netdev - Re: [PATCH] gso: Validate assumption of frag

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Date:   Mon, 17 Apr 2017 15:32:59 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     ilant@...lanox.com
Cc:     netdev@...r.kernel.org, alexander.h.duyck@...el.com,
        eric.dumazet@...il.com, steffen.klassert@...unet.com,
        borisp@...lanox.com, ilyal@...lanox.com
Subject: Re: [PATCH] gso: Validate assumption of frag_list segementation

From: <ilant@...lanox.com>
Date: Sun, 16 Apr 2017 11:00:07 +0300

> From: Ilan Tayari <ilant@...lanox.com>
> 
> Commit 07b26c9454a2 ("gso: Support partial splitting at the frag_list
> pointer") assumes that all SKBs in a frag_list (except maybe the last
> one) contain the same amount of GSO payload.
> 
> This assumption is not always correct, resulting in the following
> warning message in the log:
>     skb_segment: too many frags
> 
> For example, mlx5 driver in Striding RQ mode creates some RX SKBs with
> one frag, and some with 2 frags.
> After GRO, the frag_list SKBs end up having different amounts of payload.
> If this frag_list SKB is then forwarded, the aforementioned assumption
> is violated.
> 
> Validate the assumption, and fall back to software GSO if it not true.
> 
> Fixes: 07b26c9454a2 ("gso: Support partial splitting at the frag_list pointer")
> Signed-off-by: Ilan Tayari <ilant@...lanox.com>
> Signed-off-by: Ilya Lesokhin <ilyal@...lanox.com>
> ---

Your commit message mentions a fixes tag which make this change seem
relevant for 'net', but your patch depends upon things in 'net-next'
and therefore only applies there.

I've added this change to net-next, but I want an explanation of why
this change is not targettting 'net' if it seems to fix a problem
there.

Thanks.