Commit 96c36023 authored May 03, 2005 by Herbert Xu Committed by David S. Miller May 03, 2005

[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>

parent 9dfa277f

net/netlink/af_netlink.c

+0 −3

Original line number	Diff line number	Diff line
		@@ -373,7 +373,6 @@ static int netlink_release(struct socket *sock)
		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 @@ static int netlink_dump(struct sock *sk)
		spin_unlock(&nlk->cb_lock);

		netlink_destroy_callback(cb);
		__sock_put(sk);
		return 0;
		}

		@@ -1138,7 +1136,6 @@ int netlink_dump_start(struct sock ssk, struct sk_buff skb,
		return -EBUSY;
		}
		nlk->cb = cb;
		sock_hold(sk);
		spin_unlock(&nlk->cb_lock);

		netlink_dump(sk);