Re: [PATCH 2/2] usbnet: Fix a race between usbnet_stop() and the BH

From: Eugene Shatokhin <redacted>
Date: Mon, 24 Aug 2015 23:13:43 +0300

The race may happen when a device (e.g. YOTA 4G LTE Modem) is
unplugged while the system is downloading a large file from the Net.

Hardware breakpoints and Kprobes with delays were used to confirm that
the race does actually happen.

The race is on skb_queue ('next' pointer) between usbnet_stop()
and rx_complete(), which, in turn, calls usbnet_bh().

Here is a part of the call stack with the code where the changes to the
queue happen. The line numbers are for the kernel 4.1.0:

 ...

It looks like this patch needs more discussion/work.