From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet 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: Mon, 23 Feb 2015 11:51:51 -0800 Message-ID: <1424721111.5565.66.camel@edumazet-glaptop2.roam.corp.google.com> References: <1424713924-6821-2-git-send-email-eyal.birger@gmail.com> <1424713924-6821-4-git-send-email-eyal.birger@gmail.com> <20150223205633.7fbd08d4@halley> <1424718636.5565.58.camel@edumazet-glaptop2.roam.corp.google.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Shmulik Ladkani , David Miller , Eric Dumazet , netdev@vger.kernel.org To: Eyal Birger Return-path: Received: from mail-ig0-f176.google.com ([209.85.213.176]:64576 "EHLO mail-ig0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752234AbbBWTvy (ORCPT ); Mon, 23 Feb 2015 14:51:54 -0500 Received: by mail-ig0-f176.google.com with SMTP id hl2so21062292igb.3 for ; Mon, 23 Feb 2015 11:51:53 -0800 (PST) In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Mon, 2015-02-23 at 21:25 +0200, Eyal Birger wrote: > The original commit introducing dropcount for af_packet > (see http://marc.info/?l=linux-netdev&m=125450261121971) also claimed > the proper location would in fact be skb->cb[]. However, it was also > claimed that > skb->cb[] is all used up. > > Things are even more complicated now as dropcount became a socket > level feature and skb->cb[] is handled differently in each protocol family. I did a check, and all current sock_recv_ts_and_drops() users have room in skb->cb[] to store dropcount, say at the beginning of the array. I have no big opinion here, but intuitively dropcount has a very short lifetime and skb->cb[] seems appropriate.