Re: [PATCH 1/1] Use RCU for the UDP hash lock

Jarek Poplawski
2008-09-26T05:46:22Z

On Thu, Sep 25, 2008 at 10:18:33PM -0500, Corey Minyard wrote:
...
> This patch is the second try; I believe I fixed all issues that people
> raised.

Actually, you've skipped my first question, so I still don't know, why
you don't use an _init version of sk_del_node (even if it's safe in the
current implementation), while the non-rcu code uses only this?

...
> diff --git a/include/net/sock.h b/include/net/sock.h
> index 06c5259..65110a6 100644
> --- a/include/net/sock.h
> +++ b/include/net/sock.h
...
> static inline int sk_unhashed(const struct sock *sk)
> {
> return hlist_unhashed(&sk->sk_node);
> @@ -361,6 +374,27 @@ static __inline__ int sk_del_node_init(struct sock *sk)
> return rc;
> }
>
> +static inline int __sk_del_node_rcu(struct sock *sk)
> +{
> + if (sk_hashed(sk)) {
> + hlist_del_rcu(&sk->sk_node);
> + return 1;
> + }
> + return 0;
> +}
> +
> +static inline int sk_del_node_rcu(struct sock *sk)
> +{
> + int rc = __sk_del_node_rcu(sk);
> +
> + if (rc) {
> + /* paranoid for a while -acme */
> + WARN_ON(atomic_read(&sk->sk_refcnt) == 1);
> + __sock_put(sk);
> + }
> + return rc;
> +}
...

Jarek P.