Messages in this thread Patch in this message | | | Date | Tue, 21 Sep 2010 10:48:21 +0000 | From | Jarek Poplawski <> | Subject | Re: Regression, bisected: reference leak with IPSec since ~2.6.31 |
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On Tue, Sep 21, 2010 at 12:07:37PM +0200, Eric Dumazet wrote: > Le mardi 21 septembre 2010 ?? 11:55 +0200, Eric Dumazet a écrit : > > Le mardi 21 septembre 2010 ?? 09:38 +0000, Jarek Poplawski a écrit : > > > On Tue, Sep 21, 2010 at 11:21:00AM +0200, Eric Dumazet wrote: > > > > > I hope you're right with this. > > > > > > > > > > > I liked the : > > > > > > > > <check everything without changing state> > > > > if something wrong > > > > goto slow_path > > > > else > > > > <OK, lets do destructive things> > > > > > > > > > > But it's an optimization of the "unlikely" case btw. ;-) > > > > > > > This is a bug fix, in a complex function. > > > > in -next branch, we can try to be smart, adding more code in slow_path > > to revert what was done in the hope fast path would be taken. > > And pray we dont add another bug :)
But if you were honest about caches there is no reason to be smart no more. ;-)
Below is your patch mostly as an example only that I didn't mean nothing complex (ipv4 only, not compiled).
Jarek P. ---
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index 04b6989..049d61f 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -490,7 +490,6 @@ int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) if (skb_has_frags(skb)) { struct sk_buff *frag; int first_len = skb_pagelen(skb); - int truesizes = 0; if (first_len - hlen > mtu || ((first_len - hlen) & 7) || @@ -503,18 +502,18 @@ int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) if (frag->len > mtu || ((frag->len & 7) && frag->next) || skb_headroom(frag) < hlen) - goto slow_path; + goto slow_path_clean; /* Partially cloned skb? */ if (skb_shared(frag)) - goto slow_path; + goto slow_path_clean; BUG_ON(frag->sk); if (skb->sk) { frag->sk = skb->sk; frag->destructor = sock_wfree; + skb->truesize -= frag->truesize; } - truesizes += frag->truesize; } /* Everything is OK. Generate! */ @@ -524,7 +523,6 @@ int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) frag = skb_shinfo(skb)->frag_list; skb_frag_list_init(skb); skb->data_len = first_len - skb_headlen(skb); - skb->truesize -= truesizes; skb->len = first_len; iph->tot_len = htons(first_len); iph->frag_off = htons(IP_MF); @@ -576,6 +574,17 @@ int ip_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *)) } IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS); return err; + +slow_path_clean: + if (skb->sk) { + skb_walk_frags(skb, frag) { + if (!frag->sk) + break; + frag->sk = NULL; + frag->destructor = NULL; + skb->truesize += frag->truesize; + } + } } slow_path: -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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