On Wed, 19 Jul 2006 13:01:50 -0700 (PDT) David Miller <[EMAIL PROTECTED]> wrote:
> From: Stephen Hemminger <[EMAIL PROTECTED]> > Date: Wed, 19 Jul 2006 15:52:04 -0400 > > > As a related note, I am looking into fixing inet hash tables to use RCU. > > IBM had posted a patch a long time ago, which would be not > so hard to munge into the current tree. See if you can > spot it in the archives :) Srivatsa Vaddagiri from IBM did patch: http://lkml.org/lkml/2004/8/31/129 And Ben had a patch: http://lwn.net/Articles/174596/ Srivata's was more complete but pre-dates Acme's rearrangement. Also, there is some code for refcnt's in it that looks wrong. Or at minimum is masking underlying design flaws. /* Ungrab socket and destroy it, if it was the last reference. */ static inline void sock_put(struct sock *sk) { - if (atomic_dec_and_test(&sk->sk_refcnt)) - sk_free(sk); +sp_loop: + if (atomic_dec_and_test(&sk->sk_refcnt)) { + /* Restore ref count and schedule callback. + * If we don't restore ref count, then the callback can be + * scheduled by more than one CPU. + */ + atomic_inc(&sk->sk_refcnt); + + if (atomic_read(&sk->sk_refcnt) == 1) + call_rcu(&sk->sk_rcu, sk_free_rcu); + else + goto sp_loop; + } } Ben's still left reader writer locks, and needed IPV6 work. He said he plans to get back to it. -- Stephen Hemminger <[EMAIL PROTECTED]> "And in the Packet there writ down that doome" - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
