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staging: comedi: pre-lock mutex on creation of comedi device

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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: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ian Abbott 2013-04-04 14:58:51 +01:00 committed by Greg Kroah-Hartman
parent 7638ffcb50
commit 07778393d9
2 changed files with 9 additions and 4 deletions
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7
drivers/staging/comedi/comedi_fops.c
View File

@ -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);
}
}

6
drivers/staging/comedi/drivers.c
View File

@ -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);