[ATM]: deregistration removes device from atm_devs list immediately

atm_dev_deregister() removes device from atm_dev list immediately to
prevent operations on a phantom device.  Decision to free device based
only on ->refcnt  now. Remove shutdown_atm_dev() use atm_dev_deregister()
instead.  atm_dev_deregister() also asynchronously releases all vccs
related to device.

Signed-off-by: Stanislaw Gruszka <stf_xl@wp.pl>
Signed-off-by: Chas Williams <chas@cmf.nrl.navy.mil>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/atm/atmtcp.c

@@ -246,10 +246,6 @@ static void atmtcp_c_close(struct atm_vcc *vcc)
 {
 	struct atm_dev *atmtcp_dev;
 	struct atmtcp_dev_data *dev_data;
-	struct sock *s;
-	struct hlist_node *node;
-	struct atm_vcc *walk;
-	int i;
 
 	atmtcp_dev = (struct atm_dev *) vcc->dev_data;
 	dev_data = PRIV(atmtcp_dev);
@@ -257,20 +253,8 @@ static void atmtcp_c_close(struct atm_vcc *vcc)
 	if (dev_data->persist) return;
 	atmtcp_dev->dev_data = NULL;
 	kfree(dev_data);
-	shutdown_atm_dev(atmtcp_dev);
+	atm_dev_deregister(atmtcp_dev);
 	vcc->dev_data = NULL;
-	read_lock(&vcc_sklist_lock);
-	for(i = 0; i < VCC_HTABLE_SIZE; ++i) {
-		struct hlist_head *head = &vcc_hash[i];
-
-		sk_for_each(s, node, head) {
-			walk = atm_sk(s);
-			if (walk->dev != atmtcp_dev)
-				continue;
-			wake_up(s->sk_sleep);
-		}
-	}
-	read_unlock(&vcc_sklist_lock);
 	module_put(THIS_MODULE);
 }
 
@@ -450,7 +434,7 @@ static int atmtcp_remove_persistent(int itf)
 	if (PRIV(dev)->vcc) return 0;
 	kfree(dev_data);
 	atm_dev_put(dev);
-	shutdown_atm_dev(dev);
+	atm_dev_deregister(dev);
 	return 0;
 }
 

drivers/usb/atm/usbatm.c

@@ -879,7 +879,7 @@ static int usbatm_atm_init(struct usbatm_data *instance)
 
  fail:
 	instance->atm_dev = NULL;
-	shutdown_atm_dev(atm_dev); /* usbatm_atm_dev_close will eventually be called */
+	atm_dev_deregister(atm_dev); /* usbatm_atm_dev_close will eventually be called */
 	return ret;
 }
 
@@ -1164,7 +1164,7 @@ void usbatm_usb_disconnect(struct usb_interface *intf)
 
 	/* ATM finalize */
 	if (instance->atm_dev)
-		shutdown_atm_dev(instance->atm_dev);
+		atm_dev_deregister(instance->atm_dev);
 
 	usbatm_put_instance(instance);	/* taken in usbatm_usb_probe */
 }

include/linux/atmdev.h

@@ -274,7 +274,7 @@ enum {
 
 
 enum {
-	ATM_DF_CLOSE,		/* close device when last VCC is closed */
+	ATM_DF_REMOVED,		/* device was removed from atm_devs list */
 };
 
 
@@ -415,7 +415,6 @@ struct atm_dev *atm_dev_register(const char *type,const struct atmdev_ops *ops,
     int number,unsigned long *flags); /* number == -1: pick first available */
 struct atm_dev *atm_dev_lookup(int number);
 void atm_dev_deregister(struct atm_dev *dev);
-void shutdown_atm_dev(struct atm_dev *dev);
 void vcc_insert_socket(struct sock *sk);
 
 
@@ -457,11 +456,12 @@ static inline void atm_dev_hold(struct atm_dev *dev)
 
 static inline void atm_dev_put(struct atm_dev *dev)
 {
-	atomic_dec(&dev->refcnt);
-
-	if ((atomic_read(&dev->refcnt) == 1) &&
-	    test_bit(ATM_DF_CLOSE,&dev->flags))
-		shutdown_atm_dev(dev);
+	if (atomic_dec_and_test(&dev->refcnt)) {
+		BUG_ON(!test_bit(ATM_DF_REMOVED, &dev->flags));
+		if (dev->ops->dev_close)
+			dev->ops->dev_close(dev);
+		kfree(dev);
+	}
 }
 
 

net/atm/common.c

@@ -221,6 +221,29 @@ void vcc_release_async(struct atm_vcc *vcc, int reply)
 EXPORT_SYMBOL(vcc_release_async);
 
 
+void atm_dev_release_vccs(struct atm_dev *dev)
+{
+	int i;
+
+	write_lock_irq(&vcc_sklist_lock);
+	for (i = 0; i < VCC_HTABLE_SIZE; i++) {
+		struct hlist_head *head = &vcc_hash[i];
+		struct hlist_node *node, *tmp;
+		struct sock *s;
+		struct atm_vcc *vcc;
+
+		sk_for_each_safe(s, node, tmp, head) {
+			vcc = atm_sk(s);
+			if (vcc->dev == dev) {
+				vcc_release_async(vcc, -EPIPE);
+				sk_del_node_init(s);
+			}
+		}
+	}
+	write_unlock_irq(&vcc_sklist_lock);
+}
+
+
 static int adjust_tp(struct atm_trafprm *tp,unsigned char aal)
 {
 	int max_sdu;
@@ -332,12 +355,13 @@ static int __vcc_connect(struct atm_vcc *vcc, struct atm_dev *dev, short vpi,
 		return -EINVAL;
 	if (vci > 0 && vci < ATM_NOT_RSV_VCI && !capable(CAP_NET_BIND_SERVICE))
 		return -EPERM;
-	error = 0;
+	error = -ENODEV;
 	if (!try_module_get(dev->ops->owner))
-		return -ENODEV;
+		return error;
 	vcc->dev = dev;
 	write_lock_irq(&vcc_sklist_lock);
-	if ((error = find_ci(vcc, &vpi, &vci))) {
+	if (test_bit(ATM_DF_REMOVED, &dev->flags) || 
+	    (error = find_ci(vcc, &vpi, &vci))) {
 		write_unlock_irq(&vcc_sklist_lock);
 		goto fail_module_put;
 	}

net/atm/common.h

@@ -47,4 +47,6 @@ static inline void atm_proc_exit(void)
 /* SVC */
 int svc_change_qos(struct atm_vcc *vcc,struct atm_qos *qos);
 
+void atm_dev_release_vccs(struct atm_dev *dev);
+
 #endif

net/atm/resources.c

@@ -70,6 +70,7 @@ struct atm_dev *atm_dev_lookup(int number)
 	return dev;
 }
 
+
 struct atm_dev *atm_dev_register(const char *type, const struct atmdev_ops *ops,
 				 int number, unsigned long *flags)
 {
@@ -123,37 +124,22 @@ struct atm_dev *atm_dev_register(const char *type, const struct atmdev_ops *ops,
 
 void atm_dev_deregister(struct atm_dev *dev)
 {
-	unsigned long warning_time;
-
-	atm_proc_dev_deregister(dev);
+	BUG_ON(test_bit(ATM_DF_REMOVED, &dev->flags));
+	set_bit(ATM_DF_REMOVED, &dev->flags);
 
+	/*
+	 * if we remove current device from atm_devs list, new device 
+	 * with same number can appear, such we need deregister proc, 
+	 * release async all vccs and remove them from vccs list too
+	 */
 	down(&atm_dev_mutex);
 	list_del(&dev->dev_list);
 	up(&atm_dev_mutex);
 
-        warning_time = jiffies;
-        while (atomic_read(&dev->refcnt) != 1) {
-                msleep(250);
-                if ((jiffies - warning_time) > 10 * HZ) {
-                        printk(KERN_EMERG "atm_dev_deregister: waiting for "
-                               "dev %d to become free. Usage count = %d\n",
-                               dev->number, atomic_read(&dev->refcnt));
-                        warning_time = jiffies;
-                }
-        }
+	atm_dev_release_vccs(dev);
+	atm_proc_dev_deregister(dev);
 
-	kfree(dev);
-}
-
-void shutdown_atm_dev(struct atm_dev *dev)
-{
-	if (atomic_read(&dev->refcnt) > 1) {
-		set_bit(ATM_DF_CLOSE, &dev->flags);
-		return;
-	}
-	if (dev->ops->dev_close)
-		dev->ops->dev_close(dev);
-	atm_dev_deregister(dev);
+	atm_dev_put(dev);
 }
 
 
@@ -433,4 +419,3 @@ void *atm_dev_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 EXPORT_SYMBOL(atm_dev_register);
 EXPORT_SYMBOL(atm_dev_deregister);
 EXPORT_SYMBOL(atm_dev_lookup);
-EXPORT_SYMBOL(shutdown_atm_dev);