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

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Message-ID: <d5d182687f5319c9b4d82422b8c06789@visp.net.lb>
Date:	Thu, 22 Oct 2015 03:53:33 +0300
From:	Denys Fedoryshchenko <nuclearcat@...learcat.com>
To:	Matt Bennett <Matt.Bennett@...iedtelesis.co.nz>
Cc:	core@....lg.ua, netdev@...r.kernel.org, davem@...emloft.net,
	paulus@...ba.org, g.nault@...halink.fr
Subject: Re: [PATCH net] ppp: don't override sk->sk_state in pppoe_flush_dev()

On 2015-10-22 03:14, Matt Bennett wrote:
> 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?

As on server i am allowed to test - no crashed anymore, but i am unable 
to get permission yet to test
on server where this crash was happening several times per day. But all 
i can say it is definitely better now.

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