From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: [PATCH] convert hh_lock to seqlock Date: Thu, 7 Dec 2006 11:33:09 -0800 Message-ID: <20061207113309.2f892cf1@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org Return-path: Received: from smtp.osdl.org ([65.172.181.25]:59248 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S938001AbWLGTdV (ORCPT ); Thu, 7 Dec 2006 14:33:21 -0500 To: David Miller Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org The hard header cache is in the main output path, so using seqlock instead of reader/writer lock should reduce overhead. Signed-off-by: Stephen Hemminger --- include/linux/netdevice.h | 2 +- include/net/neighbour.h | 18 ++++++++++++++++++ net/core/neighbour.c | 11 ++++++----- net/ipv4/ip_output.c | 14 +++----------- net/ipv6/ip6_output.c | 15 +++------------ 5 files changed, 31 insertions(+), 29 deletions(-) --- linux-2.6.19.orig/include/linux/netdevice.h 2006-12-05 13:55:54.000000000 -0800 +++ linux-2.6.19/include/linux/netdevice.h 2006-12-06 10:29:15.000000000 -0800 @@ -199,7 +199,7 @@ */ u16 hh_len; /* length of header */ int (*hh_output)(struct sk_buff *skb); - rwlock_t hh_lock; + seqlock_t hh_lock; /* cached hardware header; allow for machine alignment needs. */ #define HH_DATA_MOD 16 --- linux-2.6.19.orig/include/net/neighbour.h 2006-12-05 13:36:16.000000000 -0800 +++ linux-2.6.19/include/net/neighbour.h 2006-12-06 14:53:52.000000000 -0800 @@ -309,6 +309,24 @@ return 0; } +static inline int neigh_hh_output(struct hh_cache *hh, struct sk_buff *skb) +{ + unsigned seq; + int hh_len; + + do { + int hh_alen; + + seq = read_seqbegin(&hh->hh_lock); + hh_len = hh->hh_len; + hh_alen = HH_DATA_ALIGN(hh_len); + memcpy(skb->data - hh_alen, hh->hh_data, hh_alen); + } while (read_seqretry(&hh->hh_lock, seq)); + + skb_push(skb, hh_len); + return hh->hh_output(skb); +} + static inline struct neighbour * __neigh_lookup(struct neigh_table *tbl, const void *pkey, struct net_device *dev, int creat) { --- linux-2.6.19.orig/net/core/neighbour.c 2006-12-05 13:55:54.000000000 -0800 +++ linux-2.6.19/net/core/neighbour.c 2006-12-06 10:29:15.000000000 -0800 @@ -577,9 +577,10 @@ while ((hh = neigh->hh) != NULL) { neigh->hh = hh->hh_next; hh->hh_next = NULL; - write_lock_bh(&hh->hh_lock); + + write_seqlock_bh(&hh->hh_lock); hh->hh_output = neigh_blackhole; - write_unlock_bh(&hh->hh_lock); + write_sequnlock_bh(&hh->hh_lock); if (atomic_dec_and_test(&hh->hh_refcnt)) kfree(hh); } @@ -897,9 +898,9 @@ if (update) { for (hh = neigh->hh; hh; hh = hh->hh_next) { - write_lock_bh(&hh->hh_lock); + write_seqlock_bh(&hh->hh_lock); update(hh, neigh->dev, neigh->ha); - write_unlock_bh(&hh->hh_lock); + write_sequnlock_bh(&hh->hh_lock); } } } @@ -1089,7 +1090,7 @@ break; if (!hh && (hh = kzalloc(sizeof(*hh), GFP_ATOMIC)) != NULL) { - rwlock_init(&hh->hh_lock); + seqlock_init(&hh->hh_lock); hh->hh_type = protocol; atomic_set(&hh->hh_refcnt, 0); hh->hh_next = NULL; --- linux-2.6.19.orig/net/ipv4/ip_output.c 2006-12-05 13:55:54.000000000 -0800 +++ linux-2.6.19/net/ipv4/ip_output.c 2006-12-06 10:29:15.000000000 -0800 @@ -164,7 +164,6 @@ static inline int ip_finish_output2(struct sk_buff *skb) { struct dst_entry *dst = skb->dst; - struct hh_cache *hh = dst->hh; struct net_device *dev = dst->dev; int hh_len = LL_RESERVED_SPACE(dev); @@ -183,16 +182,9 @@ skb = skb2; } - if (hh) { - int hh_alen; - - read_lock_bh(&hh->hh_lock); - hh_alen = HH_DATA_ALIGN(hh->hh_len); - memcpy(skb->data - hh_alen, hh->hh_data, hh_alen); - read_unlock_bh(&hh->hh_lock); - skb_push(skb, hh->hh_len); - return hh->hh_output(skb); - } else if (dst->neighbour) + if (dst->hh) + return neigh_hh_output(dst->hh, skb); + else if (dst->neighbour) return dst->neighbour->output(skb); if (net_ratelimit()) --- linux-2.6.19.orig/net/ipv6/ip6_output.c 2006-12-05 13:55:54.000000000 -0800 +++ linux-2.6.19/net/ipv6/ip6_output.c 2006-12-06 10:33:24.000000000 -0800 @@ -72,20 +72,11 @@ static inline int ip6_output_finish(struct sk_buff *skb) { - struct dst_entry *dst = skb->dst; - struct hh_cache *hh = dst->hh; - - if (hh) { - int hh_alen; - read_lock_bh(&hh->hh_lock); - hh_alen = HH_DATA_ALIGN(hh->hh_len); - memcpy(skb->data - hh_alen, hh->hh_data, hh_alen); - read_unlock_bh(&hh->hh_lock); - skb_push(skb, hh->hh_len); - return hh->hh_output(skb); - } else if (dst->neighbour) + if (dst->hh) + return neigh_hh_output(dst->hh, skb); + else if (dst->neighbour) return dst->neighbour->output(skb); IP6_INC_STATS_BH(ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);