Subject: Re: kernel panic in latest vanilla stable, while using nameif with "alive" pppoe interfaces

From: Denys Fedoryschenko <[email-masked]>
Date: Tue, 20 Oct 2009 17:20:00 +0300

It panics almost immediately on boot(even on old operations  that was stable, 
seems on first pppoe customer login attempt), i will rebuild kernel and if 
interesting will try to get panic message.

On Tuesday 20 October 2009 16:59:20 Cyrill Gorcunov wrote:
> [Denys Fedoryschenko - Tue, Oct 20, 2009 at 04:50:09PM +0300]
>
> ...
>
> | > Thanks Denys, I'm preparing new patch (just back from office
> | > and had no inet connection that is why reply is delayed, sorry).
> |
> | There is no problem at all.
> | This rename operation is just future operation and host is redundant, so
> | i can do tests on it anytime.
>
> ok, here is it, please try (it's still a draft version though)
>
> 	-- Cyrill
> ---
>  drivers/net/pppoe.c |  106
> +++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 81
> insertions(+), 25 deletions(-)
>
> Index: linux-2.6.git/drivers/net/pppoe.c
> =====================================================================
> --- linux-2.6.git.orig/drivers/net/pppoe.c
> +++ linux-2.6.git/drivers/net/pppoe.c
> @@ -313,8 +313,8 @@ static void pppoe_flush_dev(struct net_d
>  			sk = sk_pppox(po);
>  			spin_lock(&flush_lock);
>  			po->pppoe_dev = NULL;
> -			spin_unlock(&flush_lock);
>  			dev_put(dev);
> +			spin_unlock(&flush_lock);
>
>  			/* We always grab the socket lock, followed by the
>  			 * hash_lock, in that order.  Since we should
> @@ -386,13 +386,21 @@ static struct notifier_block pppoe_notif
>  static int pppoe_rcv_core(struct sock *sk, struct sk_buff *skb)
>  {
>  	struct pppox_sock *po = pppox_sk(sk);
> -	struct pppox_sock *relay_po;
> +	struct pppox_sock *relay_po = NULL;
> +	struct net_device *dev = NULL;
>
>  	if (sk->sk_state & PPPOX_BOUND) {
>  		ppp_input(&po->chan, skb);
>  	} else if (sk->sk_state & PPPOX_RELAY) {
> -		relay_po = get_item_by_addr(dev_net(po->pppoe_dev),
> -						&po->pppoe_relay);
> +		struct pppoe_net *pn = pppoe_pernet(sock_net(sk));
> +		read_lock_bh(&pn->hash_lock);
> +		dev = po->pppoe_dev;
> +		if (dev) {
> +			dev_hold(dev);
> +			relay_po = get_item_by_addr(dev_net(dev),
> +					&po->pppoe_relay);
> +		}
> +		read_unlock_bh(&pn->hash_lock);
>  		if (relay_po == NULL)
>  			goto abort_kfree;
>
> @@ -401,6 +409,7 @@ static int pppoe_rcv_core(struct sock *s
>
>  		if (!__pppoe_xmit(sk_pppox(relay_po), skb))
>  			goto abort_put;
> +		dev_put(dev);
>  	} else {
>  		if (sock_queue_rcv_skb(sk, skb))
>  			goto abort_kfree;
> @@ -412,6 +421,8 @@ abort_put:
>  	sock_put(sk_pppox(relay_po));
>
>  abort_kfree:
> +	if (dev)
> +		dev_put(dev);
>  	kfree_skb(skb);
>  	return NET_RX_DROP;
>  }
> @@ -625,8 +636,8 @@ static int pppoe_connect(struct socket *
>  	struct sock *sk = sock->sk;
>  	struct sockaddr_pppox *sp = (struct sockaddr_pppox *)uservaddr;
>  	struct pppox_sock *po = pppox_sk(sk);
> -	struct net_device *dev;
> -	struct pppoe_net *pn;
> +	struct net_device *dev = NULL;
> +	struct pppoe_net *pn = NULL;
>  	int error;
>
>  	lock_sock(sk);
> @@ -652,12 +663,15 @@ static int pppoe_connect(struct socket *
>  	/* Delete the old binding */
>  	if (stage_session(po->pppoe_pa.sid)) {
>  		pppox_unbind_sock(sk);
> +		spin_lock(&flush_lock);
>  		if (po->pppoe_dev) {
>  			pn = pppoe_pernet(dev_net(po->pppoe_dev));
>  			delete_item(pn, po->pppoe_pa.sid,
>  				po->pppoe_pa.remote, po->pppoe_ifindex);
>  			dev_put(po->pppoe_dev);
> +			po->pppoe_dev = NULL;
>  		}
> +		spin_unlock(&flush_lock);
>  		memset(sk_pppox(po) + 1, 0,
>  		       sizeof(struct pppox_sock) - sizeof(struct sock));
>  		sk->sk_state = PPPOX_NONE;
> @@ -670,10 +684,11 @@ static int pppoe_connect(struct socket *
>  		if (!dev)
>  			goto end;
>
> +		write_lock_bh(&pn->hash_lock);
> +		dev_hold(dev);
>  		po->pppoe_dev = dev;
>  		po->pppoe_ifindex = dev->ifindex;
>  		pn = pppoe_pernet(dev_net(dev));
> -		write_lock_bh(&pn->hash_lock);
>  		if (!(dev->flags & IFF_UP)) {
>  			write_unlock_bh(&pn->hash_lock);
>  			goto err_put;
> @@ -700,6 +715,7 @@ static int pppoe_connect(struct socket *
>  			goto err_put;
>
>  		sk->sk_state = PPPOX_CONNECTED;
> +		dev_put(dev);
>  	}
>
>  	po->num = sp->sa_addr.pppoe.sid;
> @@ -708,10 +724,13 @@ end:
>  	release_sock(sk);
>  	return error;
>  err_put:
> +	dev_put(dev);
> +	write_lock_bh(&pn->hash_lock);
>  	if (po->pppoe_dev) {
>  		dev_put(po->pppoe_dev);
>  		po->pppoe_dev = NULL;
>  	}
> +	write_unlock_bh(&pn->hash_lock);
>  	goto end;
>  }
>
> @@ -738,6 +757,8 @@ static int pppoe_ioctl(struct socket *so
>  {
>  	struct sock *sk = sock->sk;
>  	struct pppox_sock *po = pppox_sk(sk);
> +	struct pppoe_net *pn = pppoe_pernet(sock_net(sk));
> +	unsigned int mtu = 0;
>  	int val;
>  	int err;
>
> @@ -746,11 +767,17 @@ static int pppoe_ioctl(struct socket *so
>  		err = -ENXIO;
>  		if (!(sk->sk_state & PPPOX_CONNECTED))
>  			break;
> -
> +		read_lock_bh(&pn->hash_lock);
> +		err = -ENODEV;
> +		if (po->pppoe_dev) {
> +			mtu = po->pppoe_dev->mtu;
> +			err = 0;
> +		}
> +		read_unlock_bh(&pn->hash_lock);
> +		if (err)
> +			break;
>  		err = -EFAULT;
> -		if (put_user(po->pppoe_dev->mtu -
> -			     sizeof(struct pppoe_hdr) -
> -			     PPP_HDRLEN,
> +		if (put_user(mtu - sizeof(struct pppoe_hdr) - PPP_HDRLEN,
>  			     (int __user *)arg))
>  			break;
>  		err = 0;
> @@ -761,13 +788,21 @@ static int pppoe_ioctl(struct socket *so
>  		if (!(sk->sk_state & PPPOX_CONNECTED))
>  			break;
>
> +		read_lock_bh(&pn->hash_lock);
> +		err = -ENODEV;
> +		if (po->pppoe_dev) {
> +			mtu = po->pppoe_dev->mtu;
> +			err = 0;
> +		}
> +		read_unlock_bh(&pn->hash_lock);
> +		if (err)
> +			break;
> +
>  		err = -EFAULT;
>  		if (get_user(val, (int __user *)arg))
>  			break;
>
> -		if (val < (po->pppoe_dev->mtu
> -			   - sizeof(struct pppoe_hdr)
> -			   - PPP_HDRLEN))
> +		if (val < (mtu - sizeof(struct pppoe_hdr) - PPP_HDRLEN))
>  			err = 0;
>  		else
>  			err = -EINVAL;
> @@ -839,10 +874,11 @@ static int pppoe_sendmsg(struct kiocb *i
>  	struct sk_buff *skb;
>  	struct sock *sk = sock->sk;
>  	struct pppox_sock *po = pppox_sk(sk);
> +	struct pppoe_net *pn = pppoe_pernet(sock_net(sk));
>  	int error;
>  	struct pppoe_hdr hdr;
>  	struct pppoe_hdr *ph;
> -	struct net_device *dev;
> +	struct net_device *dev = NULL;
>  	char *start;
>
>  	lock_sock(sk);
> @@ -856,18 +892,27 @@ static int pppoe_sendmsg(struct kiocb *i
>  	hdr.code = 0;
>  	hdr.sid = po->num;
>
> -	dev = po->pppoe_dev;
> +	read_lock_bh(&pn->hash_lock);
> +	error = -ENODEV;
> +	if (po->pppoe_dev) {
> +		dev = po->pppoe_dev;
> +		dev_hold(dev);
> +		error = 0;
> +	}
> +	read_unlock_bh(&pn->hash_lock);
> +	if (error)
> +		goto end;
>
>  	error = -EMSGSIZE;
>  	if (total_len > (dev->mtu + dev->hard_header_len))
> -		goto end;
> +		goto end_put;
>
>
>  	skb = sock_wmalloc(sk, total_len + dev->hard_header_len + 32,
>  			   0, GFP_KERNEL);
>  	if (!skb) {
>  		error = -ENOMEM;
> -		goto end;
> +		goto end_put;
>  	}
>
>  	/* Reserve space for headers. */
> @@ -885,7 +930,7 @@ static int pppoe_sendmsg(struct kiocb *i
>  	error = memcpy_fromiovec(start, m->msg_iov, total_len);
>  	if (error < 0) {
>  		kfree_skb(skb);
> -		goto end;
> +		goto end_put;
>  	}
>
>  	error = total_len;
> @@ -898,6 +943,8 @@ static int pppoe_sendmsg(struct kiocb *i
>
>  	dev_queue_xmit(skb);
>
> +end_put:
> +	dev_put(dev);
>  end:
>  	release_sock(sk);
>  	return error;
> @@ -911,21 +958,28 @@ end:
>  static int __pppoe_xmit(struct sock *sk, struct sk_buff *skb)
>  {
>  	struct pppox_sock *po = pppox_sk(sk);
> -	struct net_device *dev = po->pppoe_dev;
> +	struct pppoe_net *pn = pppoe_pernet(sock_net(sk));
> +	struct net_device *dev;
>  	struct pppoe_hdr *ph;
>  	int data_len = skb->len;
>
> -	if (sock_flag(sk, SOCK_DEAD) || !(sk->sk_state & PPPOX_CONNECTED))
> +	read_lock_bh(&pn->hash_lock);
> +	if (!po->pppoe_dev) {
> +		read_unlock_bh(&pn->hash_lock);
>  		goto abort;
> +	}
> +	dev = po->pppoe_dev;
> +	dev_hold(dev);
> +	read_unlock_bh(&pn->hash_lock);
>
> -	if (!dev)
> -		goto abort;
> +	if (sock_flag(sk, SOCK_DEAD) || !(sk->sk_state & PPPOX_CONNECTED))
> +		goto abort_put;
>
>  	/* Copy the data if there is no space for the header or if it's
>  	 * read-only.
>  	 */
>  	if (skb_cow_head(skb, sizeof(*ph) + dev->hard_header_len))
> -		goto abort;
> +		goto abort_put;
>
>  	__skb_push(skb, sizeof(*ph));
>  	skb_reset_network_header(skb);
> @@ -944,9 +998,11 @@ static int __pppoe_xmit(struct sock *sk,
>  			po->pppoe_pa.remote, NULL, data_len);
>
>  	dev_queue_xmit(skb);
> -
> +	dev_put(dev);
>  	return 1;
>
> +abort_put:
> +	dev_put(dev);
>  abort:
>  	kfree_skb(skb);
>  	return 1;