2005-11-17 02:11:48

by Yan Zheng

Subject: [PATCH]IPv6: Acquire addrconf_hash_lock for reading instead of writing in addrconf_verify(...)

Hi.

addrconf_verify(...) only traverse address hash table when addrconf_hash_lock is held
for writing, and it may hold addrconf_hash_lock for a long time. So I think it's better
to acquire addrconf_hash_lock for reading instead of writing

Signed-off-by: Yan Zheng <[email protected]>

============================================================
--- a/net/ipv6/addrconf.c 2005-11-17 09:27:54.000000000 +0800
+++ b/net/ipv6/addrconf.c 2005-11-17 09:25:42.000000000 +0800
@@ -2627,7 +2627,7 @@ static void addrconf_verify(unsigned lon
for (i=0; i < IN6_ADDR_HSIZE; i++) {

restart:
- write_lock(&addrconf_hash_lock);
+ read_lock(&addrconf_hash_lock);
for (ifp=inet6_addr_lst[i]; ifp; ifp=ifp->lst_next) {
unsigned long age;
#ifdef CONFIG_IPV6_PRIVACY
@@ -2649,7 +2649,7 @@ restart:
if (age >= ifp->valid_lft) {
spin_unlock(&ifp->lock);
in6_ifa_hold(ifp);
- write_unlock(&addrconf_hash_lock);
+ read_unlock(&addrconf_hash_lock);
ipv6_del_addr(ifp);
goto restart;
} else if (age >= ifp->prefered_lft) {
@@ -2668,7 +2668,7 @@ restart:

if (deprecate) {
in6_ifa_hold(ifp);
- write_unlock(&addrconf_hash_lock);
+ read_unlock(&addrconf_hash_lock);

ipv6_ifa_notify(0, ifp);
in6_ifa_put(ifp);
@@ -2686,7 +2686,7 @@ restart:
in6_ifa_hold(ifp);
in6_ifa_hold(ifpub);
spin_unlock(&ifp->lock);
- write_unlock(&addrconf_hash_lock);
+ read_unlock(&addrconf_hash_lock);
ipv6_create_tempaddr(ifpub, ifp);
in6_ifa_put(ifpub);
in6_ifa_put(ifp);
@@ -2703,7 +2703,7 @@ restart:
spin_unlock(&ifp->lock);
}
}
- write_unlock(&addrconf_hash_lock);
+ read_unlock(&addrconf_hash_lock);
}

addr_chk_timer.expires = time_before(next, jiffies + HZ) ? jiffies + HZ : next;

2005-11-18 23:50:53

by David Miller

Subject: Re: [PATCH]IPv6: Acquire addrconf_hash_lock for reading instead of writing in addrconf_verify(...)

From: Yan Zheng <[email protected]>
Date: Thu, 17 Nov 2005 10:14:11 +0800

> addrconf_verify(...) only traverse address hash table when addrconf_hash_lock is held
> for writing, and it may hold addrconf_hash_lock for a long time. So I think it's better
> to acquire addrconf_hash_lock for reading instead of writing
>
> Signed-off-by: Yan Zheng <[email protected]>

Applied, thanks Yan.