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Commit f6b72b62 authored by David S. Miller's avatar David S. Miller
Browse files

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: default avatarDavid S. Miller <davem@davemloft.net>
parent 390fd0b3

include/linux/netdevice.h

+1 −14
Original line number Diff line number Diff line
@@ -252,14 +252,7 @@ struct netdev_hw_addr_list { 
	netdev_hw_addr_list_for_each(ha, &(dev)->mc)



struct hh_cache {

	atomic_t	hh_refcnt;	/* number of users                   */

/*

 * We want hh_output, hh_len, hh_lock and hh_data be a in a separate

 * cache line on SMP.

 * They are mostly read, but hh_refcnt may be changed quite frequently,

 * incurring cache line ping pongs.

 */

	u16		hh_len ____cacheline_aligned_in_smp;

	u16		hh_len;

	u16		__pad;

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

	seqlock_t	hh_lock;
@@ -273,12 +266,6 @@ 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 +

include/net/dst.h

+9 −9
Original line number Diff line number Diff line
@@ -38,7 +38,6 @@ struct dst_entry { 
	unsigned long		expires;

	struct dst_entry	*path;

	struct neighbour	*neighbour;

	struct hh_cache		*hh;

#ifdef CONFIG_XFRM

	struct xfrm_state	*xfrm;

#else
@@ -47,6 +46,14 @@ struct dst_entry { 
	int			(*input)(struct sk_buff*);

	int			(*output)(struct sk_buff*);



	int			flags;

#define DST_HOST		0x0001

#define DST_NOXFRM		0x0002

#define DST_NOPOLICY		0x0004

#define DST_NOHASH		0x0008

#define DST_NOCACHE		0x0010

#define DST_NOCOUNT		0x0020



	short			error;

	short			obsolete;

	unsigned short		header_len;	/* more space at head required */
@@ -62,7 +69,7 @@ struct dst_entry { 
	 * (L1_CACHE_SIZE would be too much)

	 */

#ifdef CONFIG_64BIT

	long			__pad_to_align_refcnt[1];

	long			__pad_to_align_refcnt[2];

#endif

	/*

	 * __refcnt wants to be on a different cache line from
@@ -71,13 +78,6 @@ struct dst_entry { 
	atomic_t		__refcnt;	/* client references	*/

	int			__use;

	unsigned long		lastuse;

	int			flags;

#define DST_HOST		0x0001

#define DST_NOXFRM		0x0002

#define DST_NOPOLICY		0x0004

#define DST_NOHASH		0x0008

#define DST_NOCACHE		0x0010

#define DST_NOCOUNT		0x0020

	union {

		struct dst_entry	*next;

		struct rtable __rcu	*rt_next;

include/net/neighbour.h

+1 −1
Original line number Diff line number Diff line
@@ -108,7 +108,7 @@ struct neighbour { 
	__u8			dead;

	seqlock_t		ha_lock;

	unsigned char		ha[ALIGN(MAX_ADDR_LEN, sizeof(unsigned long))];

	struct hh_cache		*hh;

	struct hh_cache		hh;

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

	const struct neigh_ops	*ops;

	struct rcu_head		rcu;

net/bridge/br_netfilter.c

+4 −2
Original line number Diff line number Diff line
@@ -343,14 +343,16 @@ static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb) 
static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)

{

	struct nf_bridge_info *nf_bridge = skb->nf_bridge;

	struct neighbour *neigh;

	struct dst_entry *dst;



	skb->dev = bridge_parent(skb->dev);

	if (!skb->dev)

		goto free_skb;

	dst = skb_dst(skb);

	if (dst->hh) {

		neigh_hh_bridge(dst->hh, skb);

	neigh = dst->neighbour;

	if (neigh->hh.hh_len) {

		neigh_hh_bridge(&neigh->hh, skb);

		skb->dev = nf_bridge->physindev;

		return br_handle_frame_finish(skb);

	} else if (dst->neighbour) {

net/core/dst.c

+0 −7
Original line number Diff line number Diff line
@@ -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);