Re: [PATCH bpf-next v3 6/6] selftests/bpf: fix file descriptor assertion in open_tuntap helper

[Willem de Bruijn <willemdebruijn.kernel@gmail.com>]

Marcus Wichelmann wrote:
> The open_tuntap helper function uses open() to get a file descriptor for
> /dev/net/tun.
> 
> The open(2) manpage writes this about its return value:
> 
>   On success, open(), openat(), and creat() return the new file
>   descriptor (a nonnegative integer).  On error, -1 is returned and
>   errno is set to indicate the error.
> 
> This means that the fd > 0 assertion in the open_tuntap helper is
> incorrect and should rather check for fd >= 0.
> 
> When running the BPF selftests locally, this incorrect assertion was not
> an issue, but the BPF kernel-patches CI failed because of this:
> 
>   open_tuntap:FAIL:open(/dev/net/tun) unexpected open(/dev/net/tun):
>   actual 0 <= expected 0
> 
> Signed-off-by: Marcus Wichelmann <marcus.wichelmann@hetzner-cloud.de>

Reviewed-by: Willem de Bruijn <willemb@google.com>