From f6b72b6217f8c24f2a54988e58af858b4e66024d Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Thu, 14 Jul 2011 07:53:20 -0700 Subject: net: Embed hh_cache inside of struct neighbour. Now that there is a one-to-one correspondance between neighbour and hh_cache entries, we no longer need: 1) dynamic allocation 2) attachment to dst->hh 3) refcounting Initialization of the hh_cache entry is indicated by hh_len being non-zero, and such initialization is always done with the neighbour's lock held as a writer. Signed-off-by: David S. Miller --- net/core/dst.c | 7 ----- net/core/neighbour.c | 81 ++++++++++++++-------------------------------------- 2 files changed, 22 insertions(+), 66 deletions(-) (limited to 'net/core') diff --git a/net/core/dst.c b/net/core/dst.c index 6135f367169..4aacc14936a 100644 --- a/net/core/dst.c +++ b/net/core/dst.c @@ -172,7 +172,6 @@ void *dst_alloc(struct dst_ops *ops, struct net_device *dev, dst->expires = 0UL; dst->path = dst; dst->neighbour = NULL; - dst->hh = NULL; #ifdef CONFIG_XFRM dst->xfrm = NULL; #endif @@ -226,19 +225,13 @@ struct dst_entry *dst_destroy(struct dst_entry * dst) { struct dst_entry *child; struct neighbour *neigh; - struct hh_cache *hh; smp_rmb(); again: neigh = dst->neighbour; - hh = dst->hh; child = dst->child; - dst->hh = NULL; - if (hh) - hh_cache_put(hh); - if (neigh) { dst->neighbour = NULL; neigh_release(neigh); diff --git a/net/core/neighbour.c b/net/core/neighbour.c index f879bb55299..77a399f2ad0 100644 --- a/net/core/neighbour.c +++ b/net/core/neighbour.c @@ -297,6 +297,7 @@ static struct neighbour *neigh_alloc(struct neigh_table *tbl) n->updated = n->used = now; n->nud_state = NUD_NONE; n->output = neigh_blackhole; + seqlock_init(&n->hh.hh_lock); n->parms = neigh_parms_clone(&tbl->parms); setup_timer(&n->timer, neigh_timer_handler, (unsigned long)n); @@ -702,14 +703,11 @@ void neigh_destroy(struct neighbour *neigh) if (neigh_del_timer(neigh)) printk(KERN_WARNING "Impossible event.\n"); - hh = neigh->hh; - if (hh) { - neigh->hh = NULL; - + hh = &neigh->hh; + if (hh->hh_len) { write_seqlock_bh(&hh->hh_lock); hh->hh_output = neigh_blackhole; write_sequnlock_bh(&hh->hh_lock); - hh_cache_put(hh); } skb_queue_purge(&neigh->arp_queue); @@ -737,8 +735,8 @@ static void neigh_suspect(struct neighbour *neigh) neigh->output = neigh->ops->output; - hh = neigh->hh; - if (hh) + hh = &neigh->hh; + if (hh->hh_len) hh->hh_output = neigh->ops->output; } @@ -755,8 +753,8 @@ static void neigh_connect(struct neighbour *neigh) neigh->output = neigh->ops->connected_output; - hh = neigh->hh; - if (hh) + hh = &neigh->hh; + if (hh->hh_len) hh->hh_output = neigh->ops->hh_output; } @@ -1017,7 +1015,7 @@ out_unlock_bh: } EXPORT_SYMBOL(__neigh_event_send); -static void neigh_update_hhs(const struct neighbour *neigh) +static void neigh_update_hhs(struct neighbour *neigh) { struct hh_cache *hh; void (*update)(struct hh_cache*, const struct net_device*, const unsigned char *) @@ -1027,8 +1025,8 @@ static void neigh_update_hhs(const struct neighbour *neigh) update = neigh->dev->header_ops->cache_update; if (update) { - hh = neigh->hh; - if (hh) { + hh = &neigh->hh; + if (hh->hh_len) { write_seqlock_bh(&hh->hh_lock); update(hh, neigh->dev, neigh->ha); write_sequnlock_bh(&hh->hh_lock); @@ -1214,62 +1212,29 @@ struct neighbour *neigh_event_ns(struct neigh_table *tbl, } EXPORT_SYMBOL(neigh_event_ns); -static inline bool neigh_hh_lookup(struct neighbour *n, struct dst_entry *dst) -{ - struct hh_cache *hh; - - smp_rmb(); /* paired with smp_wmb() in neigh_hh_init() */ - hh = n->hh; - if (hh) { - atomic_inc(&hh->hh_refcnt); - if (unlikely(cmpxchg(&dst->hh, NULL, hh) != NULL)) - hh_cache_put(hh); - return true; - } - return false; -} - /* called with read_lock_bh(&n->lock); */ -static void neigh_hh_init(struct neighbour *n, struct dst_entry *dst, - __be16 protocol) +static void neigh_hh_init(struct neighbour *n, struct dst_entry *dst) { - struct hh_cache *hh; struct net_device *dev = dst->dev; - - if (likely(neigh_hh_lookup(n, dst))) - return; - - /* slow path */ - hh = kzalloc(sizeof(*hh), GFP_ATOMIC); - if (!hh) - return; - - seqlock_init(&hh->hh_lock); - atomic_set(&hh->hh_refcnt, 2); - - if (dev->header_ops->cache(n, hh, protocol)) { - kfree(hh); - return; - } + __be16 prot = dst->ops->protocol; + struct hh_cache *hh = &n->hh; write_lock_bh(&n->lock); - /* must check if another thread already did the insert */ - if (neigh_hh_lookup(n, dst)) { - kfree(hh); + /* Only one thread can come in here and initialize the + * hh_cache entry. + */ + if (hh->hh_len) + goto end; + + if (dev->header_ops->cache(n, hh, prot)) goto end; - } if (n->nud_state & NUD_CONNECTED) hh->hh_output = n->ops->hh_output; else hh->hh_output = n->ops->output; - smp_wmb(); /* paired with smp_rmb() in neigh_hh_lookup() */ - n->hh = hh; - - if (unlikely(cmpxchg(&dst->hh, NULL, hh) != NULL)) - hh_cache_put(hh); end: write_unlock_bh(&n->lock); } @@ -1312,10 +1277,8 @@ int neigh_resolve_output(struct sk_buff *skb) struct net_device *dev = neigh->dev; unsigned int seq; - if (dev->header_ops->cache && - !dst->hh && - !(dst->flags & DST_NOCACHE)) - neigh_hh_init(neigh, dst, dst->ops->protocol); + if (dev->header_ops->cache && !neigh->hh.hh_len) + neigh_hh_init(neigh, dst); do { seq = read_seqbegin(&neigh->ha_lock); -- cgit v1.2.3