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Commit 403dfb58 authored by Oliver Neukum's avatar Oliver Neukum Committed by Greg Kroah-Hartman
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USB: usb-skeleton: usb anchor to implement flush 



This patch set introduces usb_anchor and uses it to implement all modern
APIs in the skeleton driver.

- proper error reporting in the skeleton driver
- implementation of flush()

Signed-off-by: default avatarOliver Neukum <oneukum@suse.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 51a2f077

drivers/usb/usb-skeleton.c

+65 −7
Original line number Diff line number Diff line
@@ -51,16 +51,20 @@ struct usb_skel { 
	struct usb_device	*udev;			/* the usb device for this device */

	struct usb_interface	*interface;		/* the interface for this device */

	struct semaphore	limit_sem;		/* limiting the number of writes in progress */

	struct usb_anchor	submitted;		/* in case we need to retract our submissions */

	unsigned char           *bulk_in_buffer;	/* the buffer to receive data */

	size_t			bulk_in_size;		/* the size of the receive buffer */

	__u8			bulk_in_endpointAddr;	/* the address of the bulk in endpoint */

	__u8			bulk_out_endpointAddr;	/* the address of the bulk out endpoint */

	int			errors;			/* the last request tanked */

	spinlock_t		err_lock;		/* lock for errors */

	struct kref		kref;

	struct mutex		io_mutex;		/* synchronize I/O with disconnect */

};

#define to_skel_dev(d) container_of(d, struct usb_skel, kref)



static struct usb_driver skel_driver;

static void skel_draw_down(struct usb_skel *dev);



static void skel_delete(struct kref *kref)

{
@@ -130,6 +134,30 @@ static int skel_release(struct inode *inode, struct file *file) 
	return 0;

}



static int skel_flush(struct file *file, fl_owner_t id)

{

	struct usb_skel *dev;

	int res;



	dev = (struct usb_skel *)file->private_data;

	if (dev == NULL)

		return -ENODEV;



	/* wait for io to stop */

	mutex_lock(&dev->io_mutex);

	skel_draw_down(dev);



	/* read out errors, leave subsequent opens a clean slate */

	spin_lock_irq(&dev->err_lock);

	res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0;

	dev->errors = 0;

	spin_unlock_irq(&dev->err_lock);



	mutex_unlock(&dev->io_mutex);



	return res;

}



static ssize_t skel_read(struct file *file, char *buffer, size_t count, loff_t *ppos)

{

	struct usb_skel *dev;
@@ -171,12 +199,16 @@ static void skel_write_bulk_callback(struct urb *urb) 
	dev = (struct usb_skel *)urb->context;



	/* sync/async unlink faults aren't errors */

	if (urb->status &&

	    !(urb->status == -ENOENT ||

	if (urb->status) {

		if(!(urb->status == -ENOENT ||

		    urb->status == -ECONNRESET ||

	      urb->status == -ESHUTDOWN)) {

		    urb->status == -ESHUTDOWN))

			err("%s - nonzero write bulk status received: %d",

			    __FUNCTION__, urb->status);



		spin_lock(&dev->err_lock);

		dev->errors = urb->status;

		spin_unlock(&dev->err_lock);

	}



	/* free up our allocated buffer */
@@ -205,6 +237,17 @@ static ssize_t skel_write(struct file *file, const char *user_buffer, size_t cou 
		goto exit;

	}



	spin_lock_irq(&dev->err_lock);

	if ((retval = dev->errors) < 0) {

		/* any error is reported once */

		dev->errors = 0;

		/* to preserve notifications about reset */

		retval = (retval == -EPIPE) ? retval : -EIO;

	}

	spin_unlock_irq(&dev->err_lock);

	if (retval < 0)

		goto error;



	/* create a urb, and a buffer for it, and copy the data to the urb */

	urb = usb_alloc_urb(0, GFP_KERNEL);

	if (!urb) {
@@ -236,13 +279,14 @@ static ssize_t skel_write(struct file *file, const char *user_buffer, size_t cou 
			  usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),

			  buf, writesize, skel_write_bulk_callback, dev);

	urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;

	usb_anchor_urb(urb, &dev->submitted);



	/* send the data out the bulk port */

	retval = usb_submit_urb(urb, GFP_KERNEL);

	mutex_unlock(&dev->io_mutex);

	if (retval) {

		err("%s - failed submitting write urb, error %d", __FUNCTION__, retval);

		goto error;

		goto error_unanchor;

	}



	/* release our reference to this urb, the USB core will eventually free it entirely */
@@ -251,6 +295,8 @@ static ssize_t skel_write(struct file *file, const char *user_buffer, size_t cou 


	return writesize;



error_unanchor:

	usb_unanchor_urb(urb);

error:

	if (urb) {

		usb_buffer_free(dev->udev, writesize, buf, urb->transfer_dma);
@@ -268,6 +314,7 @@ static const struct file_operations skel_fops = { 
	.write =	skel_write,

	.open =		skel_open,

	.release =	skel_release,

	.flush =	skel_flush,

};



/*
@@ -298,6 +345,8 @@ static int skel_probe(struct usb_interface *interface, const struct usb_device_i 
	kref_init(&dev->kref);

	sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);

	mutex_init(&dev->io_mutex);

	spin_lock_init(&dev->err_lock);

	init_usb_anchor(&dev->submitted);



	dev->udev = usb_get_dev(interface_to_usbdev(interface));

	dev->interface = interface;
@@ -377,6 +426,15 @@ static void skel_disconnect(struct usb_interface *interface) 
	info("USB Skeleton #%d now disconnected", minor);

}



static void skel_draw_down(struct usb_skel *dev)

{

	int time;



	time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);

	if (!time)

		usb_kill_anchored_urbs(&dev->submitted);

}



static struct usb_driver skel_driver = {

	.name =		"skeleton",

	.probe =	skel_probe,