[PATCH v2] ipv6: replace write lock with read lock when get route info

[PATCH v2] ipv6: replace write lock with read lock when get route info

[roy.qing.li]

From: Li RongQing <roy.qing.li@gmail.com>

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>
---
 net/ipv6/addrconf.c |    4 ++--
 net/ipv6/route.c    |    8 ++++----
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 1237d5d..061c100 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -1706,7 +1706,7 @@ static struct rt6_info *addrconf_get_prefix_route(const struct in6_addr *pfx,
 	if (table == NULL)
 		return NULL;
 
-	write_lock_bh(&table->tb6_lock);
+	read_lock_bh(&table->tb6_lock);
 	fn = fib6_locate(&table->tb6_root, pfx, plen, NULL, 0);
 	if (!fn)
 		goto out;
@@ -1721,7 +1721,7 @@ static struct rt6_info *addrconf_get_prefix_route(const struct in6_addr *pfx,
 		break;
 	}
 out:
-	write_unlock_bh(&table->tb6_lock);
+	read_unlock_bh(&table->tb6_lock);
 	return rt;
 }
 
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 399613b..8be1d86 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1837,7 +1837,7 @@ static struct rt6_info *rt6_get_route_info(struct net *net,
 	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 @@ static struct rt6_info *rt6_get_route_info(struct net *net,
 		break;
 	}
 out:
-	write_unlock_bh(&table->tb6_lock);
+	read_unlock_bh(&table->tb6_lock);
 	return rt;
 }
 
@@ -1896,7 +1896,7 @@ struct rt6_info *rt6_get_dflt_router(const struct in6_addr *addr, struct net_dev
 	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 @@ struct rt6_info *rt6_get_dflt_router(const struct in6_addr *addr, struct net_dev
 	}
 	if (rt)
 		dst_hold(&rt->dst);
-	write_unlock_bh(&table->tb6_lock);
+	read_unlock_bh(&table->tb6_lock);
 	return rt;
 }
 
-- 
1.7.4.1

Re: [PATCH v2] ipv6: replace write lock with read lock when get route info

[Eric Dumazet]

On Wed, 2012-09-12 at 15:59 +0800, roy.qing.li@gmail.com wrote:
> From: Li RongQing <roy.qing.li@gmail.com>
> 
> 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>
> ---
>  net/ipv6/addrconf.c |    4 ++--
>  net/ipv6/route.c    |    8 ++++----
>  2 files changed, 6 insertions(+), 6 deletions(-)

I guess you missed the net-next tag in your [PATCH ...] ?
 
Signed-off-by: Eric Dumazet <edumazet@google.com>

Re: [PATCH v2] ipv6: replace write lock with read lock when get route info

[David Miller]

From: roy.qing.li@gmail.com
Date: Wed, 12 Sep 2012 15:59:01 +0800

> From: Li RongQing <roy.qing.li@gmail.com>
> 
> 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>

I'm surprised it's been like this for so long, but I can't find
any problems with your patch :-)

Applied to net-next, thanks.