Messages in this thread Patch in this message | | | Date | Wed, 28 Nov 2012 00:51:29 +0100 | From | Krzysztof Mazur <> | Subject | Re: [PATCH] br2684: don't send frames on not-ready vcc |
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On Tue, Nov 27, 2012 at 11:28:36PM +0000, David Woodhouse wrote: > Avoid submitting patches to a vcc which is being closed. Things go badly > wrong when the ->pop method gets later called after everything's been > torn down. > > Signed-off-by: David Woodhouse <David.Woodhouse@intel.com> > --- > On Tue, 2012-11-27 at 22:36 +0000, David Woodhouse wrote: > > Nathan, does this help? > > I think that's necessary, but not sufficient. You'll want something like > this too... I can now kill br2684ctl while there's a flood of outgoing > packets, and get a handful of the printks that I had in here until a few > seconds ago when I edited it out of the patch in my mail client... and > no more panic. > > I do also now have Krzysztof's patch 1/7 (detach protocol before closing > vcc) but I don't think it actually matters any more.
If you do this actually it's better to don't use patch 1/7 because it introduces race condition that you found earlier.
> > --- a/net/atm/br2684.c~ 2012-11-23 23:14:29.000000000 +0000 > +++ b/net/atm/br2684.c 2012-11-27 23:09:18.502403881 +0000 > @@ -249,6 +249,12 @@ static int br2684_xmit_vcc(struct sk_buf > skb_debug(skb); > > ATM_SKB(skb)->vcc = atmvcc = brvcc->atmvcc; > + if (test_bit(ATM_VF_RELEASED, &atmvcc->flags) > + || test_bit(ATM_VF_CLOSE, &atmvcc->flags) > + || !test_bit(ATM_VF_READY, &atmvcc->flags)) { > + dev_kfree_skb(skb); > + return 0; > + } > pr_debug("atm_skb(%p)->vcc(%p)->dev(%p)\n", skb, atmvcc, atmvcc->dev); > atomic_add(skb->truesize, &sk_atm(atmvcc)->sk_wmem_alloc); > ATM_SKB(skb)->atm_options = atmvcc->atm_options; >
With this patch you have still theoretical race that was fixed in patches 5 and 8 in pppoatm series, but I never seen that in practice.
Acked-by: Krzysztof Mazur <krzysiek@podlesie.net>
Krzysiek
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