netdev - Re: [PATCH net] ppp: don't override sk->sk_state in pppoe_flush

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Message-ID: <1445472897.4157.38.camel@mattb-dl>
Date:	Thu, 22 Oct 2015 00:14:57 +0000
From:	Matt Bennett <Matt.Bennett@...iedtelesis.co.nz>
To:	"nuclearcat@...learcat.com" <nuclearcat@...learcat.com>
CC:	"core@....lg.ua" <core@....lg.ua>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"davem@...emloft.net" <davem@...emloft.net>,
	"paulus@...ba.org" <paulus@...ba.org>,
	"g.nault@...halink.fr" <g.nault@...halink.fr>
Subject: Re: [PATCH net] ppp: don't override sk->sk_state in
 pppoe_flush_dev()

On Tue, 2015-10-13 at 05:13 +0300, Denys Fedoryshchenko wrote:
> On 2015-10-07 15:12, Guillaume Nault wrote:
> > On Mon, Oct 05, 2015 at 02:08:44PM +0200, Guillaume Nault wrote:
> >>  	if (po) {
> >>  		struct sock *sk = sk_pppox(po);
> >> 
> >> -		bh_lock_sock(sk);
> >> -
> >> -		/* If the user has locked the socket, just ignore
> >> -		 * the packet.  With the way two rcv protocols hook into
> >> -		 * one socket family type, we cannot (easily) distinguish
> >> -		 * what kind of SKB it is during backlog rcv.
> >> -		 */
> >> -		if (sock_owned_by_user(sk) == 0) {
> >> -			/* We're no longer connect at the PPPOE layer,
> >> -			 * and must wait for ppp channel to disconnect us.
> >> -			 */
> >> -			sk->sk_state = PPPOX_ZOMBIE;
> >> -		}
> >> -
> >> -		bh_unlock_sock(sk);
> >>  		if (!schedule_work(&po->proto.pppoe.padt_work))
> >>  			sock_put(sk);
> >>  	}
> >> 
> > Finally, I think I'll keep this approach for net-next, to completely
> > remove PPPOX_ZOMBIE.
> > For now, let's just avoid any assumption about the relationship between
> > the PPPOX_ZOMBIE state and the value of po->pppoe_dev, as suggested by
> > Matt.
> > 
> > Denys, can you let me know if your issue goes away with the following
> > patch?
> > ---
> > diff --git a/drivers/net/ppp/pppoe.c b/drivers/net/ppp/pppoe.c
> > index 2ed7506..5e0b432 100644
> > --- a/drivers/net/ppp/pppoe.c
> > +++ b/drivers/net/ppp/pppoe.c
> > @@ -589,7 +589,7 @@ static int pppoe_release(struct socket *sock)
> > 
> >  	po = pppox_sk(sk);
> > 
> > -	if (sk->sk_state & (PPPOX_CONNECTED | PPPOX_BOUND | PPPOX_ZOMBIE)) {
> > +	if (po->pppoe_dev) {
> >  		dev_put(po->pppoe_dev);
> >  		po->pppoe_dev = NULL;
> >  	}
> I just got OK to upgrade server yesterday, for now around 12 hours 
> working fine. I need 1-2 more days, and maybe will upgrade few more 
> servers to say for sure, if it is ok or not.
> Sorry for delay, just it is production servers and at current situation 
> they cannot tolerate significant downtime.
> 
Any update on whether this issue is fixed with the suggested patch?
> --
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