netdev - Re: how to use skb_postpush

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Message-ID: <0ccfa6d0e8b982c9c64ca3de913b0142c58317f1.camel@sipsolutions.net>
Date:   Tue, 21 Apr 2020 18:54:15 +0200
From:   Johannes Berg <johannes@...solutions.net>
To:     netdev@...r.kernel.org
Cc:     linux-wireless@...r.kernel.org
Subject: Re: how to use skb_postpush_rcsum()?

On Tue, 2020-04-21 at 17:20 +0200, Johannes Berg wrote:
> Hi,
> 
> This is probably a stupid question but I'm hitting my head against the
> wall ...
> 
> I have an skb. I have this:
> 
> 
>         if (skb->ip_summed == CHECKSUM_COMPLETE) {
>                 printk(KERN_DEBUG "csum before\n");
>                 printk(KERN_DEBUG "  hw = 0x%.4x\n", skb->csum);
>                 printk(KERN_DEBUG "  sw = 0x%.4x\n", csum_fold(skb_checksum(skb, 0, skb->len, 0)));

Never mind. The csum_fold() there is obviously the problem - that
shouldn't match, it should match the folded skb->csum. I have a missing
~ basically.

johannes