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Date: Tue, 28 Aug 2012 07:12:34 -0700 From: Eric Dumazet <eric.dumazet@...il.com> To: Wei Yongjun <weiyj.lk@...il.com> Cc: davem@...emloft.net, yongjun_wei@...ndmicro.com.cn, netdev@...r.kernel.org Subject: Re: [PATCH] skbuff: remove pointless conditional before kfree_skb() On Tue, 2012-08-28 at 21:10 +0800, Wei Yongjun wrote: > From: Wei Yongjun <yongjun_wei@...ndmicro.com.cn> > > Remove pointless conditional before kfree_skb(). > > Signed-off-by: Wei Yongjun <yongjun_wei@...ndmicro.com.cn> > --- > include/linux/skbuff.h | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h > index 7632c87..0b846d9 100644 > --- a/include/linux/skbuff.h > +++ b/include/linux/skbuff.h > @@ -2464,8 +2464,7 @@ static inline void nf_conntrack_get_reasm(struct sk_buff *skb) > } > static inline void nf_conntrack_put_reasm(struct sk_buff *skb) > { > - if (skb) > - kfree_skb(skb); > + kfree_skb(skb); > } > #endif > #ifdef CONFIG_BRIDGE_NETFILTER > Its not exactly pointless. Its a tradeoff between kernel code size, and ability for cpu to predict a branch in kfree_skb() This test is in hot path, and therefore this patch can potentially have a performance impact. I really think most kfree_skb() calls are done with a non NULL param, so the branch prediction is good. But after this patch, things are totally different. Therefore, I am against it. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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