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Commit 5c25f686 authored by David S. Miller's avatar David S. Miller
Browse files

net: Kill support for multiple hh_cache entries per neighbour 



This never, ever, happens.

Neighbour entries are always tied to one address family, and therefore
one set of dst_ops, and therefore one dst_ops->protocol "hh_type"
value.

This capability was blindly imported by Alexey Kuznetsov when he wrote
the neighbour layer.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e69dd336

include/linux/netdevice.h

+2 −7
Original line number Diff line number Diff line
@@ -252,7 +252,6 @@ struct netdev_hw_addr_list { 
	netdev_hw_addr_list_for_each(ha, &(dev)->mc)



struct hh_cache {

	struct hh_cache *hh_next;	/* Next entry			     */

	atomic_t	hh_refcnt;	/* number of users                   */

/*

 * We want hh_output, hh_len, hh_lock and hh_data be a in a separate
@@ -260,12 +259,8 @@ struct hh_cache { 
 * They are mostly read, but hh_refcnt may be changed quite frequently,

 * incurring cache line ping pongs.

 */

	__be16		hh_type ____cacheline_aligned_in_smp;

					/* protocol identifier, f.e ETH_P_IP

                                         *  NOTE:  For VLANs, this will be the

                                         *  encapuslated type. --BLG

                                         */

	u16		hh_len;		/* length of header */

	u16		hh_len ____cacheline_aligned_in_smp;

	u16		__pad;

	int		(*hh_output)(struct sk_buff *skb);

	seqlock_t	hh_lock;

net/core/neighbour.c

+18 −19
Original line number Diff line number Diff line
@@ -702,9 +702,9 @@ void neigh_destroy(struct neighbour *neigh) 
	if (neigh_del_timer(neigh))

		printk(KERN_WARNING "Impossible event.\n");



	while ((hh = neigh->hh) != NULL) {

		neigh->hh = hh->hh_next;

		hh->hh_next = NULL;

	hh = neigh->hh;

	if (hh) {

		neigh->hh = NULL;



		write_seqlock_bh(&hh->hh_lock);

		hh->hh_output = neigh_blackhole;
@@ -737,7 +737,8 @@ static void neigh_suspect(struct neighbour *neigh) 


	neigh->output = neigh->ops->output;



	for (hh = neigh->hh; hh; hh = hh->hh_next)

	hh = neigh->hh;

	if (hh)

		hh->hh_output = neigh->ops->output;

}
@@ -754,7 +755,8 @@ static void neigh_connect(struct neighbour *neigh) 


	neigh->output = neigh->ops->connected_output;



	for (hh = neigh->hh; hh; hh = hh->hh_next)

	hh = neigh->hh;

	if (hh)

		hh->hh_output = neigh->ops->hh_output;

}
@@ -1025,7 +1027,8 @@ static void neigh_update_hhs(const struct neighbour *neigh) 
		update = neigh->dev->header_ops->cache_update;



	if (update) {

		for (hh = neigh->hh; hh; hh = hh->hh_next) {

		hh = neigh->hh;

		if (hh) {

			write_seqlock_bh(&hh->hh_lock);

			update(hh, neigh->dev, neigh->ha);

			write_sequnlock_bh(&hh->hh_lock);
@@ -1211,20 +1214,18 @@ 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)

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() */

	for (hh = n->hh; hh; hh = hh->hh_next) {

		if (hh->hh_type == protocol) {

	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;

}
@@ -1235,7 +1236,7 @@ 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, protocol)))

	if (likely(neigh_hh_lookup(n, dst)))

		return;



	/* slow path */
@@ -1244,7 +1245,6 @@ static void neigh_hh_init(struct neighbour *n, struct dst_entry *dst, 
		return;



	seqlock_init(&hh->hh_lock);

	hh->hh_type = protocol;

	atomic_set(&hh->hh_refcnt, 2);



	if (dev->header_ops->cache(n, hh, protocol)) {
@@ -1255,7 +1255,7 @@ static void neigh_hh_init(struct neighbour *n, struct dst_entry *dst, 
	write_lock_bh(&n->lock);



	/* must check if another thread already did the insert */

	if (neigh_hh_lookup(n, dst, protocol)) {

	if (neigh_hh_lookup(n, dst)) {

		kfree(hh);

		goto end;

	}
@@ -1265,7 +1265,6 @@ static void neigh_hh_init(struct neighbour *n, struct dst_entry *dst, 
	else

		hh->hh_output = n->ops->output;



	hh->hh_next = n->hh;

	smp_wmb(); /* paired with smp_rmb() in neigh_hh_lookup() */

	n->hh	    = hh;