Commit 121e287c authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
Browse files

usb-skeleton: don't submit URBs after disconnection 



This patch (as712b) is a slight revision of one submitted earlier.  It
fixes the usb-skeleton example driver so that it won't try to submit
URBs after skel_disconnect() has returned.  This could cause errors, if
the driver was unbound and then a different driver was bound to the
device.  It also fixes a couple of small bugs in the skel_write()
routine.

The revised patch uses a slightly different test, suggested by Dave
Brownell, for determining whether to free a transfer buffer.  It's a
little clearer than the earlier version.


Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 349710c3

drivers/usb/usb-skeleton.c

+33 −7
Original line number Diff line number Diff line 
/*

 * USB Skeleton driver - 2.0

 * USB Skeleton driver - 2.1

 *

 * Copyright (C) 2001-2004 Greg Kroah-Hartman (greg@kroah.com)

 *
@@ -8,8 +8,7 @@ 
 *	published by the Free Software Foundation, version 2.

 *

 * This driver is based on the 2.6.3 version of drivers/usb/usb-skeleton.c 

 * but has been rewritten to be easy to read and use, as no locks are now

 * needed anymore.

 * but has been rewritten to be easier to read and use.

 *

 */
@@ -21,6 +20,7 @@ 
#include <linux/kref.h>

#include <asm/uaccess.h>

#include <linux/usb.h>

#include <linux/mutex.h>





/* Define these values to match your devices */
@@ -52,6 +52,7 @@ struct usb_skel { 
	__u8			bulk_in_endpointAddr;	/* the address of the bulk in endpoint */

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

	struct kref		kref;

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

};

#define to_skel_dev(d) container_of(d, struct usb_skel, kref)
@@ -120,6 +121,12 @@ static ssize_t skel_read(struct file *file, char *buffer, size_t count, loff_t * 


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



	mutex_lock(&dev->io_mutex);

	if (!dev->interface) {		/* disconnect() was called */

		retval = -ENODEV;

		goto exit;

	}



	/* do a blocking bulk read to get data from the device */

	retval = usb_bulk_msg(dev->udev,

			      usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr),
@@ -135,6 +142,8 @@ static ssize_t skel_read(struct file *file, char *buffer, size_t count, loff_t * 
			retval = bytes_read;

	}



exit:

	mutex_unlock(&dev->io_mutex);

	return retval;

}
@@ -179,6 +188,12 @@ static ssize_t skel_write(struct file *file, const char *user_buffer, size_t cou 
		goto exit;

	}



	mutex_lock(&dev->io_mutex);

	if (!dev->interface) {		/* disconnect() was called */

		retval = -ENODEV;

		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) {
@@ -213,13 +228,18 @@ static ssize_t skel_write(struct file *file, const char *user_buffer, size_t cou 
	/* release our reference to this urb, the USB core will eventually free it entirely */

	usb_free_urb(urb);



exit:

	mutex_unlock(&dev->io_mutex);

	return writesize;



error:

	if (urb) {

		usb_buffer_free(dev->udev, writesize, buf, urb->transfer_dma);

		usb_free_urb(urb);

	}

	mutex_unlock(&dev->io_mutex);

	up(&dev->limit_sem);



exit:

	return retval;

}
@@ -258,6 +278,7 @@ 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);



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

	dev->interface = interface;
@@ -334,6 +355,11 @@ static void skel_disconnect(struct usb_interface *interface) 
	/* give back our minor */

	usb_deregister_dev(interface, &skel_class);



	/* prevent more I/O from starting */

	mutex_lock(&dev->io_mutex);

	dev->interface = NULL;

	mutex_unlock(&dev->io_mutex);



	unlock_kernel();



	/* decrement our usage count */

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