ -87,6 +87,7 @@ static ssize_t store_sockfd(struct device *dev, struct device_attribute *attr,
 			goto err;
 
 		sdev->ud.tcp_socket = socket;
+		sdev->ud.sockfd = sockfd;
 
 		spin_unlock_irq(&sdev->ud.lock);
 
@@ -186,6 +187,7 @@ static void stub_shutdown_connection(struct usbip_device *ud)
 	if (ud->tcp_socket) {
 		sockfd_put(ud->tcp_socket);
 		ud->tcp_socket = NULL;
+		ud->sockfd = -1;
 	}
 
 	/* 3. free used data */
@@ -280,6 +282,7 @@ static struct stub_device *stub_device_alloc(struct usb_device *udev)
 	sdev->ud.status		= SDEV_ST_AVAILABLE;
 	spin_lock_init(&sdev->ud.lock);
 	sdev->ud.tcp_socket	= NULL;
+	sdev->ud.sockfd		= -1;
 
 	INIT_LIST_HEAD(&sdev->priv_init);
 	INIT_LIST_HEAD(&sdev->priv_tx);

drivers/usb/usbip/vhci_hcd.c

@@ -797,6 +797,7 @@ static void vhci_shutdown_connection(struct usbip_device *ud)
 	if (vdev->ud.tcp_socket) {
 		sockfd_put(vdev->ud.tcp_socket);
 		vdev->ud.tcp_socket = NULL;
+		vdev->ud.sockfd = -1;
 	}
 	pr_info("release socket\n");
 
@@ -844,6 +845,7 @@ static void vhci_device_reset(struct usbip_device *ud)
 	if (ud->tcp_socket) {
 		sockfd_put(ud->tcp_socket);
 		ud->tcp_socket = NULL;
+		ud->sockfd = -1;
 	}
 	ud->status = VDEV_ST_NULL;