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    Subject[ 169/171] staging: comedi: dont hijack hardware device private data
    Date
    3.4-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>

    ---
    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
    @@ -2210,6 +2210,7 @@ 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) {
    @@ -2298,6 +2299,23 @@ 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
    @@ -822,25 +822,14 @@ 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));
    @@ -853,25 +842,22 @@ 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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