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[NET]: Convert hh_lock to seqlock.

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The hard header cache is in the main output path, so using
seqlock instead of reader/writer lock should reduce overhead.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Stephen Hemminger 2006-12-07 15:08:17 -08:00 committed by David S. Miller
parent eb991b3938
commit 3644f0cee7
5 changed files with 31 additions and 29 deletions
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2
include/linux/netdevice.h
View File

@ -199,7 +199,7 @@ struct hh_cache
*/
u16 hh_len; /* length of header */
int (*hh_output)(struct sk_buff *skb);
rwlock_t hh_lock;
seqlock_t hh_lock;
/* cached hardware header; allow for machine alignment needs. */
#define HH_DATA_MOD 16

18
include/net/neighbour.h
View File

@ -309,6 +309,24 @@ static inline int neigh_event_send(struct neighbour *neigh, struct sk_buff *skb)
return 0;
}
static inline int neigh_hh_output(struct hh_cache *hh, struct sk_buff *skb)
{
unsigned seq;
int hh_len;
do {
int hh_alen;
seq = read_seqbegin(&hh->hh_lock);
hh_len = hh->hh_len;
hh_alen = HH_DATA_ALIGN(hh_len);
memcpy(skb->data - hh_alen, hh->hh_data, hh_alen);
} while (read_seqretry(&hh->hh_lock, seq));
skb_push(skb, hh_len);
return hh->hh_output(skb);
}
static inline struct neighbour *
__neigh_lookup(struct neigh_table *tbl, const void *pkey, struct net_device *dev, int creat)
{

11
net/core/neighbour.c
View File

@ -577,9 +577,10 @@ void neigh_destroy(struct neighbour *neigh)
while ((hh = neigh->hh) != NULL) {
neigh->hh = hh->hh_next;
hh->hh_next = NULL;
write_lock_bh(&hh->hh_lock);
write_seqlock_bh(&hh->hh_lock);
hh->hh_output = neigh_blackhole;
write_unlock_bh(&hh->hh_lock);
write_sequnlock_bh(&hh->hh_lock);
if (atomic_dec_and_test(&hh->hh_refcnt))
kfree(hh);
}
@ -897,9 +898,9 @@ static void neigh_update_hhs(struct neighbour *neigh)
if (update) {
for (hh = neigh->hh; hh; hh = hh->hh_next) {
write_lock_bh(&hh->hh_lock);
write_seqlock_bh(&hh->hh_lock);
update(hh, neigh->dev, neigh->ha);
write_unlock_bh(&hh->hh_lock);
write_sequnlock_bh(&hh->hh_lock);
}
}
}
@ -1089,7 +1090,7 @@ static void neigh_hh_init(struct neighbour *n, struct dst_entry *dst,
break;
if (!hh && (hh = kzalloc(sizeof(*hh), GFP_ATOMIC)) != NULL) {
rwlock_init(&hh->hh_lock);
seqlock_init(&hh->hh_lock);
hh->hh_type = protocol;
atomic_set(&hh->hh_refcnt, 0);
hh->hh_next = NULL;

14
net/ipv4/ip_output.c
View File

@ -164,7 +164,6 @@ EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
static inline int ip_finish_output2(struct sk_buff *skb)
{
struct dst_entry *dst = skb->dst;
struct hh_cache *hh = dst->hh;
struct net_device *dev = dst->dev;
int hh_len = LL_RESERVED_SPACE(dev);
@ -183,16 +182,9 @@ static inline int ip_finish_output2(struct sk_buff *skb)
skb = skb2;
}
if (hh) {
int hh_alen;
read_lock_bh(&hh->hh_lock);
hh_alen = HH_DATA_ALIGN(hh->hh_len);
memcpy(skb->data - hh_alen, hh->hh_data, hh_alen);
read_unlock_bh(&hh->hh_lock);
skb_push(skb, hh->hh_len);
return hh->hh_output(skb);
} else if (dst->neighbour)
if (dst->hh)
return neigh_hh_output(dst->hh, skb);
else if (dst->neighbour)
return dst->neighbour->output(skb);
if (net_ratelimit())

15
net/ipv6/ip6_output.c
View File

@ -72,20 +72,11 @@ static __inline__ void ipv6_select_ident(struct sk_buff *skb, struct frag_hdr *f
static inline int ip6_output_finish(struct sk_buff *skb)
{
struct dst_entry *dst = skb->dst;
struct hh_cache *hh = dst->hh;
if (hh) {
int hh_alen;
read_lock_bh(&hh->hh_lock);
hh_alen = HH_DATA_ALIGN(hh->hh_len);
memcpy(skb->data - hh_alen, hh->hh_data, hh_alen);
read_unlock_bh(&hh->hh_lock);
skb_push(skb, hh->hh_len);
return hh->hh_output(skb);
} else if (dst->neighbour)
if (dst->hh)
return neigh_hh_output(dst->hh, skb);
else if (dst->neighbour)
return dst->neighbour->output(skb);
IP6_INC_STATS_BH(ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);