[PATCH] ax88179_178a: don't send commands to detached device

[PATCH] ax88179_178a: don't send commands to detached device

[Emil Goode]

The .stop and .unbind callbacks of struct driver_info are
called even after a DETACH hot-plug event. In the case of
the ax88179_178a minidriver we need to make sure we are not
trying to send commands to a device that has been detached.
This leads to failure messages like below.

ax88179_178a 1-1.3:1.0 (unregistered net_device):
	Failed to write reg index 0x0001: -19

Signed-off-by: Emil Goode <emilgoode@gmail.com>
---
 drivers/net/usb/ax88179_178a.c |    6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/usb/ax88179_178a.c b/drivers/net/usb/ax88179_178a.c
index 054e59c..fe20ca8 100644
--- a/drivers/net/usb/ax88179_178a.c
+++ b/drivers/net/usb/ax88179_178a.c
@@ -1074,6 +1074,9 @@ static void ax88179_unbind(struct usbnet *dev, struct usb_interface *intf)
 {
 	u16 tmp16;
 
+	if (dev->udev->state == USB_STATE_NOTATTACHED)
+		return;
+
 	/* Configure RX control register => stop operation */
 	tmp16 = AX_RX_CTL_STOP;
 	ax88179_write_cmd(dev, AX_ACCESS_MAC, AX_RX_CTL, 2, 2, &tmp16);
@@ -1352,6 +1355,9 @@ static int ax88179_stop(struct usbnet *dev)
 {
 	u16 tmp16;
 
+	if (dev->udev->state == USB_STATE_NOTATTACHED)
+		return 0;
+
 	ax88179_read_cmd(dev, AX_ACCESS_MAC, AX_MEDIUM_STATUS_MODE,
 			 2, 2, &tmp16);
 	tmp16 &= ~AX_MEDIUM_RECEIVE_EN;
-- 
1.7.10.4

Re: [PATCH] ax88179_178a: don't send commands to detached device

[Alan Stern]

On Wed, 14 May 2014, Emil Goode wrote:

> The .stop and .unbind callbacks of struct driver_info are
> called even after a DETACH hot-plug event. In the case of
> the ax88179_178a minidriver we need to make sure we are not
> trying to send commands to a device that has been detached.
> This leads to failure messages like below.
> 
> ax88179_178a 1-1.3:1.0 (unregistered net_device):
> 	Failed to write reg index 0x0001: -19

Most driver don't bother to do this.  A few error messages in the log 
when a device gets unplugged are harmless.  Besides, this won't help 
with errors that occur between the time the device is unplugged and the 
time when the unbind callback runs.

Alan Stern