From 0ed8ddf4045fcfcac36bad753dc4046118c603ec Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 7 Oct 2010 10:44:07 +0000 Subject: neigh: Protect neigh->ha[] with a seqlock Add a seqlock in struct neighbour to protect neigh->ha[], and avoid dirtying neighbour in stress situation (many different flows / dsts) Dirtying takes place because of read_lock(&n->lock) and n->used writes. Switching to a seqlock, and writing n->used only on jiffies changes permits less dirtying. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/arp.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'net/ipv4/arp.c') diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c index f35309578170..d8e540c5b071 100644 --- a/net/ipv4/arp.c +++ b/net/ipv4/arp.c @@ -502,10 +502,8 @@ int arp_find(unsigned char *haddr, struct sk_buff *skb) if (n) { n->used = jiffies; - if (n->nud_state&NUD_VALID || neigh_event_send(n, skb) == 0) { - read_lock_bh(&n->lock); - memcpy(haddr, n->ha, dev->addr_len); - read_unlock_bh(&n->lock); + if (n->nud_state & NUD_VALID || neigh_event_send(n, skb) == 0) { + neigh_ha_snapshot(haddr, n, dev); neigh_release(n); return 0; } -- cgit v1.2.3