netdev - Re: [PATCH bpf] xdp: Reset prog in dev_change_xdp

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Date:   Tue, 14 Apr 2020 21:45:12 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Toke Høiland-Jørgensen <toke@...hat.com>,
        David Ahern <dsahern@...nel.org>, ast@...nel.org
Cc:     netdev@...r.kernel.org, David Ahern <dsahern@...il.com>
Subject: Re: [PATCH bpf] xdp: Reset prog in dev_change_xdp_fd when fd is
 negative

On 4/14/20 9:17 AM, Toke Høiland-Jørgensen wrote:
> David Ahern <dsahern@...nel.org> writes:
> 
>> From: David Ahern <dsahern@...il.com>
>>
>> The commit mentioned in the Fixes tag reuses the local prog variable
>> when looking up an expected_fd. The variable is not reset when fd < 0
>> causing a detach with the expected_fd set to actually call
>> dev_xdp_install for the existing program. The end result is that the
>> detach does not happen.
>>
>> Fixes: 92234c8f15c8 ("xdp: Support specifying expected existing program when attaching XDP")
>> Signed-off-by: David Ahern <dsahern@...il.com>
>> Cc: Toke Høiland-Jørgensen <toke@...hat.com>
> 
> Ugh, my bad (obviously!). Thanks for the fix! I'll send an update to the
> selftest to catch errors like this...

+1

> Reviewed-by: Toke Høiland-Jørgensen <toke@...hat.com>

Applied, thanks!