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

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Message-ID: <20151007121232.GF2882@alphalink.fr>
Date:	Wed, 7 Oct 2015 14:12:32 +0200
From:	Guillaume Nault <g.nault@...halink.fr>
To:	Denys Fedoryshchenko <nuclearcat@...learcat.com>
Cc:	netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
	Paul Mackerras <paulus@...ba.org>,
	Oleksii Berezhniak <core@....lg.ua>,
	Matt Bennett <Matt.Bennett@...iedtelesis.co.nz>
Subject: Re: [PATCH net] ppp: don't override sk->sk_state in pppoe_flush_dev()

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;
 	}
--
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