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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2010-10-07 10:44:07 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2010-10-11 12:54:04 -0700 |
| commit | 0ed8ddf4045fcfcac36bad753dc4046118c603ec (patch) | |
| tree | cf1d9eb14668c4d2257b3519ed7deec8c5cb396d /include/net | |
| parent | d122179a3c0fdc71b88cb9e3605f372b1651a9ff (diff) | |
| download | linux-0ed8ddf4045fcfcac36bad753dc4046118c603ec.tar.gz linux-0ed8ddf4045fcfcac36bad753dc4046118c603ec.tar.bz2 linux-0ed8ddf4045fcfcac36bad753dc4046118c603ec.zip | |
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 <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net')
| -rw-r--r-- | include/net/neighbour.h | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/include/net/neighbour.h b/include/net/neighbour.h index a4538d553704..f04e7a2522c5 100644 --- a/include/net/neighbour.h +++ b/include/net/neighbour.h @@ -105,6 +105,7 @@ struct neighbour { atomic_t refcnt; atomic_t probes; rwlock_t lock; + seqlock_t ha_lock; unsigned char ha[ALIGN(MAX_ADDR_LEN, sizeof(unsigned long))]; struct hh_cache *hh; int (*output)(struct sk_buff *skb); @@ -302,7 +303,10 @@ static inline void neigh_confirm(struct neighbour *neigh) static inline int neigh_event_send(struct neighbour *neigh, struct sk_buff *skb) { - neigh->used = jiffies; + unsigned long now = ACCESS_ONCE(jiffies); + + if (neigh->used != now) + neigh->used = now; if (!(neigh->nud_state&(NUD_CONNECTED|NUD_DELAY|NUD_PROBE))) return __neigh_event_send(neigh, skb); return 0; @@ -373,4 +377,14 @@ struct neighbour_cb { #define NEIGH_CB(skb) ((struct neighbour_cb *)(skb)->cb) +static inline void neigh_ha_snapshot(char *dst, const struct neighbour *n, + const struct net_device *dev) +{ + unsigned int seq; + + do { + seq = read_seqbegin(&n->ha_lock); + memcpy(dst, n->ha, dev->addr_len); + } while (read_seqretry(&n->ha_lock, seq)); +} #endif |