Messages in this thread Patch in this message | | | Date | Fri, 4 Feb 2005 12:55:39 +1100 | Subject | Re: [PATCH] arp_queue: serializing unlink + kfree_skb | From | Herbert Xu <> |
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On Thu, Feb 03, 2005 at 05:23:57PM -0800, David S. Miller wrote: > > You're absolutely right. Ok, so we do need to change kfree_skb(). > I believe even with the memory barrier, the atomic_read() optimization > is still worth it. atomic ops on sparc64 take a minimum of 40 some odd > cycles on UltraSPARC-III and later, whereas the memory barrier will > take up a single cycle most of the time.
OK, here is the patch to do that. Let's get rid of kfree_skb_fast while we're at it since it's no longer used.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Thanks, -- Visit Openswan at http://www.openswan.org/ Email: Herbert Xu ~{PmV>HI~} <herbert@gondor.apana.org.au> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt ===== include/linux/skbuff.h 1.59 vs edited ===== --- 1.59/include/linux/skbuff.h 2005-01-11 07:23:55 +11:00 +++ edited/include/linux/skbuff.h 2005-02-04 12:46:15 +11:00 @@ -353,15 +353,11 @@ */ static inline void kfree_skb(struct sk_buff *skb) { - if (atomic_read(&skb->users) == 1 || atomic_dec_and_test(&skb->users)) - __kfree_skb(skb); -} - -/* Use this if you didn't touch the skb state [for fast switching] */ -static inline void kfree_skb_fast(struct sk_buff *skb) -{ - if (atomic_read(&skb->users) == 1 || atomic_dec_and_test(&skb->users)) - kfree_skbmem(skb); + if (likely(atomic_read(&skb->users) == 1)) + smp_rmb(); + else if (likely(!atomic_dec_and_test(&skb->users))) + return; + __kfree_skb(skb); } /** | |