Hi Chris, > On 04/11/2017 04:33 PM, Christian Gromm wrote: > Well, this sounds like a workaround to me as you are changing the timing > by waiting for the URBs to finish. This might prevent the > race from happening. > I personally would rate it rather as a fix than as a workaround, because the "usb_wait_anchor_empty_timeout()" function doesn't only change the timing: It ensures that we won't kill any URB which is just being processed. And this is exactly the failure that we are observing here.
> I thought an USB device driver is allowed to kill anchored URBs at any > time, isn't it? > Both functions are described in Documentation/usb/anchors.txt and I agree: It is not stated clearly that we must always call the "usb_wait_anchor_empty_timeout()" function before we can call the "usb_kill_anchored_urbs()" function. Probably Oliver Neukum, who has written these functions long time ago, can explain shortly, if we can call the "usb_kill_anchored_urbs()" function always - and if not, in which situation the "usb_wait_anchor_empty_timeout()" function has to be called in advance. Kind regards, Rolf -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
