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Commit 07778393 authored by Ian Abbott's avatar Ian Abbott Committed by Greg Kroah-Hartman
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staging: comedi: pre-lock mutex on creation of comedi device 



Return from `comedi_alloc_board_minor()` with the mutex of the created
`struct comedi_device` pre-locked.  This allows further initialization
by the caller without the worry of something getting in there first.

`comedi_auto_config()` no longer needs to check if the device is already
"attached" since whatever was trying to attach the device would need to
have locked the mutex first.

Signed-off-by: default avatarIan Abbott <abbotti@mev.co.uk>
Reviewed-by: default avatarH Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 7638ffcb

drivers/staging/comedi/comedi_fops.c

+7 −0
Original line number Diff line number Diff line
@@ -2274,6 +2274,7 @@ static void comedi_device_cleanup(struct comedi_device *dev) 
	mutex_destroy(&dev->mutex);

}



/* Note: the ->mutex is pre-locked on successful return */

struct comedi_device *comedi_alloc_board_minor(struct device *hardware_device)

{

	struct comedi_file_info *info;
@@ -2292,6 +2293,7 @@ struct comedi_device *comedi_alloc_board_minor(struct device *hardware_device) 
	info->device = dev;

	info->hardware_device = hardware_device;

	comedi_device_init(dev);

	mutex_lock(&dev->mutex);

	spin_lock(&comedi_file_info_table_lock);

	for (i = 0; i < COMEDI_NUM_BOARD_MINORS; ++i) {

		if (comedi_file_info_table[i] == NULL) {
@@ -2301,6 +2303,7 @@ struct comedi_device *comedi_alloc_board_minor(struct device *hardware_device) 
	}

	spin_unlock(&comedi_file_info_table_lock);

	if (i == COMEDI_NUM_BOARD_MINORS) {

		mutex_unlock(&dev->mutex);

		comedi_device_cleanup(dev);

		kfree(dev);

		kfree(info);
@@ -2314,6 +2317,7 @@ struct comedi_device *comedi_alloc_board_minor(struct device *hardware_device) 
		dev->class_dev = csdev;

	dev_set_drvdata(csdev, info);



	/* Note: dev->mutex needs to be unlocked by the caller. */

	return dev;

}
@@ -2485,6 +2489,9 @@ static int __init comedi_init(void) 
			unregister_chrdev_region(MKDEV(COMEDI_MAJOR, 0),

						 COMEDI_NUM_MINORS);

			return PTR_ERR(dev);

		} else {

			/* comedi_alloc_board_minor() locked the mutex */

			mutex_unlock(&dev->mutex);

		}

	}

drivers/staging/comedi/drivers.c

+2 −4
Original line number Diff line number Diff line
@@ -429,11 +429,9 @@ int comedi_auto_config(struct device *hardware_device, 
	comedi_dev = comedi_alloc_board_minor(hardware_device);

	if (IS_ERR(comedi_dev))

		return PTR_ERR(comedi_dev);

	/* Note: comedi_alloc_board_minor() locked comedi_dev->mutex. */



	mutex_lock(&comedi_dev->mutex);

	if (comedi_dev->attached)

		ret = -EBUSY;

	else if (!try_module_get(driver->module))

	if (!try_module_get(driver->module))

		ret = -EIO;

	else {

		comedi_set_hw_dev(comedi_dev, hardware_device);