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authorLinus Torvalds <torvalds@linux-foundation.org>2011-05-27 11:16:27 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-05-27 11:16:27 -0700
commit10799db60cbc4f990dd69eb49883477095c66af7 (patch)
treeb87ac6acaa48f4f59f5d6a0b11490105876952e1 /net/ipv4
parentaaab184276a6e20834f63735d433f94ef52a0497 (diff)
parentc5c177b4aca83338781e72be2e6dd1601c560cb3 (diff)
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: net: Kill ratelimit.h dependency in linux/net.h net: Add linux/sysctl.h includes where needed. net: Kill ether_table[] declaration. inetpeer: fix race in unused_list manipulations atm: expose ATM device index in sysfs IPVS: bug in ip_vs_ftp, same list heaad used in all netns. bug.h: Move ratelimit warn interfaces to ratelimit.h bonding: cleanup module option descriptions net:8021q:vlan.c Fix pr_info to just give the vlan fullname and version. net: davinci_emac: fix dev_err use at probe can: convert to %pK for kptr_restrict support net: fix ETHTOOL_SFEATURES compatibility with old ethtool_ops.set_flags netfilter: Fix several warnings in compat_mtw_from_user(). netfilter: ipset: fix ip_set_flush return code netfilter: ipset: remove unused variable from type_pf_tdel() netfilter: ipset: Use proper timeout value to jiffies conversion
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/inetpeer.c42
1 files changed, 27 insertions, 15 deletions
diff --git a/net/ipv4/inetpeer.c b/net/ipv4/inetpeer.c
index 9df4e635fb5f..ce616d92cc54 100644
--- a/net/ipv4/inetpeer.c
+++ b/net/ipv4/inetpeer.c
@@ -154,11 +154,9 @@ void __init inet_initpeers(void)
/* Called with or without local BH being disabled. */
static void unlink_from_unused(struct inet_peer *p)
{
- if (!list_empty(&p->unused)) {
- spin_lock_bh(&unused_peers.lock);
- list_del_init(&p->unused);
- spin_unlock_bh(&unused_peers.lock);
- }
+ spin_lock_bh(&unused_peers.lock);
+ list_del_init(&p->unused);
+ spin_unlock_bh(&unused_peers.lock);
}
static int addr_compare(const struct inetpeer_addr *a,
@@ -205,6 +203,20 @@ static int addr_compare(const struct inetpeer_addr *a,
u; \
})
+static bool atomic_add_unless_return(atomic_t *ptr, int a, int u, int *newv)
+{
+ int cur, old = atomic_read(ptr);
+
+ while (old != u) {
+ *newv = old + a;
+ cur = atomic_cmpxchg(ptr, old, *newv);
+ if (cur == old)
+ return true;
+ old = cur;
+ }
+ return false;
+}
+
/*
* Called with rcu_read_lock()
* Because we hold no lock against a writer, its quite possible we fall
@@ -213,7 +225,8 @@ static int addr_compare(const struct inetpeer_addr *a,
* We exit from this function if number of links exceeds PEER_MAXDEPTH
*/
static struct inet_peer *lookup_rcu(const struct inetpeer_addr *daddr,
- struct inet_peer_base *base)
+ struct inet_peer_base *base,
+ int *newrefcnt)
{
struct inet_peer *u = rcu_dereference(base->root);
int count = 0;
@@ -226,7 +239,7 @@ static struct inet_peer *lookup_rcu(const struct inetpeer_addr *daddr,
* distinction between an unused entry (refcnt=0) and
* a freed one.
*/
- if (unlikely(!atomic_add_unless(&u->refcnt, 1, -1)))
+ if (!atomic_add_unless_return(&u->refcnt, 1, -1, newrefcnt))
u = NULL;
return u;
}
@@ -465,22 +478,23 @@ struct inet_peer *inet_getpeer(struct inetpeer_addr *daddr, int create)
struct inet_peer_base *base = family_to_base(daddr->family);
struct inet_peer *p;
unsigned int sequence;
- int invalidated;
+ int invalidated, newrefcnt = 0;
/* Look up for the address quickly, lockless.
* Because of a concurrent writer, we might not find an existing entry.
*/
rcu_read_lock();
sequence = read_seqbegin(&base->lock);
- p = lookup_rcu(daddr, base);
+ p = lookup_rcu(daddr, base, &newrefcnt);
invalidated = read_seqretry(&base->lock, sequence);
rcu_read_unlock();
if (p) {
- /* The existing node has been found.
+found: /* The existing node has been found.
* Remove the entry from unused list if it was there.
*/
- unlink_from_unused(p);
+ if (newrefcnt == 1)
+ unlink_from_unused(p);
return p;
}
@@ -494,11 +508,9 @@ struct inet_peer *inet_getpeer(struct inetpeer_addr *daddr, int create)
write_seqlock_bh(&base->lock);
p = lookup(daddr, stack, base);
if (p != peer_avl_empty) {
- atomic_inc(&p->refcnt);
+ newrefcnt = atomic_inc_return(&p->refcnt);
write_sequnlock_bh(&base->lock);
- /* Remove the entry from unused list if it was there. */
- unlink_from_unused(p);
- return p;
+ goto found;
}
p = create ? kmem_cache_alloc(peer_cachep, GFP_ATOMIC) : NULL;
if (p) {