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ipv4: use seqlock for nh_exceptions

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Use global seqlock for the nh_exceptions. Call
fnhe_oldest with the right hash chain. Correct the diff
value for dst_set_expires.

v2: after suggestions from Eric Dumazet:
* get rid of spin lock fnhe_lock, rearrange update_or_create_fnhe
* continue daddr search in rt_bind_exception

v3:
* remove the daddr check before seqlock in rt_bind_exception
* restart lookup in rt_bind_exception on detected seqlock change,
as suggested by David Miller

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Julian Anastasov 2012-07-18 10:15:35 +00:00 committed by David S. Miller
parent 7fed84f622
commit aee06da672
2 changed files with 68 additions and 50 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/net/ip_fib.h
View File

@ -51,7 +51,7 @@ struct fib_nh_exception {
struct fib_nh_exception __rcu *fnhe_next;
__be32 fnhe_daddr;
u32 fnhe_pmtu;
u32 fnhe_gw;
__be32 fnhe_gw;
unsigned long fnhe_expires;
unsigned long fnhe_stamp;
};

116
net/ipv4/route.c
View File

@ -1333,9 +1333,9 @@ static void ip_rt_build_flow_key(struct flowi4 *fl4, const struct sock *sk,
build_sk_flow_key(fl4, sk);
}
static DEFINE_SPINLOCK(fnhe_lock);
static DEFINE_SEQLOCK(fnhe_seqlock);
static struct fib_nh_exception *fnhe_oldest(struct fnhe_hash_bucket *hash, __be32 daddr)
static struct fib_nh_exception *fnhe_oldest(struct fnhe_hash_bucket *hash)
{
struct fib_nh_exception *fnhe, *oldest;
@ -1358,47 +1358,63 @@ static inline u32 fnhe_hashfun(__be32 daddr)
return hval & (FNHE_HASH_SIZE - 1);
}
static struct fib_nh_exception *find_or_create_fnhe(struct fib_nh *nh, __be32 daddr)
static void update_or_create_fnhe(struct fib_nh *nh, __be32 daddr, __be32 gw,
u32 pmtu, unsigned long expires)
{
struct fnhe_hash_bucket *hash = nh->nh_exceptions;
struct fnhe_hash_bucket *hash;
struct fib_nh_exception *fnhe;
int depth;
u32 hval;
u32 hval = fnhe_hashfun(daddr);
write_seqlock_bh(&fnhe_seqlock);
hash = nh->nh_exceptions;
if (!hash) {
hash = nh->nh_exceptions = kzalloc(FNHE_HASH_SIZE * sizeof(*hash),
GFP_ATOMIC);
hash = kzalloc(FNHE_HASH_SIZE * sizeof(*hash), GFP_ATOMIC);
if (!hash)
return NULL;
goto out_unlock;
nh->nh_exceptions = hash;
}
hval = fnhe_hashfun(daddr);
hash += hval;
depth = 0;
for (fnhe = rcu_dereference(hash->chain); fnhe;
fnhe = rcu_dereference(fnhe->fnhe_next)) {
if (fnhe->fnhe_daddr == daddr)
goto out;
break;
depth++;
}
if (depth > FNHE_RECLAIM_DEPTH) {
fnhe = fnhe_oldest(hash + hval, daddr);
goto out_daddr;
if (fnhe) {
if (gw)
fnhe->fnhe_gw = gw;
if (pmtu) {
fnhe->fnhe_pmtu = pmtu;
fnhe->fnhe_expires = expires;
}
} else {
if (depth > FNHE_RECLAIM_DEPTH)
fnhe = fnhe_oldest(hash);
else {
fnhe = kzalloc(sizeof(*fnhe), GFP_ATOMIC);
if (!fnhe)
goto out_unlock;
fnhe->fnhe_next = hash->chain;
rcu_assign_pointer(hash->chain, fnhe);
}
fnhe->fnhe_daddr = daddr;
fnhe->fnhe_gw = gw;
fnhe->fnhe_pmtu = pmtu;
fnhe->fnhe_expires = expires;
}
fnhe = kzalloc(sizeof(*fnhe), GFP_ATOMIC);
if (!fnhe)
return NULL;
fnhe->fnhe_next = hash->chain;
rcu_assign_pointer(hash->chain, fnhe);
out_daddr:
fnhe->fnhe_daddr = daddr;
out:
fnhe->fnhe_stamp = jiffies;
return fnhe;
out_unlock:
write_sequnlock_bh(&fnhe_seqlock);
return;
}
static void __ip_do_redirect(struct rtable *rt, struct sk_buff *skb, struct flowi4 *fl4)
@ -1452,13 +1468,9 @@ static void __ip_do_redirect(struct rtable *rt, struct sk_buff *skb, struct flow
} else {
if (fib_lookup(net, fl4, &res) == 0) {
struct fib_nh *nh = &FIB_RES_NH(res);
struct fib_nh_exception *fnhe;
spin_lock_bh(&fnhe_lock);
fnhe = find_or_create_fnhe(nh, fl4->daddr);
if (fnhe)
fnhe->fnhe_gw = new_gw;
spin_unlock_bh(&fnhe_lock);
update_or_create_fnhe(nh, fl4->daddr, new_gw,
0, 0);
}
rt->rt_gateway = new_gw;
rt->rt_flags |= RTCF_REDIRECTED;
@ -1663,15 +1675,9 @@ static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
if (fib_lookup(dev_net(rt->dst.dev), fl4, &res) == 0) {
struct fib_nh *nh = &FIB_RES_NH(res);
struct fib_nh_exception *fnhe;
spin_lock_bh(&fnhe_lock);
fnhe = find_or_create_fnhe(nh, fl4->daddr);
if (fnhe) {
fnhe->fnhe_pmtu = mtu;
fnhe->fnhe_expires = jiffies + ip_rt_mtu_expires;
}
spin_unlock_bh(&fnhe_lock);
update_or_create_fnhe(nh, fl4->daddr, 0, mtu,
jiffies + ip_rt_mtu_expires);
}
rt->rt_pmtu = mtu;
dst_set_expires(&rt->dst, ip_rt_mtu_expires);
@ -1902,23 +1908,35 @@ static void rt_bind_exception(struct rtable *rt, struct fib_nh *nh, __be32 daddr
hval = fnhe_hashfun(daddr);
restart:
for (fnhe = rcu_dereference(hash[hval].chain); fnhe;
fnhe = rcu_dereference(fnhe->fnhe_next)) {
if (fnhe->fnhe_daddr == daddr) {
if (fnhe->fnhe_pmtu) {
unsigned long expires = fnhe->fnhe_expires;
unsigned long diff = expires - jiffies;
__be32 fnhe_daddr, gw;
unsigned long expires;
unsigned int seq;
u32 pmtu;
if (time_before(jiffies, expires)) {
rt->rt_pmtu = fnhe->fnhe_pmtu;
dst_set_expires(&rt->dst, diff);
}
seq = read_seqbegin(&fnhe_seqlock);
fnhe_daddr = fnhe->fnhe_daddr;
gw = fnhe->fnhe_gw;
pmtu = fnhe->fnhe_pmtu;
expires = fnhe->fnhe_expires;
if (read_seqretry(&fnhe_seqlock, seq))
goto restart;
if (daddr != fnhe_daddr)
continue;
if (pmtu) {
unsigned long diff = jiffies - expires;
if (time_before(jiffies, expires)) {
rt->rt_pmtu = pmtu;
dst_set_expires(&rt->dst, diff);
}
if (fnhe->fnhe_gw)
rt->rt_gateway = fnhe->fnhe_gw;
fnhe->fnhe_stamp = jiffies;
break;
}
if (gw)
rt->rt_gateway = gw;
fnhe->fnhe_stamp = jiffies;
break;
}
}