Messages in this thread | | | Date | Tue, 21 Sep 2010 12:39:46 +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 01:58:30PM +0200, Eric Dumazet wrote: > Le mardi 21 septembre 2010 ?? 10:48 +0000, Jarek Poplawski a écrit : > > > 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: > > Nice try, but this adds a bug unfortunately, or if you prefer makes the > "BUG_ON(frag->sk);" being not fully covered. > > If we hit slow path, and one or more frags had frag->sk set, we silently > unset it, instead of a nice BUG_ON().
Which exactly BUG_ON() on the slow path do you mean?
> > If you really want to have a slow_path_clean, you should use a different > frag2 iterator : > > slow_path_clean: > if (skb->sk) { > skb_walk_frags(skb, frag2) { > if (frag2 == frag) > break; > frag2->sk = NULL; > frag2->destructor = NULL; > skb->truesize += frag2->truesize; > } > } > > Face it, this is too complex for net-2.6, could we just fix the bug, and > 'optimize' later ?
I thought it's clear I didn't intend to change anything with this example, but in any case I admit it: I'm 100% OK with your patch.
Jarek P. -- 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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