[IPV6]: Acquire addrconf_hash_lock for read in addrconf_verify(...)

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 <yanzheng@21cn.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 56a09a4ac4105d69d548d0311dfbd50f7bbd8454..a16064ba0caf2bee3bcc87ffa111811d44927d60 100644 (file)
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -2627,7 +2627,7 @@ static void addrconf_verify(unsigned long foo)
        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;