linux-kernel - Re: [PATCH bpf-next 3/3] bpf/bpftool: handle libbpf_probe_prog

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Message-ID: <8457bd5f-0541-e128-b033-05131381c590@isovalent.com>
Date:   Fri, 1 Apr 2022 17:05:07 +0100
From:   Quentin Monnet <quentin@...valent.com>
To:     Milan Landaverde <milan@...verde.com>, bpf@...r.kernel.org
Cc:     ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
        kafai@...com, songliubraving@...com, yhs@...com,
        john.fastabend@...il.com, kpsingh@...nel.org,
        davemarchevsky@...com, sdf@...gle.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH bpf-next 3/3] bpf/bpftool: handle libbpf_probe_prog_type
 errors

2022-03-31 11:45 UTC-0400 ~ Milan Landaverde <milan@...verde.com>
> Previously [1], we were using bpf_probe_prog_type which returned a
> bool, but the new libbpf_probe_bpf_prog_type can return a negative
> error code on failure. This change decides for bpftool to declare
> a program type is not available on probe failure.
> 
> [1] https://lore.kernel.org/bpf/20220202225916.3313522-3-andrii@kernel.org/
> 
> Signed-off-by: Milan Landaverde <milan@...verde.com>
> ---
>  tools/bpf/bpftool/feature.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/bpf/bpftool/feature.c b/tools/bpf/bpftool/feature.c
> index c2f43a5d38e0..b2fbaa7a6b15 100644
> --- a/tools/bpf/bpftool/feature.c
> +++ b/tools/bpf/bpftool/feature.c
> @@ -564,7 +564,7 @@ probe_prog_type(enum bpf_prog_type prog_type, bool *supported_types,
>  
>  		res = probe_prog_type_ifindex(prog_type, ifindex);
>  	} else {
> -		res = libbpf_probe_bpf_prog_type(prog_type, NULL);
> +		res = libbpf_probe_bpf_prog_type(prog_type, NULL) > 0;
>  	}
>  
>  #ifdef USE_LIBCAP

Reviewed-by: Quentin Monnet <quentin@...valent.com>

Thanks!