Commit 0ca10122 authored by Oliver Neukum's avatar Oliver Neukum Committed by Greg Kroah-Hartman
Browse files

usb/misc/chaoskey: introduce an URB for asynchronous reads 



To allow for and clean handling of signals an URB is introduced.

Signed-off-by: default avatarOliver Neukum <oneukum@suse.com>
Signed-off-by: default avatarKeith Packard <keithp@keithp.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 0a15e24c

drivers/usb/misc/chaoskey.c

+65 −21
Original line number Diff line number Diff line
@@ -73,6 +73,8 @@ static const struct usb_device_id chaoskey_table[] = { 
};

MODULE_DEVICE_TABLE(usb, chaoskey_table);



static void chaos_read_callback(struct urb *urb);



/* Driver-local specific stuff */

struct chaoskey {

	struct usb_interface *interface;
@@ -80,7 +82,8 @@ struct chaoskey { 
	struct mutex lock;

	struct mutex rng_lock;

	int open;			/* open count */

	int present;			/* device not disconnected */

	bool present;			/* device not disconnected */

	bool reading;			/* ongoing IO */

	int size;			/* size of buf */

	int valid;			/* bytes of buf read */

	int used;			/* bytes of buf consumed */
@@ -88,6 +91,7 @@ struct chaoskey { 
	struct hwrng hwrng;		/* Embedded struct for hwrng */

	int hwrng_registered;		/* registered with hwrng API */

	wait_queue_head_t wait_q;	/* for timeouts */

	struct urb *urb;		/* for performing IO */

	char *buf;

};
@@ -95,6 +99,7 @@ static void chaoskey_free(struct chaoskey *dev) 
{

	if (dev) {

		usb_dbg(dev->interface, "free");

		usb_free_urb(dev->urb);

		kfree(dev->name);

		kfree(dev->buf);

		kfree(dev);
@@ -151,6 +156,19 @@ static int chaoskey_probe(struct usb_interface *interface, 
	if (dev->buf == NULL)

		goto out;



	dev->urb = usb_alloc_urb(0, GFP_KERNEL);



	if (!dev->urb)

		goto out;



	usb_fill_bulk_urb(dev->urb,

		udev,

		usb_rcvbulkpipe(udev, in_ep),

		dev->buf,

		size,

		chaos_read_callback,

		dev);



	/* Construct a name using the product and serial values. Each

	 * device needs a unique name for the hwrng code

	 */
@@ -237,6 +255,7 @@ static void chaoskey_disconnect(struct usb_interface *interface) 
	mutex_lock(&dev->lock);



	dev->present = 0;

	usb_poison_urb(dev->urb);



	if (!dev->open) {

		mutex_unlock(&dev->lock);
@@ -311,14 +330,33 @@ static int chaoskey_release(struct inode *inode, struct file *file) 
	return 0;

}



static void chaos_read_callback(struct urb *urb)

{

	struct chaoskey *dev = urb->context;

	int status = urb->status;



	usb_dbg(dev->interface, "callback status (%d)", status);



	if (status == 0)

		dev->valid = urb->actual_length;

	else

		dev->valid = 0;



	dev->used = 0;



	/* must be seen first before validity is announced */

	smp_wmb();



	dev->reading = false;

	wake_up(&dev->wait_q);

}



/* Fill the buffer. Called with dev->lock held

 */

static int _chaoskey_fill(struct chaoskey *dev)

{

	DEFINE_WAIT(wait);

	int result;

	int this_read;

	struct usb_device *udev = interface_to_usbdev(dev->interface);



	usb_dbg(dev->interface, "fill");
@@ -343,21 +381,31 @@ static int _chaoskey_fill(struct chaoskey *dev) 
		return result;

	}



	result = usb_bulk_msg(udev,

			      usb_rcvbulkpipe(udev, dev->in_ep),

			      dev->buf, dev->size, &this_read,

	dev->reading = true;

	result = usb_submit_urb(dev->urb, GFP_KERNEL);

	if (result < 0) {

		result = usb_translate_errors(result);

		dev->reading = false;

		goto out;

	}



	result = wait_event_interruptible_timeout(

		dev->wait_q,

		!dev->reading,

		NAK_TIMEOUT);



	if (result < 0)

		goto out;



	if (result == 0)

		result = -ETIMEDOUT;

	else

		result = dev->valid;

out:

	/* Let the device go back to sleep eventually */

	usb_autopm_put_interface(dev->interface);



	if (result == 0) {

		dev->valid = this_read;

		dev->used = 0;

	}



	usb_dbg(dev->interface, "bulk_msg result %d this_read %d",

		result, this_read);

	usb_dbg(dev->interface, "read %d bytes", dev->valid);



	return result;

}
@@ -395,13 +443,7 @@ static ssize_t chaoskey_read(struct file *file, 
			goto bail;

		if (dev->valid == dev->used) {

			result = _chaoskey_fill(dev);

			if (result) {

				mutex_unlock(&dev->lock);

				goto bail;

			}



			/* Read returned zero bytes */

			if (dev->used == dev->valid) {

			if (result < 0) {

				mutex_unlock(&dev->lock);

				goto bail;

			}
@@ -435,6 +477,8 @@ static ssize_t chaoskey_read(struct file *file, 
		return read_count;

	}

	usb_dbg(dev->interface, "empty read, result %d", result);

	if (result == -ETIMEDOUT)

		result = -EAGAIN;

	return result;

}