From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-1?Q?Nicolas_de_Peslo=FCan?= Subject: Re: [patch net-next-2.6 V3] net: convert bonding to use rx_handler Date: Sat, 19 Feb 2011 21:27:37 +0100 Message-ID: <4D6027B9.6050108@gmail.com> References: <4D5E8655.5070304@trash.net> <20110218145850.GF2939@psychotron.redhat.com> <20110218.120656.104048936.davem@davemloft.net> <20110218205832.GE2602@psychotron.redhat.com> <21593.1298070371@death> <20110219080523.GB2782@psychotron.redhat.com> <4D5FA1D7.4050801@gmail.com> <20110219110830.GD2782@psychotron.redhat.com> <20110219112842.GE2782@psychotron.redhat.com> <4D5FC308.9020507@gmail.com> <20110219134645.GF2782@psychotron.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Jay Vosburgh , David Miller , kaber@trash.net, eric.dumazet@gmail.com, netdev@vger.kernel.org, shemminger@linux-foundation.org, andy@greyhouse.net To: Jiri Pirko Return-path: Received: from mail-fx0-f46.google.com ([209.85.161.46]:52231 "EHLO mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751307Ab1BSU1n (ORCPT ); Sat, 19 Feb 2011 15:27:43 -0500 Received: by fxm17 with SMTP id 17so318400fxm.19 for ; Sat, 19 Feb 2011 12:27:41 -0800 (PST) In-Reply-To: <20110219134645.GF2782@psychotron.redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: Le 19/02/2011 14:46, Jiri Pirko a =E9crit : > Sat, Feb 19, 2011 at 02:18:00PM CET, nicolas.2p.debian@gmail.com wrot= e: >> Le 19/02/2011 12:28, Jiri Pirko a =E9crit : >>> Sat, Feb 19, 2011 at 12:08:31PM CET, jpirko@redhat.com wrote: >>>> Sat, Feb 19, 2011 at 11:56:23AM CET, nicolas.2p.debian@gmail.com w= rote: >>>>> Le 19/02/2011 09:05, Jiri Pirko a =E9crit : >>>>>> This patch converts bonding to use rx_handler. Results in cleane= r >>>>>> __netif_receive_skb() with much less exceptions needed. Also >>>>>> bond-specific work is moved into bond code. >>>>>> >>>>>> Signed-off-by: Jiri Pirko >>>>>> >>>>>> v1->v2: >>>>>> using skb_iif instead of new input_dev to remember orig= inal >>>>>> device >>>>>> v2->v3: >>>>>> set orig_dev =3D skb->dev if skb_iif is set >>>>>> >>>>> >>>>> Why do we need to let the rx_handlers call netif_rx() or __netif_= receive_skb()? >>>>> >>>>> Bonding used to be handled with very few overhead, simply replaci= ng >>>>> skb->dev with skb->dev->master. Time has passed and we eventually >>>>> added many special processing for bonding into __netif_receive_sk= b(), >>>>> but the overhead remained very light. >>>>> >>>>> Calling netif_rx() (or __netif_receive_skb()) to allow nesting wo= uld probably lead to some overhead. >>>>> >>>>> Can't we, instead, loop inside __netif_receive_skb(), and deliver >>>>> whatever need to be delivered, to whoever need, inside the loop ? >>>>> >>>>> rx_handler =3D rcu_dereference(skb->dev->rx_handler); >>>>> while (rx_handler) { >>>>> /* ... */ >>>>> orig_dev =3D skb->dev; >>>>> skb =3D rx_handler(skb); >>>>> /* ... */ >>>>> rx_handler =3D (skb->dev !=3D orig_dev) ? rcu_dereference(skb->d= ev->rx_handler) : NULL; >>>>> } >>>>> >>>>> This would reduce the overhead, while still allowing nesting: vla= n on >>>>> top on bonding, bridge on top on bonding, ... >>>> >>>> I see your point. Makes sense to me. But the loop would have to in= clude >>>> at least processing of ptype_all too. I'm going to cook a follow-u= p >>>> patch. >>>> >>> >>> DRAFT (doesn't modify rx_handlers): >>> >>> diff --git a/net/core/dev.c b/net/core/dev.c >>> index 4ebf7fe..e5dba47 100644 >>> --- a/net/core/dev.c >>> +++ b/net/core/dev.c >>> @@ -3115,6 +3115,7 @@ static int __netif_receive_skb(struct sk_buff= *skb) >>> { >>> struct packet_type *ptype, *pt_prev; >>> rx_handler_func_t *rx_handler; >>> + struct net_device *dev; >>> struct net_device *orig_dev; >>> struct net_device *null_or_dev; >>> int ret =3D NET_RX_DROP; >>> @@ -3129,7 +3130,9 @@ static int __netif_receive_skb(struct sk_buff= *skb) >>> if (netpoll_receive_skb(skb)) >>> return NET_RX_DROP; >>> >>> - __this_cpu_inc(softnet_data.processed); >>> + skb->skb_iif =3D skb->dev->ifindex; >>> + orig_dev =3D skb->dev; >> >> orig_dev should be set inside the loop, to reflect "previously >> crossed device", while following the path: >> >> eth0 -> bond0 -> br0. >> >> First step inside loop: >> >> orig_dev =3D eth0 >> skb->dev =3D bond0 (at the end of the loop). >> >> Second step inside loop: >> >> orig_dev =3D bond0 >> skb->dev =3D br0 (et the end of the loop). >> >> This would allow for exact match delivery to bond0 if someone bind t= here. >> >>> + >>> skb_reset_network_header(skb); >>> skb_reset_transport_header(skb); >>> skb->mac_len =3D skb->network_header - skb->mac_header; >>> @@ -3138,12 +3141,9 @@ static int __netif_receive_skb(struct sk_buf= f *skb) >>> >>> rcu_read_lock(); >>> >>> - if (!skb->skb_iif) { >>> - skb->skb_iif =3D skb->dev->ifindex; >>> - orig_dev =3D skb->dev; >>> - } else { >>> - orig_dev =3D dev_get_by_index_rcu(dev_net(skb->dev), skb->skb_ii= f); >>> - } >> >> I like the fact that it removes the above part. >> >>> +another_round: >>> + __this_cpu_inc(softnet_data.processed); >>> + dev =3D skb->dev; >>> >>> #ifdef CONFIG_NET_CLS_ACT >>> if (skb->tc_verd& TC_NCLS) { >>> @@ -3153,7 +3153,7 @@ static int __netif_receive_skb(struct sk_buff= *skb) >>> #endif >>> >>> list_for_each_entry_rcu(ptype,&ptype_all, list) { >>> - if (!ptype->dev || ptype->dev =3D=3D skb->dev) { >>> + if (!ptype->dev || ptype->dev =3D=3D dev) { >>> if (pt_prev) >>> ret =3D deliver_skb(skb, pt_prev, orig_dev); >>> pt_prev =3D ptype; >> >> Inside the loop, we should only do exact match delivery, for >> &ptype_all and for&ptype_base[ntohs(type)& PTYPE_HASH_MASK]: >> >> list_for_each_entry_rcu(ptype,&ptype_all, list) { >> - if (!ptype->dev || ptype->dev =3D=3D dev) { >> + if (ptype->dev =3D=3D dev) { >> if (pt_prev) >> ret =3D deliver_skb(skb, pt_prev, or= ig_dev); >> pt_prev =3D ptype; >> } >> } >> >> >> list_for_each_entry_rcu(ptype, >> &ptype_base[ntohs(type)& PTYPE_HASH_MASK], = list) { >> if (ptype->type =3D=3D type&& >> - (ptype->dev =3D=3D null_or_dev || ptype->dev =3D= =3D skb->dev)) { >> + (ptype->dev =3D=3D skb->dev)) { >> if (pt_prev) >> ret =3D deliver_skb(skb, pt_prev, or= ig_dev); >> pt_prev =3D ptype; >> } >> } >> >> After leaving the loop, we can do wilcard delivery, if skb is not NU= LL. >> >> list_for_each_entry_rcu(ptype,&ptype_all, list) { >> - if (!ptype->dev || ptype->dev =3D=3D dev) { >> + if (!ptype->dev) { >> if (pt_prev) >> ret =3D deliver_skb(skb, pt_prev, or= ig_dev); >> pt_prev =3D ptype; >> } >> } >> >> >> list_for_each_entry_rcu(ptype, >> &ptype_base[ntohs(type)& PTYPE_HASH_MASK], = list) { >> - if (ptype->type =3D=3D type&& >> - (ptype->dev =3D=3D null_or_dev || ptype->dev =3D= =3D skb->dev)) { >> + if (ptype->type =3D=3D type&& !ptype->dev) { >> if (pt_prev) >> ret =3D deliver_skb(skb, pt_prev, or= ig_dev); >> pt_prev =3D ptype; >> } >> } >> >> This would reduce the number of tests inside the >> list_for_each_entry_rcu() loops. And because we match only ptype->de= v >> =3D=3D dev inside the loop and !ptype->dev outside the loop, this sh= ould >> avoid duplicate delivery. > > Would you care to put this into patch so I can see the whole picture? > Thanks. Here is what I have in mind. It is based on your previous DRAFT patch, = and don't modify rx_handlers yet. Only compile tested !! I don't know if every pieces are at the right place. I wonder what to d= o with CONFIG_NET_CLS_ACT=20 part, that currently is between ptype_all and ptype_base processing. Anyway, the general idea is there. Nicolas. net/core/dev.c | 70 +++++++++++++++++++++++++++++++++++++++++++++++= +-------- 1 files changed, 60 insertions(+), 10 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index e5dba47..7e007a9 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -3117,7 +3117,6 @@ static int __netif_receive_skb(struct sk_buff *sk= b) rx_handler_func_t *rx_handler; struct net_device *dev; struct net_device *orig_dev; - struct net_device *null_or_dev; int ret =3D NET_RX_DROP; __be16 type; @@ -3130,9 +3129,6 @@ static int __netif_receive_skb(struct sk_buff *sk= b) if (netpoll_receive_skb(skb)) return NET_RX_DROP; - skb->skb_iif =3D skb->dev->ifindex; - orig_dev =3D skb->dev; - skb_reset_network_header(skb); skb_reset_transport_header(skb); skb->mac_len =3D skb->network_header - skb->mac_header; @@ -3143,6 +3139,8 @@ static int __netif_receive_skb(struct sk_buff *sk= b) another_round: __this_cpu_inc(softnet_data.processed); + skb->skb_iif =3D skb->dev->ifindex; + orig_dev =3D skb->dev; dev =3D skb->dev; #ifdef CONFIG_NET_CLS_ACT @@ -3152,8 +3150,13 @@ another_round: } #endif + /* + * Deliver to ptype_all protocol handlers that match current dev. + * This happens before rx_handler is given a chance to change skb->de= v. + */ + list_for_each_entry_rcu(ptype, &ptype_all, list) { - if (!ptype->dev || ptype->dev =3D=3D dev) { + if (ptype->dev =3D=3D dev) { if (pt_prev) ret =3D deliver_skb(skb, pt_prev, orig_dev); pt_prev =3D ptype; @@ -3167,6 +3170,31 @@ another_round: ncls: #endif + /* + * Deliver to ptype_base protocol handlers that match current dev. + * This happens before rx_handler is given a chance to change skb->de= v. + */ + + type =3D skb->protocol; + list_for_each_entry_rcu(ptype, + &ptype_base[ntohs(type) & PTYPE_HASH_MASK], list) { + if (ptype->type =3D=3D type && ptype->dev =3D=3D skb->dev) { + if (pt_prev) + ret =3D deliver_skb(skb, pt_prev, orig_dev); + pt_prev =3D ptype; + } + } + + /* + * Call rx_handler for current device. + * If rx_handler return NULL, skip wilcard protocol handler delivery. + * Else, if skb->dev changed, restart the whole delivery process, to + * allow for device nesting. + * + * Warning: + * rx_handlers must kfree_skb(skb) if they return NULL. + */ + rx_handler =3D rcu_dereference(dev->rx_handler); if (rx_handler) { if (pt_prev) { @@ -3176,10 +3204,15 @@ ncls: skb =3D rx_handler(skb); if (!skb) goto out; - if (dev !=3D skb->dev) + if (skb->dev !=3D dev) goto another_round; } + /* + * FIXME: The part below should use rx_handler instead of being hard + * coded here. + */ + if (vlan_tx_tag_present(skb)) { if (pt_prev) { ret =3D deliver_skb(skb, pt_prev, orig_dev); @@ -3192,16 +3225,33 @@ ncls: goto out; } + /* + * FIXME: Can't this be moved into the rx_handler for bonding, + * or into a futur rx_handler for vlan? + */ + vlan_on_bond_hook(skb); - /* deliver only exact match when indicated */ - null_or_dev =3D skb->deliver_no_wcard ? skb->dev : NULL; + /* + * Deliver to wildcard ptype_all protocol handlers. + */ + + list_for_each_entry_rcu(ptype, &ptype_all, list) { + if (!ptype->dev) { + if (pt_prev) + ret =3D deliver_skb(skb, pt_prev, orig_dev); + pt_prev =3D ptype; + } + } + + /* + * Deliver to wildcard ptype_all protocol handlers. + */ type =3D skb->protocol; list_for_each_entry_rcu(ptype, &ptype_base[ntohs(type) & PTYPE_HASH_MASK], list) { - if (ptype->type =3D=3D type && - (ptype->dev =3D=3D null_or_dev || ptype->dev =3D=3D skb->dev)) { + if (ptype->type =3D=3D type && !ptype->dev) { if (pt_prev) ret =3D deliver_skb(skb, pt_prev, orig_dev); pt_prev =3D ptype; --=20 1.7.2.3