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-rw-r--r--include/linux/netdevice.h6
-rw-r--r--net/core/dst.c4
-rw-r--r--net/core/neighbour.c99
3 files changed, 69 insertions, 40 deletions
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 6abcef67b178..4160db3721ba 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -281,6 +281,12 @@ struct hh_cache {
unsigned long hh_data[HH_DATA_ALIGN(LL_MAX_HEADER) / sizeof(long)];
};
+static inline void hh_cache_put(struct hh_cache *hh)
+{
+ if (atomic_dec_and_test(&hh->hh_refcnt))
+ kfree(hh);
+}
+
/* Reserve HH_DATA_MOD byte aligned hard_header_len, but at least that much.
* Alternative is:
* dev->hard_header_len ? (dev->hard_header_len +
diff --git a/net/core/dst.c b/net/core/dst.c
index 6c41b1fac3db..978a1ee1f7d0 100644
--- a/net/core/dst.c
+++ b/net/core/dst.c
@@ -228,8 +228,8 @@ again:
child = dst->child;
dst->hh = NULL;
- if (hh && atomic_dec_and_test(&hh->hh_refcnt))
- kfree(hh);
+ if (hh)
+ hh_cache_put(hh);
if (neigh) {
dst->neighbour = NULL;
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 3ffafaa0414c..2044906ecd1a 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -709,8 +709,7 @@ void neigh_destroy(struct neighbour *neigh)
write_seqlock_bh(&hh->hh_lock);
hh->hh_output = neigh_blackhole;
write_sequnlock_bh(&hh->hh_lock);
- if (atomic_dec_and_test(&hh->hh_refcnt))
- kfree(hh);
+ hh_cache_put(hh);
}
skb_queue_purge(&neigh->arp_queue);
@@ -1210,39 +1209,67 @@ 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,
+ __be16 protocol)
+{
+ struct hh_cache *hh;
+
+ for (hh = n->hh; hh; hh = hh->hh_next) {
+ if (hh->hh_type == protocol) {
+ 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)
{
struct hh_cache *hh;
struct net_device *dev = dst->dev;
- for (hh = n->hh; hh; hh = hh->hh_next)
- if (hh->hh_type == protocol)
- break;
+ if (likely(neigh_hh_lookup(n, dst, protocol)))
+ return;
- if (!hh && (hh = kzalloc(sizeof(*hh), GFP_ATOMIC)) != NULL) {
- seqlock_init(&hh->hh_lock);
- hh->hh_type = protocol;
- atomic_set(&hh->hh_refcnt, 0);
- hh->hh_next = NULL;
+ /* slow path */
+ hh = kzalloc(sizeof(*hh), GFP_ATOMIC);
+ if (!hh)
+ return;
- if (dev->header_ops->cache(n, hh)) {
- kfree(hh);
- hh = NULL;
- } else {
- atomic_inc(&hh->hh_refcnt);
- hh->hh_next = n->hh;
- n->hh = hh;
- if (n->nud_state & NUD_CONNECTED)
- hh->hh_output = n->ops->hh_output;
- else
- hh->hh_output = n->ops->output;
- }
+ seqlock_init(&hh->hh_lock);
+ hh->hh_type = protocol;
+ atomic_set(&hh->hh_refcnt, 2);
+
+ if (dev->header_ops->cache(n, hh)) {
+ kfree(hh);
+ return;
}
- if (hh) {
- atomic_inc(&hh->hh_refcnt);
- dst->hh = hh;
+ read_unlock(&n->lock);
+ write_lock(&n->lock);
+
+ /* must check if another thread already did the insert */
+ if (neigh_hh_lookup(n, dst, protocol)) {
+ kfree(hh);
+ goto end;
}
+
+ if (n->nud_state & NUD_CONNECTED)
+ hh->hh_output = n->ops->hh_output;
+ else
+ hh->hh_output = n->ops->output;
+
+ hh->hh_next = n->hh;
+ n->hh = hh;
+
+ if (unlikely(cmpxchg(&dst->hh, NULL, hh) != NULL))
+ hh_cache_put(hh);
+end:
+ write_unlock(&n->lock);
+ read_lock(&n->lock);
}
/* This function can be used in contexts, where only old dev_queue_xmit
@@ -1281,21 +1308,17 @@ int neigh_resolve_output(struct sk_buff *skb)
if (!neigh_event_send(neigh, skb)) {
int err;
struct net_device *dev = neigh->dev;
+
+ read_lock_bh(&neigh->lock);
if (dev->header_ops->cache &&
!dst->hh &&
- !(dst->flags & DST_NOCACHE)) {
- write_lock_bh(&neigh->lock);
- if (!dst->hh)
- neigh_hh_init(neigh, dst, dst->ops->protocol);
- err = dev_hard_header(skb, dev, ntohs(skb->protocol),
- neigh->ha, NULL, skb->len);
- write_unlock_bh(&neigh->lock);
- } else {
- read_lock_bh(&neigh->lock);
- err = dev_hard_header(skb, dev, ntohs(skb->protocol),
- neigh->ha, NULL, skb->len);
- read_unlock_bh(&neigh->lock);
- }
+ !(dst->flags & DST_NOCACHE))
+ neigh_hh_init(neigh, dst, dst->ops->protocol);
+
+ err = dev_hard_header(skb, dev, ntohs(skb->protocol),
+ neigh->ha, NULL, skb->len);
+ read_unlock_bh(&neigh->lock);
+
if (err >= 0)
rc = neigh->ops->queue_xmit(skb);
else