[NETLINK]: cb_lock does not needs ref count on sk
Here is a little optimisation for the cb_lock used by netlink_dump.
While fixing that race earlier, I noticed that the reference count
held by cb_lock is completely useless. The reason is that in order
to obtain the protection of the reference count, you have to take
the cb_lock. But the only way to take the cb_lock is through
dereferencing the socket.
That is, you must already possess a reference count on the socket
before you can take advantage of the reference count held by cb_lock.
As a corollary, we can remve the reference count held by the cb_lock.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 29a5fd2..4ee39206 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -373,7 +373,6 @@
nlk->cb->done(nlk->cb);
netlink_destroy_callback(nlk->cb);
nlk->cb = NULL;
- __sock_put(sk);
}
spin_unlock(&nlk->cb_lock);
@@ -1099,7 +1098,6 @@
spin_unlock(&nlk->cb_lock);
netlink_destroy_callback(cb);
- __sock_put(sk);
return 0;
}
@@ -1138,7 +1136,6 @@
return -EBUSY;
}
nlk->cb = cb;
- sock_hold(sk);
spin_unlock(&nlk->cb_lock);
netlink_dump(sk);