From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net-next v3 0/7] net: move skb->dropcount to skb->cb[] Date: Mon, 02 Mar 2015 00:20:00 -0500 (EST) Message-ID: <20150302.002000.2074179681664043670.davem@davemloft.net> References: <1425214711-9562-1-git-send-email-eyal.birger@gmail.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: willemb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, edumazet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, shmulik.ladkani-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, linux-bluetooth-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, marcel-kz+m5ild9QBg9hUCZPvPmw@public.gmane.org, netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: eyal.birger-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org Return-path: In-Reply-To: <1425214711-9562-1-git-send-email-eyal.birger-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Sender: linux-bluetooth-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: netdev.vger.kernel.org From: Eyal Birger Date: Sun, 1 Mar 2015 14:58:24 +0200 > Commit 977750076d98 ("af_packet: add interframe drop cmsg (v6)") > unionized skb->mark and skb->dropcount in order to allow recording > of the socket drop count while maintaining struct sk_buff size. > > skb->dropcount was introduced since there was no available room > in skb->cb[] in packet sockets. However, its introduction led to > the inability to export skb->mark to userspace. > > It was considered to alias skb->priority instead of skb->mark. > However, that would lead to the inabilty to export skb->priority > to userspace if desired. Such change may also lead to hard-to-find > issues as skb->priority is assumed to be alias free, and, as noted > by Shmulik Ladkani, is not 'naturally orthogonal' with other skb > fields. > > This patch series follows the suggestions made by Eric Dumazet moving > the dropcount metric to skb->cb[], eliminating this problem > at the expense of 4 bytes less in skb->cb[] for protocol families > using it. > > The patch series include compactization of bluetooth and packet > use of skb->cb[] as well as the infrastructure for placing dropcount > in skb->cb[]. Ok, I think I can live with this. Series applied, thanks.