linux-kernel - Re: [PATCH] tcp: fix error return code in tcp_xmit_probe

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Message-ID: <CANn89i+_GjNjjwAZU1VXG5OWFna3Vd1a6F-L7oYvNUObowzvuQ@mail.gmail.com>
Date:   Wed, 13 Apr 2022 19:15:24 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     Hongbin Wang <wh_bin@....com>
Cc:     David Miller <davem@...emloft.net>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        David Ahern <dsahern@...nel.org>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>, netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>, bpf <bpf@...r.kernel.org>
Subject: Re: [PATCH] tcp: fix error return code in tcp_xmit_probe_skb

On Wed, Apr 13, 2022 at 6:58 PM Hongbin Wang <wh_bin@....com> wrote:
>
> When alloc_skb failed, should return ENOMEM


Can you explain which rule mandates this statement ?

The only caller that propagates this error has other "return -1;"

The precise value of the error, we do not care, as long it is negative.

To be clear, this error code is not propagated to user space, so this
patch only adds code churn.


>
>
> Signed-off-by: Hongbin Wang <wh_bin@....com>
> ---
>  net/ipv4/tcp_output.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
> index c221f3bce975..b97c85814d9c 100644
> --- a/net/ipv4/tcp_output.c
> +++ b/net/ipv4/tcp_output.c
> @@ -3996,7 +3996,7 @@ static int tcp_xmit_probe_skb(struct sock *sk, int urgent, int mib)
>         skb = alloc_skb(MAX_TCP_HEADER,
>                         sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN));
>         if (!skb)
> -               return -1;
> +               return -ENOMEM;
>
>         /* Reserve space for headers and set control bits. */
>         skb_reserve(skb, MAX_TCP_HEADER);
> --
> 2.25.1
>