commit 5744dd9b71c6b9df944c6a32a000d4a564a2abd7
author Li RongQing <roy.qing.li@gmail.com> Tue Sep 11 21:59:01 2012 +0000
committer David S. Miller <davem@davemloft.net> Thu Sep 13 16:53:46 2012 -0400
tree 5d40eb61a4152f32fa15afdfded741648cfc28c7
parent fb0af4c74f200e3c4846d91d8f2f8b265450bba7

ipv6: replace write lock with read lock when get route info

geting route info does not write rt->rt6i_table, so replace
write lock with read lock

Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Li RongQing <roy.qing.li@gmail.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/route.c

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index f568ac6..83dafa5 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1837,7 +1837,7 @@
 	if (!table)
 		return NULL;
 
-	write_lock_bh(&table->tb6_lock);
+	read_lock_bh(&table->tb6_lock);
 	fn = fib6_locate(&table->tb6_root, prefix ,prefixlen, NULL, 0);
 	if (!fn)
 		goto out;
@@ -1853,7 +1853,7 @@
 		break;
 	}
 out:
-	write_unlock_bh(&table->tb6_lock);
+	read_unlock_bh(&table->tb6_lock);
 	return rt;
 }
 
@@ -1896,7 +1896,7 @@
 	if (!table)
 		return NULL;
 
-	write_lock_bh(&table->tb6_lock);
+	read_lock_bh(&table->tb6_lock);
 	for (rt = table->tb6_root.leaf; rt; rt=rt->dst.rt6_next) {
 		if (dev == rt->dst.dev &&
 		    ((rt->rt6i_flags & (RTF_ADDRCONF | RTF_DEFAULT)) == (RTF_ADDRCONF | RTF_DEFAULT)) &&
@@ -1905,7 +1905,7 @@
 	}
 	if (rt)
 		dst_hold(&rt->dst);
-	write_unlock_bh(&table->tb6_lock);
+	read_unlock_bh(&table->tb6_lock);
 	return rt;
 }