firewire: Use only a wait queue and terminate poll and read on device removal.

Drop the event list semaphore and only use the wait queue and the list
to synchronize queue access.  Break out of a poll or read whenever
the device is disconnected.
Signed-off-by: Kristian Høgsberg <krh@redhat.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

drivers/firewire/fw-device-cdev.c

@@ -76,7 +76,6 @@ struct client {
 	struct list_head request_list;
 	u32 request_serial;
 	struct list_head event_list;
-	struct semaphore event_list_sem;
 	wait_queue_head_t wait;
 
 	struct fw_iso_context *iso_context;
@@ -114,7 +113,6 @@ static int fw_device_op_open(struct inode *inode, struct file *file)
 
 	client->device = fw_device_get(device);
 	INIT_LIST_HEAD(&client->event_list);
-	sema_init(&client->event_list_sem, 0);
 	INIT_LIST_HEAD(&client->handler_list);
 	INIT_LIST_HEAD(&client->request_list);
 	spin_lock_init(&client->lock);
@@ -142,38 +140,41 @@ static void queue_event(struct client *client, struct event *event,
 	spin_lock_irqsave(&client->lock, flags);
 
 	list_add_tail(&event->link, &client->event_list);
-
-	up(&client->event_list_sem);
 	wake_up_interruptible(&client->wait);
 
 	spin_unlock_irqrestore(&client->lock, flags);
 }
 
-static int dequeue_event(struct client *client, char __user *buffer, size_t count)
+static int
+dequeue_event(struct client *client, char __user *buffer, size_t count)
 {
 	unsigned long flags;
 	struct event *event;
 	size_t size, total;
-	int i, retval = -EFAULT;
+	int i, retval;
 
-	if (down_interruptible(&client->event_list_sem) < 0)
-		return -EINTR;
+	retval = wait_event_interruptible(client->wait,
+					  !list_empty(&client->event_list) ||
+					  fw_device_is_shutdown(client->device));
+	if (retval < 0)
+		return retval;
 
-	spin_lock_irqsave(&client->lock, flags);
+	if (list_empty(&client->event_list) &&
+		       fw_device_is_shutdown(client->device))
+		return -ENODEV;
 
+	spin_lock_irqsave(&client->lock, flags);
 	event = container_of(client->event_list.next, struct event, link);
 	list_del(&event->link);
-
 	spin_unlock_irqrestore(&client->lock, flags);
 
-	if (buffer == NULL)
-		goto out;
-
 	total = 0;
 	for (i = 0; i < ARRAY_SIZE(event->v) && total < count; i++) {
 		size = min(event->v[i].size, count - total);
-		if (copy_to_user(buffer + total, event->v[i].data, size))
+		if (copy_to_user(buffer + total, event->v[i].data, size)) {
+			retval = -EFAULT;
 			goto out;
+		}
 		total += size;
 	}
 	retval = total;
@@ -208,6 +209,22 @@ fill_bus_reset_event(struct fw_cdev_event_bus_reset *event,
 	event->generation    = card->generation;
 }
 
+static void
+for_each_client(struct fw_device *device,
+		void (*callback)(struct client *client))
+{
+	struct fw_card *card = device->card;
+	struct client *c;
+	unsigned long flags;
+
+	spin_lock_irqsave(&card->lock, flags);
+
+	list_for_each_entry(c, &device->client_list, link)
+		callback(c);
+
+	spin_unlock_irqrestore(&card->lock, flags);
+}
+
 static void
 queue_bus_reset_event(struct client *client)
 {
@@ -228,16 +245,17 @@ queue_bus_reset_event(struct client *client)
 
 void fw_device_cdev_update(struct fw_device *device)
 {
-	struct fw_card *card = device->card;
-	struct client *c;
-	unsigned long flags;
-
-	spin_lock_irqsave(&card->lock, flags);
+	for_each_client(device, queue_bus_reset_event);
+}
 
-	list_for_each_entry(c, &device->client_list, link)
-		queue_bus_reset_event(c);
+static void wake_up_client(struct client *client)
+{
+	wake_up_interruptible(&client->wait);
+}
 
-	spin_unlock_irqrestore(&card->lock, flags);
+void fw_device_cdev_remove(struct fw_device *device)
+{
+	for_each_client(device, wake_up_client);
 }
 
 static int ioctl_get_info(struct client *client, void __user *arg)
@@ -731,8 +749,9 @@ static int fw_device_op_mmap(struct file *file, struct vm_area_struct *vma)
 static int fw_device_op_release(struct inode *inode, struct file *file)
 {
 	struct client *client = file->private_data;
-	struct address_handler *h, *next;
+	struct address_handler *h, *next_h;
 	struct request *r, *next_r;
+	struct event *e, *next_e;
 	unsigned long flags;
 
 	if (client->buffer.pages)
@@ -741,7 +760,7 @@ static int fw_device_op_release(struct inode *inode, struct file *file)
 	if (client->iso_context)
 		fw_iso_context_destroy(client->iso_context);
 
-	list_for_each_entry_safe(h, next, &client->handler_list, link) {
+	list_for_each_entry_safe(h, next_h, &client->handler_list, link) {
 		fw_core_remove_address_handler(&h->handler);
 		kfree(h);
 	}
@@ -755,8 +774,8 @@ static int fw_device_op_release(struct inode *inode, struct file *file)
 	/* TODO: wait for all transactions to finish so
 	 * complete_transaction doesn't try to queue up responses
 	 * after we free client. */
-	while (!list_empty(&client->event_list))
-		dequeue_event(client, NULL, 0);
+	list_for_each_entry_safe(e, next_e, &client->event_list, link)
+		kfree(e);
 
 	spin_lock_irqsave(&client->device->card->lock, flags);
 	list_del(&client->link);
@@ -771,13 +790,16 @@ static int fw_device_op_release(struct inode *inode, struct file *file)
 static unsigned int fw_device_op_poll(struct file *file, poll_table * pt)
 {
 	struct client *client = file->private_data;
+	unsigned int mask = 0;
 
 	poll_wait(file, &client->wait, pt);
 
+	if (fw_device_is_shutdown(client->device))
+		mask |= POLLHUP | POLLERR;
 	if (!list_empty(&client->event_list))
-		return POLLIN | POLLRDNORM;
-	else
-		return 0;
+		mask |= POLLIN | POLLRDNORM;
+
+	return mask;
 }
 
 const struct file_operations fw_device_ops = {

drivers/firewire/fw-device.c

@@ -453,6 +453,7 @@ static void fw_device_shutdown(struct work_struct *work)
 	idr_remove(&fw_device_idr, minor);
 	up_write(&fw_bus_type.subsys.rwsem);
 
+	fw_device_cdev_remove(device);
 	device_remove_file(&device->device, &config_rom_attribute);
 	device_for_each_child(&device->device, NULL, shutdown_unit);
 	device_unregister(&device->device);

drivers/firewire/fw-device.h

@@ -53,11 +53,18 @@ fw_device(struct device *dev)
 	return container_of(dev, struct fw_device, device);
 }
 
+static inline int
+fw_device_is_shutdown(struct fw_device *device)
+{
+	return atomic_read(&device->state) == FW_DEVICE_SHUTDOWN;
+}
+
 struct fw_device *fw_device_get(struct fw_device *device);
 void fw_device_put(struct fw_device *device);
 int fw_device_enable_phys_dma(struct fw_device *device);
 
 void fw_device_cdev_update(struct fw_device *device);
+void fw_device_cdev_remove(struct fw_device *device);
 
 struct fw_device *fw_device_from_devt(dev_t devt);
 extern int fw_cdev_major;