staging: comedi: don't hijack hardware device private data

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>

diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
index 9465bce..ab9f5ed 100644 (file)
--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -2207,6 +2207,7 @@ int comedi_alloc_board_minor(struct device *hardware_device)
                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 minor)
        }
 }
 
+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)
 {

diff --git a/drivers/staging/comedi/comedidev.h b/drivers/staging/comedi/comedidev.h
index 7a0d4bc..00d3c65 100644 (file)
--- 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

diff --git a/drivers/staging/comedi/drivers.c b/drivers/staging/comedi/drivers.c
index db1fd63..538b568 100644 (file)
--- a/drivers/staging/comedi/drivers.c
+++ b/drivers/staging/comedi/drivers.c
@@ -823,25 +823,14 @@ static int comedi_auto_config(struct device *hardware_device,
        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 device *hardware_device,
        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)

diff --git a/drivers/staging/comedi/internal.h b/drivers/staging/comedi/internal.h
index 434ce34..4208fb4 100644 (file)
--- 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_subdevice *s,
               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);