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From: Eyal Birger <eyal.birger@gmail.com>
To: Willem de Bruijn <willemb@google.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
	David Miller <davem@davemloft.net>,
	Shmulik Ladkani <shmulik.ladkani@gmail.com>,
	Eric Dumazet <edumazet@google.com>,
	Network Development <netdev@vger.kernel.org>
Subject: Re: [PATCH net-next v3 3/4] net: use skb->priority for overloading skb->dropcount and skb->reserved_tailroom instead of skb->mark
Date: Wed, 25 Feb 2015 23:15:14 +0200	[thread overview]
Message-ID: <CAHsH6GtW1d9PvaOuTPxWqK_dWVZHxY7j7qgSJ8sChYsVYFj2UQ@mail.gmail.com> (raw)
In-Reply-To: <CA+FuTScV8AgEumMsPnVVmRkYKjbJYLigAqqhrgzx9DDsXDz=2w@mail.gmail.com>

On Wed, Feb 25, 2015 at 10:49 PM, Willem de Bruijn <willemb@google.com> wrote:
>>> We have to be a bit creative/hacky to keep skb size small.
>>>
>>
>> I agree. I don't think these feature deserve an skb size increase, so
>> some hackery is required.
>>
>> Though, as skb->cb[] is somewhat 'owned' by the protocol families on
>> socket enqueue
>> I tend to find aliasing skb->priority with skb->dropcount "a lesser
>> evil" as compared with
>> partitioning the skb->cb[] space.
>
> Please consider another field than priority. There are use
> cases that want to receive priority, similar to reading mark.
>
> Indeed, I have a draft packet auxdata patch for one user who wants
> to see the iptables changes (and infer tc effects) on egress packets.
> Fwiw, that patch also exposes mark, and runs into exactly this issue
> that you're fixing, so thanks :)
>
> Fields that are consistently NULL on enqueue, such as the dev field
> that Eric proposed, do not have this drawback.

Thanks! I was wondering whether someone would want to fetch skb->priority.

I had already conceded that aliasing skb->priority won't hold.

I plan to submit a patch series for moving skb->dropcount to skb->cb[].
Following that I will re-submit the patch for fetching skb->mark in auxdata.

  reply	other threads:[~2015-02-25 21:15 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-02-23 17:52 [PATCH net-next v3 1/4] net: Rename sock_recv_ts_and_drops() to sock_cmsg_recv() Eyal Birger
2015-02-23 17:52 ` [PATCH net-next v3 2/4] ipv4,v6: avoid setting skb->priority when skb->reserved_tailroom is in use in igmpv3/mld Eyal Birger
2015-02-23 17:52 ` [PATCH net-next v3 3/4] net: use skb->priority for overloading skb->dropcount and skb->reserved_tailroom instead of skb->mark Eyal Birger
2015-02-23 18:56   ` Shmulik Ladkani
2015-02-23 19:10     ` Eric Dumazet
2015-02-23 19:25       ` Eyal Birger
2015-02-23 19:51         ` Eric Dumazet
2015-02-23 21:48     ` David Miller
2015-02-24  6:58       ` Eyal Birger
2015-02-24 10:10         ` Eyal Birger
2015-02-24 13:18           ` Eric Dumazet
2015-02-24 14:07             ` Eyal Birger
2015-02-24 14:25               ` Eric Dumazet
2015-02-24 14:41                 ` Eyal Birger
2015-02-24 14:41               ` Eric Dumazet
2015-02-24 15:24                 ` Eyal Birger
2015-02-25 20:49                   ` Willem de Bruijn
2015-02-25 21:15                     ` Eyal Birger [this message]
2015-02-25 14:10               ` Eyal Birger
2015-02-25 16:50                 ` Eric Dumazet
2015-02-23 17:52 ` [PATCH net-next v3 4/4] net: Introducing socket mark receive socket option Eyal Birger

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