From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm@xmission.com (Eric W. Biederman) Subject: [PATCH 06/10] netpoll: Don't drop all received packets. Date: Fri, 14 Mar 2014 20:48:28 -0700 Message-ID: <878uscp1f7.fsf_-_@xmission.com> References: <87eh28cvi6.fsf@xmission.com> <20140313.152311.1995854418463980325.davem@davemloft.net> <87eh24uu3d.fsf_-_@xmission.com> <20140314.225923.61318448733570839.davem@davemloft.net> <87k3bwqgf7.fsf@xmission.com> <877g7wqg8e.fsf_-_@xmission.com> Mime-Version: 1.0 Content-Type: text/plain Cc: stephen@networkplumber.org, eric.dumazet@gmail.com, netdev@vger.kernel.org, xiyou.wangcong@gmail.com, mpm@selenic.com, satyam.sharma@gmail.com To: David Miller Return-path: Received: from out03.mta.xmission.com ([166.70.13.233]:54616 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755570AbaCODse (ORCPT ); Fri, 14 Mar 2014 23:48:34 -0400 In-Reply-To: <877g7wqg8e.fsf_-_@xmission.com> (Eric W. Biederman's message of "Fri, 14 Mar 2014 20:43:13 -0700") Sender: netdev-owner@vger.kernel.org List-ID: Change the strategy of netpoll from dropping all packets received during netpoll_poll_dev to calling napi poll with a budget of 0 (to avoid processing drivers rx queue), and to ignore packets received with netif_rx (those will safely be placed on the backlog queue). All of the netpoll supporting drivers have been reviewed to ensure either thay use netif_rx or that a budget of 0 is supported by their napi poll routine and that a budget of 0 will not process the drivers rx queues. Not dropping packets makes NETPOLL_RX_DROP unnecesary so it is removed. npinfo->rx_flags is removed as rx_flags with just the NETPOLL_RX_ENABLED flag becomes just a redundant mirror of list_empty(&npinfo->rx_np). Signed-off-by: "Eric W. Biederman" --- include/linux/netpoll.h | 3 +-- net/core/netpoll.c | 17 ++++++----------- 2 files changed, 7 insertions(+), 13 deletions(-) diff --git a/include/linux/netpoll.h b/include/linux/netpoll.h index 479d15c97770..154f9776056c 100644 --- a/include/linux/netpoll.h +++ b/include/linux/netpoll.h @@ -39,7 +39,6 @@ struct netpoll { struct netpoll_info { atomic_t refcnt; - unsigned long rx_flags; spinlock_t rx_lock; struct semaphore dev_lock; struct list_head rx_np; /* netpolls that registered an rx_skb_hook */ @@ -99,7 +98,7 @@ static inline bool netpoll_rx_on(struct sk_buff *skb) { struct netpoll_info *npinfo = rcu_dereference_bh(skb->dev->npinfo); - return npinfo && (netpoll_rx_processing(npinfo) || npinfo->rx_flags); + return npinfo && netpoll_rx_processing(npinfo); } static inline bool netpoll_rx(struct sk_buff *skb) diff --git a/net/core/netpoll.c b/net/core/netpoll.c index ef83a2530e98..793dc04d2f19 100644 --- a/net/core/netpoll.c +++ b/net/core/netpoll.c @@ -51,8 +51,6 @@ static atomic_t trapped; DEFINE_STATIC_SRCU(netpoll_srcu); #define USEC_PER_POLL 50 -#define NETPOLL_RX_ENABLED 1 -#define NETPOLL_RX_DROP 2 #define MAX_SKB_SIZE \ (sizeof(struct ethhdr) + \ @@ -193,7 +191,8 @@ static void netpoll_poll_dev(struct net_device *dev) { const struct net_device_ops *ops; struct netpoll_info *ni = rcu_dereference_bh(dev->npinfo); - int budget = 16; + bool rx_processing = netpoll_rx_processing(ni); + int budget = rx_processing? 16 : 0; /* Don't do any rx activity if the dev_lock mutex is held * the dev_open/close paths use this to block netpoll activity @@ -207,8 +206,8 @@ static void netpoll_poll_dev(struct net_device *dev) return; } - ni->rx_flags |= NETPOLL_RX_DROP; - atomic_inc(&trapped); + if (rx_processing) + atomic_inc(&trapped); ops = dev->netdev_ops; if (!ops->ndo_poll_controller) { @@ -221,8 +220,8 @@ static void netpoll_poll_dev(struct net_device *dev) poll_napi(dev, budget); - atomic_dec(&trapped); - ni->rx_flags &= ~NETPOLL_RX_DROP; + if (rx_processing) + atomic_dec(&trapped); up(&ni->dev_lock); @@ -1050,7 +1049,6 @@ int __netpoll_setup(struct netpoll *np, struct net_device *ndev, gfp_t gfp) goto out; } - npinfo->rx_flags = 0; INIT_LIST_HEAD(&npinfo->rx_np); spin_lock_init(&npinfo->rx_lock); @@ -1076,7 +1074,6 @@ int __netpoll_setup(struct netpoll *np, struct net_device *ndev, gfp_t gfp) if (np->rx_skb_hook) { spin_lock_irqsave(&npinfo->rx_lock, flags); - npinfo->rx_flags |= NETPOLL_RX_ENABLED; list_add_tail(&np->rx, &npinfo->rx_np); spin_unlock_irqrestore(&npinfo->rx_lock, flags); } @@ -1258,8 +1255,6 @@ void __netpoll_cleanup(struct netpoll *np) if (!list_empty(&npinfo->rx_np)) { spin_lock_irqsave(&npinfo->rx_lock, flags); list_del(&np->rx); - if (list_empty(&npinfo->rx_np)) - npinfo->rx_flags &= ~NETPOLL_RX_ENABLED; spin_unlock_irqrestore(&npinfo->rx_lock, flags); } -- 1.7.5.4