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Subject[ 120/128] staging: comedi: dont hijack hardware device private data
3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ian Abbott <abbotti@mev.co.uk>

commit c43435d7722134ed1fda58ce1025f41029bd58ad upstream.

comedi_auto_config() associates a Comedi minor device number with an
auto-configured hardware device and comedi_auto_unconfig() disassociates
it. Currently, these use the hardware device's private data pointer to
point to some allocated storage holding the minor device number. This
is a bit of a waste of the hardware device's private data pointer,
preventing it from being used for something more useful by the low-level
comedi device drivers. For example, it would make more sense if
comedi_usb_auto_config() was passed a pointer to the struct
usb_interface instead of the struct usb_device, but this cannot be done
currently because the low-level comedi drivers already use the private
data pointer in the struct usb_interface for something more useful.

This patch stops the comedi core hijacking the hardware device's private
data pointer. Instead, comedi_auto_config() stores a pointer to the
hardware device's struct device in the struct comedi_device_file_info
associated with the minor device number, and comedi_auto_unconfig()
calls new function comedi_find_board_minor() to recover the minor device
number associated with the hardware device.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/staging/comedi/comedi_fops.c | 18 ++++++++++++++++++
drivers/staging/comedi/comedidev.h | 1 +
drivers/staging/comedi/drivers.c | 34 ++++++++++------------------------
drivers/staging/comedi/internal.h | 1 +
4 files changed, 30 insertions(+), 24 deletions(-)

--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -2207,6 +2207,7 @@ int comedi_alloc_board_minor(struct devi
kfree(info);
return -ENOMEM;
}
+ info->hardware_device = hardware_device;
comedi_device_init(info->device);
spin_lock_irqsave(&comedi_file_info_table_lock, flags);
for (i = 0; i < COMEDI_NUM_BOARD_MINORS; ++i) {
@@ -2295,6 +2296,23 @@ void comedi_free_board_minor(unsigned mi
}
}

+int comedi_find_board_minor(struct device *hardware_device)
+{
+ int minor;
+ struct comedi_device_file_info *info;
+
+ for (minor = 0; minor < COMEDI_NUM_BOARD_MINORS; minor++) {
+ spin_lock(&comedi_file_info_table_lock);
+ info = comedi_file_info_table[minor];
+ if (info && info->hardware_device == hardware_device) {
+ spin_unlock(&comedi_file_info_table_lock);
+ return minor;
+ }
+ spin_unlock(&comedi_file_info_table_lock);
+ }
+ return -ENODEV;
+}
+
int comedi_alloc_subdevice_minor(struct comedi_device *dev,
struct comedi_subdevice *s)
{
--- a/drivers/staging/comedi/comedidev.h
+++ b/drivers/staging/comedi/comedidev.h
@@ -234,6 +234,7 @@ struct comedi_device_file_info {
struct comedi_device *device;
struct comedi_subdevice *read_subdevice;
struct comedi_subdevice *write_subdevice;
+ struct device *hardware_device;
};

#ifdef CONFIG_COMEDI_DEBUG
--- a/drivers/staging/comedi/drivers.c
+++ b/drivers/staging/comedi/drivers.c
@@ -823,25 +823,14 @@ static int comedi_auto_config(struct dev
int minor;
struct comedi_device_file_info *dev_file_info;
int retval;
- unsigned *private_data = NULL;

- if (!comedi_autoconfig) {
- dev_set_drvdata(hardware_device, NULL);
+ if (!comedi_autoconfig)
return 0;
- }

minor = comedi_alloc_board_minor(hardware_device);
if (minor < 0)
return minor;

- private_data = kmalloc(sizeof(unsigned), GFP_KERNEL);
- if (private_data == NULL) {
- retval = -ENOMEM;
- goto cleanup;
- }
- *private_data = minor;
- dev_set_drvdata(hardware_device, private_data);
-
dev_file_info = comedi_get_device_file_info(minor);

memset(&it, 0, sizeof(it));
@@ -854,25 +843,22 @@ static int comedi_auto_config(struct dev
retval = comedi_device_attach(dev_file_info->device, &it);
mutex_unlock(&dev_file_info->device->mutex);

-cleanup:
- if (retval < 0) {
- kfree(private_data);
+ if (retval < 0)
comedi_free_board_minor(minor);
- }
return retval;
}

static void comedi_auto_unconfig(struct device *hardware_device)
{
- unsigned *minor = (unsigned *)dev_get_drvdata(hardware_device);
- if (minor == NULL)
- return;
-
- BUG_ON(*minor >= COMEDI_NUM_BOARD_MINORS);
+ int minor;

- comedi_free_board_minor(*minor);
- dev_set_drvdata(hardware_device, NULL);
- kfree(minor);
+ if (hardware_device == NULL)
+ return;
+ minor = comedi_find_board_minor(hardware_device);
+ if (minor < 0)
+ return;
+ BUG_ON(minor >= COMEDI_NUM_BOARD_MINORS);
+ comedi_free_board_minor(minor);
}

int comedi_pci_auto_config(struct pci_dev *pcidev, const char *board_name)
--- a/drivers/staging/comedi/internal.h
+++ b/drivers/staging/comedi/internal.h
@@ -7,6 +7,7 @@ int insn_inval(struct comedi_device *dev
struct comedi_insn *insn, unsigned int *data);
int comedi_alloc_board_minor(struct device *hardware_device);
void comedi_free_board_minor(unsigned minor);
+int comedi_find_board_minor(struct device *hardware_device);
void comedi_reset_async_buf(struct comedi_async *async);
int comedi_buf_alloc(struct comedi_device *dev, struct comedi_subdevice *s,
unsigned long new_size);



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