linux-kernel - Re: [PATCH v2 bpf] tools: bpftool: Add missing close before bpftool net attach exit

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Date:   Wed, 11 Nov 2020 00:44:15 -0800
From:   John Fastabend <john.fastabend@...il.com>
To:     "wanghai (M)" <wanghai38@...wei.com>,
        John Fastabend <john.fastabend@...il.com>
Cc:     quentin@...valent.com, mrostecki@...nsuse.org, ast@...nel.org,
        daniel@...earbox.net, kafai@...com, songliubraving@...com,
        yhs@...com, andrii@...nel.org, kpsingh@...omium.org,
        toke@...hat.com, danieltimlee@...il.com, bpf@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 bpf] tools: bpftool: Add missing close before bpftool
 net attach exit

wanghai (M) wrote:
> 
> 在 2020/11/10 12:33, John Fastabend 写道:
> > Wang Hai wrote:
> >> progfd is created by prog_parse_fd(), before 'bpftool net attach' exit,
> >> it should be closed.
> >>
> >> Fixes: 04949ccc273e ("tools: bpftool: add net attach command to attach XDP on interface")
> >> Signed-off-by: Wang Hai <wanghai38@...wei.com>
> >> ---

[...]

> > Alternatively we could add an 'err = 0' here, but above should never
> > return a value >0 as far as I can see.
> It's true that 'err > 0' doesn't exist currently , but adding 'err = 0' 
> would make the code clearer. Thanks for your advice.
> >> +cleanup:
> >> +	close(progfd);
> >> +	return err;
> >>   }
> >>   
> >>   static int do_detach(int argc, char **argv)
> >> -- 
> >> 2.17.1
> >>
> Can it be fixed like this?
> 
> --- a/tools/bpf/bpftool/net.c
> +++ b/tools/bpf/bpftool/net.c
> @@ -578,8 +578,8 @@ static int do_attach(int argc, char **argv)
> 
>          ifindex = net_parse_dev(&argc, &argv);
>          if (ifindex < 1) {
> -               close(progfd);
> -               return -EINVAL;
> +               err = -EINVAL;
> +               goto cleanup;
>          }
> 
>          if (argc) {
> @@ -587,8 +587,8 @@ static int do_attach(int argc, char **argv)
>                          overwrite = true;
>                  } else {
>                          p_err("expected 'overwrite', got: '%s'?", *argv);
> -                       close(progfd);
> -                       return -EINVAL;
> +                       err = -EINVAL;
> +                       goto cleanup;
>                  }
>          }
> 
> @@ -597,16 +597,19 @@ static int do_attach(int argc, char **argv)
>                  err = do_attach_detach_xdp(progfd, attach_type, ifindex,
>                                             overwrite);
> 
> -       if (err < 0) {
> +       if (err) {
>                  p_err("interface %s attach failed: %s",
>                        attach_type_strings[attach_type], strerror(-err));
> -               return err;
> +               goto cleanup;
>          }
> 
>          if (json_output)
>                  jsonw_null(json_wtr);
> 
> -       return 0;
> +       ret = 0;
> +cleanup:
> +       close(progfd);
> +       return err;
>   }
> 

LGTM. Send a v3.