netdev - Re: [PATCH] Revert "net: pskb_trim_rcsum() and CHECKSUM

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Message-ID: <87o9g8geu0.fsf@igel.home>
Date:   Mon, 18 Jun 2018 19:54:47 +0200
From:   Andreas Schwab <schwab@...ux-m68k.org>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     Mathieu Malaterre <malat@...ian.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Christophe LEROY <christophe.leroy@....fr>,
        Meelis Roos <mroos@...ux.ee>, netdev@...r.kernel.org,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH] Revert "net: pskb_trim_rcsum() and CHECKSUM_COMPLETE are friends"

On Jun 17 2018, Eric Dumazet <eric.dumazet@...il.com> wrote:

> Oh this is silly, please try :
>
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index c642304f178ce0a4e1358d59e45032a39f76fb3f..54dd9c18ecad817812898d6f335e1794a07dabbe 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -1845,10 +1845,9 @@ EXPORT_SYMBOL(___pskb_trim);
>  int pskb_trim_rcsum_slow(struct sk_buff *skb, unsigned int len)
>  {
>         if (skb->ip_summed == CHECKSUM_COMPLETE) {
> -               int delta = skb->len - len;
> +               __wsum csumdiff = skb_checksum(skb, len, skb->len - len, 0);
>  
> -               skb->csum = csum_sub(skb->csum,
> -                                    skb_checksum(skb, len, delta, 0));
> +               skb->csum = csum_block_sub(skb->csum, csumdiff, len);
>         }
>         return __pskb_trim(skb, len);
>  }

That doesn't help either.

Andreas.

-- 
Andreas Schwab, schwab@...ux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
"And now for something completely different."