From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Kirsher Subject: [net-next-2.6 PATCH] net: consolidate netif_needs_gso() checks Date: Wed, 16 Jun 2010 17:18:12 -0700 Message-ID: <20100617001804.5155.30862.stgit@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, gospo@redhat.com, bphilips@novell.com, John Fastabend , Herbert Xu , Jeff Kirsher To: davem@davemloft.net Return-path: Received: from qmta15.westchester.pa.mail.comcast.net ([76.96.59.228]:45807 "EHLO qmta15.westchester.pa.mail.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759128Ab0FQASe (ORCPT ); Wed, 16 Jun 2010 20:18:34 -0400 Sender: netdev-owner@vger.kernel.org List-ID: From: John Fastabend netif_needs_gso() is checked twice in the TX path once, before submitting the skb to the qdisc and once after it is dequeued from the qdisc just before calling ndo_hard_start(). This opens a window for a user to change the gso/tso or tx checksum settings that can cause netif_needs_gso to be true in one check and false in the other. Specifically, changing TX checksum setting may cause the warning in skb_gso_segment() to be triggered if the checksum is calculated earlier. This consolidates the netif_needs_gso() calls so that the stack only checks if gso is needed in dev_hard_start_xmit(). Signed-off-by: John Fastabend Cc: Herbert Xu Signed-off-by: Jeff Kirsher --- net/core/dev.c | 68 ++++++++++++++++++++++++++------------------------------ 1 files changed, 32 insertions(+), 36 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index 5902426..7f390b5 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -1895,6 +1895,22 @@ static inline void skb_orphan_try(struct sk_buff *skb) skb_orphan(skb); } +/* + * Returns true if either: + * 1. skb has frag_list and the device doesn't support FRAGLIST, or + * 2. skb is fragmented and the device does not support SG, or if + * at least one of fragments is in highmem and device does not + * support DMA from it. + */ +static inline int skb_needs_linearize(struct sk_buff *skb, + struct net_device *dev) +{ + return skb_is_nonlinear(skb) && + ((skb_has_frags(skb) && !(dev->features & NETIF_F_FRAGLIST)) || + (skb_shinfo(skb)->nr_frags && (!(dev->features & NETIF_F_SG) || + illegal_highdma(dev, skb)))); +} + int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev, struct netdev_queue *txq) { @@ -1919,6 +1935,22 @@ int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev, goto out_kfree_skb; if (skb->next) goto gso; + } else { + if (skb_needs_linearize(skb, dev) && + __skb_linearize(skb)) + goto out_kfree_skb; + + /* If packet is not checksummed and device does not + * support checksumming for this protocol, complete + * checksumming here. + */ + if (skb->ip_summed == CHECKSUM_PARTIAL) { + skb_set_transport_header(skb, skb->csum_start - + skb_headroom(skb)); + if (!dev_can_checksum(dev, skb) && + skb_checksum_help(skb)) + goto out_kfree_skb; + } } rc = ops->ndo_start_xmit(skb, dev); @@ -2089,22 +2121,6 @@ static inline int __dev_xmit_skb(struct sk_buff *skb, struct Qdisc *q, return rc; } -/* - * Returns true if either: - * 1. skb has frag_list and the device doesn't support FRAGLIST, or - * 2. skb is fragmented and the device does not support SG, or if - * at least one of fragments is in highmem and device does not - * support DMA from it. - */ -static inline int skb_needs_linearize(struct sk_buff *skb, - struct net_device *dev) -{ - return skb_is_nonlinear(skb) && - ((skb_has_frags(skb) && !(dev->features & NETIF_F_FRAGLIST)) || - (skb_shinfo(skb)->nr_frags && (!(dev->features & NETIF_F_SG) || - illegal_highdma(dev, skb)))); -} - /** * dev_queue_xmit - transmit a buffer * @skb: buffer to transmit @@ -2137,25 +2153,6 @@ int dev_queue_xmit(struct sk_buff *skb) struct Qdisc *q; int rc = -ENOMEM; - /* GSO will handle the following emulations directly. */ - if (netif_needs_gso(dev, skb)) - goto gso; - - /* Convert a paged skb to linear, if required */ - if (skb_needs_linearize(skb, dev) && __skb_linearize(skb)) - goto out_kfree_skb; - - /* If packet is not checksummed and device does not support - * checksumming for this protocol, complete checksumming here. - */ - if (skb->ip_summed == CHECKSUM_PARTIAL) { - skb_set_transport_header(skb, skb->csum_start - - skb_headroom(skb)); - if (!dev_can_checksum(dev, skb) && skb_checksum_help(skb)) - goto out_kfree_skb; - } - -gso: /* Disable soft irqs for various locks below. Also * stops preemption for RCU. */ @@ -2214,7 +2211,6 @@ gso: rc = -ENETDOWN; rcu_read_unlock_bh(); -out_kfree_skb: kfree_skb(skb); return rc; out: