[PATCH 4.0 029/105] netlink: Disable insertions/removals during rehash

[Greg Kroah-Hartman]

4.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>

[ Upstream commit: Not applicable ]

The current rhashtable rehash code is buggy and can't deal with
parallel insertions/removals without corrupting the hash table.

This patch disables it by partially reverting
c5adde9468b0714a051eac7f9666f23eb10b61f7 ("netlink: eliminate
nl_sk_hash_lock").

Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/netlink/af_netlink.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1052,7 +1052,7 @@ static int netlink_insert(struct sock *s
 	struct netlink_table *table = &nl_table[sk->sk_protocol];
 	int err;
 
-	lock_sock(sk);
+	mutex_lock(&table->hash.mutex);
 
 	err = -EBUSY;
 	if (nlk_sk(sk)->portid)
@@ -1074,7 +1074,7 @@ static int netlink_insert(struct sock *s
 	}
 
 err:
-	release_sock(sk);
+	mutex_unlock(&table->hash.mutex);
 	return err;
 }
 
@@ -1083,10 +1083,12 @@ static void netlink_remove(struct sock *
 	struct netlink_table *table;
 
 	table = &nl_table[sk->sk_protocol];
+	mutex_lock(&table->hash.mutex);
 	if (rhashtable_remove(&table->hash, &nlk_sk(sk)->node)) {
 		WARN_ON(atomic_read(&sk->sk_refcnt) == 1);
 		__sock_put(sk);
 	}
+	mutex_unlock(&table->hash.mutex);
 
 	netlink_table_grab();
 	if (nlk_sk(sk)->subscriptions) {


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