netdev - Re: [PATCH net-next] skbuff: only inherit relevant tx

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Date:   Thu, 08 Jun 2017 09:20:32 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc:     netdev@...r.kernel.org, davem@...emloft.net, soheil@...gle.com,
        Willem de Bruijn <willemb@...gle.com>
Subject: Re: [PATCH net-next] skbuff: only inherit relevant tx_flags

On Thu, 2017-06-08 at 11:35 -0400, Willem de Bruijn wrote:
> From: Willem de Bruijn <willemb@...gle.com>
> 
> When inheriting tx_flags from one skbuff to another, always apply a
> mask to avoid overwriting unrelated other bits in the field.
> 
> The two SKBTX_SHARED_FRAG cases clears all other bits. In practice,
> tx_flags are zero at this point now. But this is fragile. Timestamp
> flags are set, for instance, if in tcp_gso_segment, after this clear
> in skb_segment.
> 
> The SKBTX_ANY_TSTAMP mask in __skb_tstamp_tx ensures that new
> skbs do not accidentally inherit flags such as SKBTX_SHARED_FRAG.
> 
> Signed-off-by: Willem de Bruijn <willemb@...gle.com>


Acked-by: Eric Dumazet <edumazet@...gle.com>