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

From: David Miller
Date: Tue Aug 25 2015 - 22:45:14 EST


From: Eugene Shatokhin <eugene.shatokhin@xxxxxxxxxx>
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.

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