Merge git://git.infradead.org/users/dwmw2/atm

David Woodhouse says:

====================
This is the result of pulling on the thread started by Krzysztof Mazur's
original patch 'pppoatm: don't send frames to destroyed vcc'.

Various problems in the pppoatm and br2684 code are solved, some of which
were easily triggered and would panic the kernel.
====================

Signed-off-by: David S. Miller <[e-mail]>

drivers/atm/solos-pci.c

···
 static uint32_t fpga_tx(struct solos_card *);
 static irqreturn_t solos_irq(int irq, void *dev_id);
 static struct atm_vcc* find_vcc(struct atm_dev *dev, short vpi, int vci);
-static int list_vccs(int vci);
 static int atm_init(struct solos_card *, struct device *);
 static void atm_remove(struct solos_card *);
 static int send_command(struct solos_card *card, int dev, const char *buf, size_t size);
···
 						dev_warn(&card->dev->dev, "Received packet for unknown VPI.VCI %d.%d on port %d\n",
 							 le16_to_cpu(header->vpi), le16_to_cpu(header->vci),
 							 port);
-					continue;
+					dev_kfree_skb_any(skb);
+					break;
 				}
 				atm_charge(vcc, skb->truesize);
 				vcc->push(vcc, skb);
···
 	return vcc;
 }
 
-static int list_vccs(int vci)
-{
-	struct hlist_head *head;
-	struct atm_vcc *vcc;
-	struct hlist_node *node;
-	struct sock *s;
-	int num_found = 0;
-	int i;
-
-	read_lock(&vcc_sklist_lock);
-	if (vci != 0){
-		head = &vcc_hash[vci & (VCC_HTABLE_SIZE -1)];
-		sk_for_each(s, node, head) {
-			num_found ++;
-			vcc = atm_sk(s);
-			printk(KERN_DEBUG "Device: %d Vpi: %d Vci: %d\n",
-			       vcc->dev->number,
-			       vcc->vpi,
-			       vcc->vci);
-		}
-	} else {
-		for(i = 0; i < VCC_HTABLE_SIZE; i++){
-			head = &vcc_hash[i];
-			sk_for_each(s, node, head) {
-				num_found ++;
-				vcc = atm_sk(s);
-				printk(KERN_DEBUG "Device: %d Vpi: %d Vci: %d\n",
-				       vcc->dev->number,
-				       vcc->vpi,
-				       vcc->vci);
-			}
-		}
-	}
-	read_unlock(&vcc_sklist_lock);
-	return num_found;
-}
-
-
 static int popen(struct atm_vcc *vcc)
 {
 	struct solos_card *card = vcc->dev->dev_data;
···
 		return -EINVAL;
 	}
 
-	skb = alloc_skb(sizeof(*header), GFP_ATOMIC);
+	skb = alloc_skb(sizeof(*header), GFP_KERNEL);
 	if (!skb) {
 		if (net_ratelimit())
 			dev_warn(&card->dev->dev, "Failed to allocate sk_buff in popen()\n");
···
 
 	set_bit(ATM_VF_ADDR, &vcc->flags);
 	set_bit(ATM_VF_READY, &vcc->flags);
-	list_vccs(0);
-
 
 	return 0;
 }
···
 static void pclose(struct atm_vcc *vcc)
 {
 	struct solos_card *card = vcc->dev->dev_data;
-	struct sk_buff *skb;
+	unsigned char port = SOLOS_CHAN(vcc->dev);
+	struct sk_buff *skb, *tmpskb;
 	struct pkt_hdr *header;
 
-	skb = alloc_skb(sizeof(*header), GFP_ATOMIC);
+	/* Remove any yet-to-be-transmitted packets from the pending queue */
+	spin_lock(&card->tx_queue_lock);
+	skb_queue_walk_safe(&card->tx_queue[port], skb, tmpskb) {
+		if (SKB_CB(skb)->vcc == vcc) {
+			skb_unlink(skb, &card->tx_queue[port]);
+			solos_pop(vcc, skb);
+		}
+	}
+	spin_unlock(&card->tx_queue_lock);
+
+	skb = alloc_skb(sizeof(*header), GFP_KERNEL);
 	if (!skb) {
 		dev_warn(&card->dev->dev, "Failed to allocate sk_buff in pclose()\n");
 		return;
···
 	header->vci = cpu_to_le16(vcc->vci);
 	header->type = cpu_to_le16(PKT_PCLOSE);
 
-	fpga_queue(card, SOLOS_CHAN(vcc->dev), skb, NULL);
+	skb_get(skb);
+	fpga_queue(card, port, skb, NULL);
 
-	clear_bit(ATM_VF_ADDR, &vcc->flags);
-	clear_bit(ATM_VF_READY, &vcc->flags);
+	if (!wait_event_timeout(card->param_wq, !skb_shared(skb), 5 * HZ))
+		dev_warn(&card->dev->dev,
+			 "Timeout waiting for VCC close on port %d\n", port);
+
+	dev_kfree_skb(skb);
 
 	/* Hold up vcc_destroy_socket() (our caller) until solos_bh() in the
 	   tasklet has finished processing any incoming packets (and, more to
 	   the point, using the vcc pointer). */
 	tasklet_unlock_wait(&card->tlet);
+
+	clear_bit(ATM_VF_ADDR, &vcc->flags);
+
 	return;
 }
 
···
 			if (vcc) {
 				atomic_inc(&vcc->stats->tx);
 				solos_pop(vcc, oldskb);
-			} else
+			} else {
 				dev_kfree_skb_irq(oldskb);
-
+				wake_up(&card->param_wq);
+			}
 		}
 	}
 	/* For non-DMA TX, write the 'TX start' bit for all four ports simultaneously */
···
 		card->atmdev[i]->phy_data = (void *)(unsigned long)i;
 		atm_dev_signal_change(card->atmdev[i], ATM_PHY_SIG_FOUND);
 
-		skb = alloc_skb(sizeof(*header), GFP_ATOMIC);
+		skb = alloc_skb(sizeof(*header), GFP_KERNEL);
 		if (!skb) {
 			dev_warn(&card->dev->dev, "Failed to allocate sk_buff in atm_init()\n");
 			continue;
···
 
 static int __init solos_pci_init(void)
 {
+	BUILD_BUG_ON(sizeof(struct solos_skb_cb) > sizeof(((struct sk_buff *)0)->cb));
+
 	printk(KERN_INFO "Solos PCI Driver Version %s\n", VERSION);
 	return pci_register_driver(&fpga_driver);
 }

include/linux/atmdev.h

···
 	struct atm_dev	*dev;		/* device back pointer */
 	struct atm_qos	qos;		/* QOS */
 	struct atm_sap	sap;		/* SAP */
+	void (*release_cb)(struct atm_vcc *vcc); /* release_sock callback */
 	void (*push)(struct atm_vcc *vcc,struct sk_buff *skb);
 	void (*pop)(struct atm_vcc *vcc,struct sk_buff *skb); /* optional */
 	int (*push_oam)(struct atm_vcc *vcc,void *cell);
···
 	void		*dev_data;	/* per-device data */
 	void		*proto_data;	/* per-protocol data */
 	struct k_atm_aal_stats *stats;	/* pointer to AAL stats group */
+	struct module *owner;		/* owner of ->push function */
 	/* SVC part --- may move later ------------------------------------- */
 	short		itf;		/* interface number */
 	struct sockaddr_atmsvc local;

net/atm/br2684.c

···
 	/* keep old push, pop functions for chaining */
 	void (*old_push)(struct atm_vcc *vcc, struct sk_buff *skb);
 	void (*old_pop)(struct atm_vcc *vcc, struct sk_buff *skb);
+	void (*old_release_cb)(struct atm_vcc *vcc);
+	struct module *old_owner;
 	enum br2684_encaps encaps;
 	struct list_head brvccs;
 #ifdef CONFIG_ATM_BR2684_IPFILTER
···
 	return !atmvcc->send(atmvcc, skb);
 }
 
+static void br2684_release_cb(struct atm_vcc *atmvcc)
+{
+	struct br2684_vcc *brvcc = BR2684_VCC(atmvcc);
+
+	if (atomic_read(&brvcc->qspace) > 0)
+		netif_wake_queue(brvcc->device);
+
+	if (brvcc->old_release_cb)
+		brvcc->old_release_cb(atmvcc);
+}
+
 static inline struct br2684_vcc *pick_outgoing_vcc(const struct sk_buff *skb,
 						   const struct br2684_dev *brdev)
 {
···
 {
 	struct br2684_dev *brdev = BRPRIV(dev);
 	struct br2684_vcc *brvcc;
+	struct atm_vcc *atmvcc;
+	netdev_tx_t ret = NETDEV_TX_OK;
 
 	pr_debug("skb_dst(skb)=%p\n", skb_dst(skb));
 	read_lock(&devs_lock);
···
 		dev->stats.tx_carrier_errors++;
 		/* netif_stop_queue(dev); */
 		dev_kfree_skb(skb);
-		read_unlock(&devs_lock);
-		return NETDEV_TX_OK;
+		goto out_devs;
 	}
+	atmvcc = brvcc->atmvcc;
+
+	bh_lock_sock(sk_atm(atmvcc));
+
+	if (test_bit(ATM_VF_RELEASED, &atmvcc->flags) ||
+	    test_bit(ATM_VF_CLOSE, &atmvcc->flags) ||
+	    !test_bit(ATM_VF_READY, &atmvcc->flags)) {
+		dev->stats.tx_dropped++;
+		dev_kfree_skb(skb);
+		goto out;
+	}
+
+	if (sock_owned_by_user(sk_atm(atmvcc))) {
+		netif_stop_queue(brvcc->device);
+		ret = NETDEV_TX_BUSY;
+		goto out;
+	}
+
 	if (!br2684_xmit_vcc(skb, dev, brvcc)) {
 		/*
 		 * We should probably use netif_*_queue() here, but that
···
 		dev->stats.tx_errors++;
 		dev->stats.tx_fifo_errors++;
 	}
+ out:
+	bh_unlock_sock(sk_atm(atmvcc));
+ out_devs:
 	read_unlock(&devs_lock);
-	return NETDEV_TX_OK;
+	return ret;
 }
 
 /*
···
 	list_del(&brvcc->brvccs);
 	write_unlock_irq(&devs_lock);
 	brvcc->atmvcc->user_back = NULL;	/* what about vcc->recvq ??? */
+	brvcc->atmvcc->release_cb = brvcc->old_release_cb;
 	brvcc->old_push(brvcc->atmvcc, NULL);	/* pass on the bad news */
+	module_put(brvcc->old_owner);
 	kfree(brvcc);
-	module_put(THIS_MODULE);
 }
 
 /* when AAL5 PDU comes in: */
···
 	brvcc->encaps = (enum br2684_encaps)be.encaps;
 	brvcc->old_push = atmvcc->push;
 	brvcc->old_pop = atmvcc->pop;
+	brvcc->old_release_cb = atmvcc->release_cb;
+	brvcc->old_owner = atmvcc->owner;
 	barrier();
 	atmvcc->push = br2684_push;
 	atmvcc->pop = br2684_pop;
+	atmvcc->release_cb = br2684_release_cb;
+	atmvcc->owner = THIS_MODULE;
 
 	/* initialize netdev carrier state */
 	if (atmvcc->dev->signal == ATM_PHY_SIG_LOST)
···
 			return -ENOIOCTLCMD;
 		if (!capable(CAP_NET_ADMIN))
 			return -EPERM;
-		if (cmd == ATM_SETBACKEND)
+		if (cmd == ATM_SETBACKEND) {
+			if (sock->state != SS_CONNECTED)
+				return -EINVAL;
 			return br2684_regvcc(atmvcc, argp);
-		else
+		} else {
 			return br2684_create(argp);
+		}
 #ifdef CONFIG_ATM_BR2684_IPFILTER
 	case BR2684_SETFILT:
 		if (atmvcc->push != br2684_push)

net/atm/common.c

···
 	rcu_read_unlock();
 }
 
+static void vcc_release_cb(struct sock *sk)
+{
+	struct atm_vcc *vcc = atm_sk(sk);
+
+	if (vcc->release_cb)
+		vcc->release_cb(vcc);
+}
+
 static struct proto vcc_proto = {
 	.name	  = "VCC",
 	.owner	  = THIS_MODULE,
 	.obj_size = sizeof(struct atm_vcc),
+	.release_cb = vcc_release_cb,
 };
 
 int vcc_create(struct net *net, struct socket *sock, int protocol, int family)
···
 	atomic_set(&sk->sk_rmem_alloc, 0);
 	vcc->push = NULL;
 	vcc->pop = NULL;
+	vcc->owner = NULL;
 	vcc->push_oam = NULL;
+	vcc->release_cb = NULL;
 	vcc->vpi = vcc->vci = 0; /* no VCI/VPI yet */
 	vcc->atm_options = vcc->aal_options = 0;
 	sk->sk_destruct = vcc_sock_destruct;
···
 			vcc->dev->ops->close(vcc);
 		if (vcc->push)
 			vcc->push(vcc, NULL); /* atmarpd has no push */
+		module_put(vcc->owner);
 
 		while ((skb = skb_dequeue(&sk->sk_receive_queue)) != NULL) {
 			atm_return(vcc, skb->truesize);

net/atm/pppoatm.c

···
 	struct atm_vcc	*atmvcc;	/* VCC descriptor */
 	void (*old_push)(struct atm_vcc *, struct sk_buff *);
 	void (*old_pop)(struct atm_vcc *, struct sk_buff *);
+	void (*old_release_cb)(struct atm_vcc *);
+	struct module *old_owner;
 					/* keep old push/pop for detaching */
 	enum pppoatm_encaps encaps;
 	atomic_t inflight;
···
 	ppp_output_wakeup((struct ppp_channel *) arg);
 }
 
+static void pppoatm_release_cb(struct atm_vcc *atmvcc)
+{
+	struct pppoatm_vcc *pvcc = atmvcc_to_pvcc(atmvcc);
+
+	/*
+	 * As in pppoatm_pop(), it's safe to clear the BLOCKED bit here because
+	 * the wakeup *can't* race with pppoatm_send(). They both hold the PPP
+	 * channel's ->downl lock. And the potential race with *setting* it,
+	 * which leads to the double-check dance in pppoatm_may_send(), doesn't
+	 * exist here. In the sock_owned_by_user() case in pppoatm_send(), we
+	 * set the BLOCKED bit while the socket is still locked. We know that
+	 * ->release_cb() can't be called until that's done.
+	 */
+	if (test_and_clear_bit(BLOCKED, &pvcc->blocked))
+		tasklet_schedule(&pvcc->wakeup_tasklet);
+	if (pvcc->old_release_cb)
+		pvcc->old_release_cb(atmvcc);
+}
 /*
  * This gets called every time the ATM card has finished sending our
  * skb.  The ->old_pop will take care up normal atm flow control,
···
 	pvcc = atmvcc_to_pvcc(atmvcc);
 	atmvcc->push = pvcc->old_push;
 	atmvcc->pop = pvcc->old_pop;
+	atmvcc->release_cb = pvcc->old_release_cb;
 	tasklet_kill(&pvcc->wakeup_tasklet);
 	ppp_unregister_channel(&pvcc->chan);
 	atmvcc->user_back = NULL;
 	kfree(pvcc);
-	/* Gee, I hope we have the big kernel lock here... */
-	module_put(THIS_MODULE);
 }
 
 /* Called when an AAL5 PDU comes in */
···
 	struct pppoatm_vcc *pvcc = atmvcc_to_pvcc(atmvcc);
 	pr_debug("\n");
 	if (skb == NULL) {			/* VCC was closed */
+		struct module *module;
+
 		pr_debug("removing ATMPPP VCC %p\n", pvcc);
+		module = pvcc->old_owner;
 		pppoatm_unassign_vcc(atmvcc);
 		atmvcc->push(atmvcc, NULL);	/* Pass along bad news */
+		module_put(module);
 		return;
 	}
 	atm_return(atmvcc, skb->truesize);
···
 	ppp_input_error(&pvcc->chan, 0);
 }
 
-static inline int pppoatm_may_send(struct pppoatm_vcc *pvcc, int size)
+static int pppoatm_may_send(struct pppoatm_vcc *pvcc, int size)
 {
 	/*
 	 * It's not clear that we need to bother with using atm_may_send()
···
 static int pppoatm_send(struct ppp_channel *chan, struct sk_buff *skb)
 {
 	struct pppoatm_vcc *pvcc = chan_to_pvcc(chan);
+	struct atm_vcc *vcc;
+	int ret;
+
 	ATM_SKB(skb)->vcc = pvcc->atmvcc;
 	pr_debug("(skb=0x%p, vcc=0x%p)\n", skb, pvcc->atmvcc);
 	if (skb->data[0] == '\0' && (pvcc->flags & SC_COMP_PROT))
 		(void) skb_pull(skb, 1);
+
+	vcc = ATM_SKB(skb)->vcc;
+	bh_lock_sock(sk_atm(vcc));
+	if (sock_owned_by_user(sk_atm(vcc))) {
+		/*
+		 * Needs to happen (and be flushed, hence test_and_) before we unlock
+		 * the socket. It needs to be seen by the time our ->release_cb gets
+		 * called.
+		 */
+		test_and_set_bit(BLOCKED, &pvcc->blocked);
+		goto nospace;
+	}
+	if (test_bit(ATM_VF_RELEASED, &vcc->flags) ||
+	    test_bit(ATM_VF_CLOSE, &vcc->flags) ||
+	    !test_bit(ATM_VF_READY, &vcc->flags)) {
+		bh_unlock_sock(sk_atm(vcc));
+		kfree_skb(skb);
+		return DROP_PACKET;
+	}
+
 	switch (pvcc->encaps) {		/* LLC encapsulation needed */
 	case e_llc:
 		if (skb_headroom(skb) < LLC_LEN) {
···
 			}
 			consume_skb(skb);
 			skb = n;
-			if (skb == NULL)
+			if (skb == NULL) {
+				bh_unlock_sock(sk_atm(vcc));
 				return DROP_PACKET;
+			}
 		} else if (!pppoatm_may_send(pvcc, skb->truesize))
 			goto nospace;
 		memcpy(skb_push(skb, LLC_LEN), pppllc, LLC_LEN);
···
 			goto nospace;
 		break;
 	case e_autodetect:
+		bh_unlock_sock(sk_atm(vcc));
 		pr_debug("Trying to send without setting encaps!\n");
 		kfree_skb(skb);
 		return 1;
···
 	ATM_SKB(skb)->atm_options = ATM_SKB(skb)->vcc->atm_options;
 	pr_debug("atm_skb(%p)->vcc(%p)->dev(%p)\n",
 		 skb, ATM_SKB(skb)->vcc, ATM_SKB(skb)->vcc->dev);
-	return ATM_SKB(skb)->vcc->send(ATM_SKB(skb)->vcc, skb)
+	ret = ATM_SKB(skb)->vcc->send(ATM_SKB(skb)->vcc, skb)
 	    ? DROP_PACKET : 1;
+	bh_unlock_sock(sk_atm(vcc));
+	return ret;
 nospace:
+	bh_unlock_sock(sk_atm(vcc));
 	/*
 	 * We don't have space to send this SKB now, but we might have
 	 * already applied SC_COMP_PROT compression, so may need to undo
···
 	atomic_set(&pvcc->inflight, NONE_INFLIGHT);
 	pvcc->old_push = atmvcc->push;
 	pvcc->old_pop = atmvcc->pop;
+	pvcc->old_owner = atmvcc->owner;
+	pvcc->old_release_cb = atmvcc->release_cb;
 	pvcc->encaps = (enum pppoatm_encaps) be.encaps;
 	pvcc->chan.private = pvcc;
 	pvcc->chan.ops = &pppoatm_ops;
···
 	atmvcc->user_back = pvcc;
 	atmvcc->push = pppoatm_push;
 	atmvcc->pop = pppoatm_pop;
+	atmvcc->release_cb = pppoatm_release_cb;
 	__module_get(THIS_MODULE);
+	atmvcc->owner = THIS_MODULE;
 
 	/* re-process everything received between connection setup and
 	   backend setup */
···
 			return -ENOIOCTLCMD;
 		if (!capable(CAP_NET_ADMIN))
 			return -EPERM;
+		if (sock->state != SS_CONNECTED)
+			return -EINVAL;
 		return pppoatm_assign_vcc(atmvcc, argp);
 		}
 	case PPPIOCGCHAN: