On Wed, 2009-05-27 at 11:25 -0400, Alan Stern wrote:
> This patch (as1244) fixes a crash in usb-serial that occurs when a
> sub-driver returns a positive value from its attach method, indicating
> that new firmware was loaded and the device will disconnect and
> reconnect. The usb-serial core then skips the step of registering the
> port devices; when the disconnect occurs, the attempt to unregister
> the ports fails dramatically.
Greg, dramatically means Oops btw :-)
It could be some changes in the device layer that made it choke on
those device_del calls to a NULLed out struct device while it may
not have before. I think the bug started in 2.6.29. I jumped straight
from .28 to .30-rc on the machine that I use the keyspan on when I
noticed it, then quickly try a .29 built I had around and off the top of
my mind, it happened there too.
Cheers,
Ben.
> This problem shows up with Keyspan devices and it might affect others
> as well.
>
> When the attach method returns a positive value, the patch sets
> num_ports to 0. This tells usb_serial_disconnect() not to try
> unregistering any of the ports; instead they are cleaned up by
> destroy_serial().
>
> Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> Tested-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
>
> ---
>
> It looks like this problem has existed ever since the serial bus was
> introduced. I don't know nobody complained about it until now. It
> isn't related to the other usb-serial changes made recently.
>
> Alan Stern
>
>
> Index: usb-2.6/drivers/usb/serial/usb-serial.c
> ===================================================================
> --- usb-2.6.orig/drivers/usb/serial/usb-serial.c
> +++ usb-2.6/drivers/usb/serial/usb-serial.c
> @@ -974,6 +974,7 @@ int usb_serial_probe(struct usb_interfac
> if (retval > 0) {
> /* quietly accept this device, but don't bind to a
> serial port as it's about to disappear */
> + serial->num_ports = 0;
> goto exit;
> }
> }
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