diff options
| author | Pravin B Shelar <pshelar@nicira.com> | 2013-06-17 17:49:32 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2013-06-19 18:07:40 -0700 |
| commit | 20fd4d1f04da07d09192ad8ad366a70d5125bfaf (patch) | |
| tree | a241ed7f086c88361c4b411bee7fb45839fffc69 /net/ipv4 | |
| parent | ac8025a643a0e0beb81f3f37ca693364c6b77858 (diff) | |
gre: Simplify gre protocol registration locking.
Use cmpxchg() for atomic protocol registration which saves
code and data space.
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/gre.c | 40 |
1 files changed, 13 insertions, 27 deletions
diff --git a/net/ipv4/gre.c b/net/ipv4/gre.c index b2e805af9b87..1e294d510ac3 100644 --- a/net/ipv4/gre.c +++ b/net/ipv4/gre.c @@ -26,46 +26,32 @@ static const struct gre_protocol __rcu *gre_proto[GREPROTO_MAX] __read_mostly; -static DEFINE_SPINLOCK(gre_proto_lock); int gre_add_protocol(const struct gre_protocol *proto, u8 version) { if (version >= GREPROTO_MAX) - goto err_out; - - spin_lock(&gre_proto_lock); - if (gre_proto[version]) - goto err_out_unlock; - - RCU_INIT_POINTER(gre_proto[version], proto); - spin_unlock(&gre_proto_lock); - return 0; + return -EINVAL; -err_out_unlock: - spin_unlock(&gre_proto_lock); -err_out: - return -1; + return (cmpxchg((const struct gre_protocol **)&gre_proto[version], NULL, proto) == NULL) ? + 0 : -EBUSY; } EXPORT_SYMBOL_GPL(gre_add_protocol); int gre_del_protocol(const struct gre_protocol *proto, u8 version) { + int ret; + if (version >= GREPROTO_MAX) - goto err_out; - - spin_lock(&gre_proto_lock); - if (rcu_dereference_protected(gre_proto[version], - lockdep_is_held(&gre_proto_lock)) != proto) - goto err_out_unlock; - RCU_INIT_POINTER(gre_proto[version], NULL); - spin_unlock(&gre_proto_lock); + return -EINVAL; + + ret = (cmpxchg((const struct gre_protocol **)&gre_proto[version], proto, NULL) == proto) ? + 0 : -EBUSY; + + if (ret) + return ret; + synchronize_rcu(); return 0; - -err_out_unlock: - spin_unlock(&gre_proto_lock); -err_out: - return -1; } EXPORT_SYMBOL_GPL(gre_del_protocol); |