Re: [PATCH 01/25] HID: break out hid_extract_field

From: Henrik Rydberg
Date: Mon Jan 28 2013 - 09:59:05 EST


Hi Benjamin,

> Breaking out this function allows third parties hid drivers to retrieve
> the data fields of a hid report in the raw_event callback.
>
> No functional changes, only exports the function.
>
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxx>
> ---
> drivers/hid/hid-core.c | 60 ++++++++++++++++++++++++++++++++++----------------
> include/linux/hid.h | 1 +
> 2 files changed, 42 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
> index 5ae2cb1..ea478f5 100644
> --- a/drivers/hid/hid-core.c
> +++ b/drivers/hid/hid-core.c
> @@ -962,6 +962,45 @@ static void implement(const struct hid_device *hid, __u8 *report,
> }
>
> /*
> + * Extract and allocate a data field from a little endian report (bit array).
> + */
> +
> +s32 *hid_extract_field(const struct hid_device *hid, struct hid_field *field,
> + __u8 *data)
> +{
> + unsigned n;
> + unsigned count = field->report_count;
> + unsigned offset = field->report_offset;
> + unsigned size = field->report_size;
> + __s32 min = field->logical_minimum;
> + __s32 max = field->logical_maximum;
> + __s32 *value;
> +
> + value = kmalloc(sizeof(__s32) * count, GFP_ATOMIC);
> + if (!value)
> + return value;
> +
> + for (n = 0; n < count; n++) {
> +
> + value[n] = min < 0 ?
> + snto32(extract(hid, data, offset + n * size, size),
> + size) :
> + extract(hid, data, offset + n * size, size);
> +
> + /* Ignore report if ErrorRollOver */
> + if (!(field->flags & HID_MAIN_ITEM_VARIABLE) &&
> + value[n] >= min && value[n] <= max &&
> + field->usage[value[n] - min].hid == HID_UP_KEYBOARD + 1) {
> + kfree(value);
> + return NULL;
> + }
> + }
> +
> + return value;
> +}
> +EXPORT_SYMBOL_GPL(hid_extract_field);
> +

I would rather see the extensive use of malloc go away than extend its
usage to drivers.

Thanks,
Henrik
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