> The dev_rdesc member of the hid_device structure is meant to store the
> original
> report descriptor received from the device, but it is currently passed to any
> report_fixup method before it is copied to the rdesc member. This patch uses a
> temporary buffer to shield dev_rdesc from the side effects of many HID
> drivers'
> report_fixup implementations.
>
> usbhid's hid_post_reset checks the report descriptor currently returned by the
> device against a descriptor that may have been modified by a driver's
> report_fixup method. That leaves some devices nonfunctional after a resume,
> with
> a "reset_resume error 1" reported. This patch checks the new descriptor
> against
> the unmodified dev_rdesc instead and uses the original, instead of modified,
> report size.
>
> BugLink: http://bugs.launchpad.net/bugs/1049623
> Signed-off-by: Kevin Daughtridge <[email protected]>
> ---
Looks like it will work, thank you Kevin. The comments below are just
suggestions, I am fine with the patch as is.
> drivers/hid/hid-core.c | 16 +++++++++++++---
> drivers/hid/usbhid/hid-core.c | 6 +++---
> 2 files changed, 16 insertions(+), 6 deletions(-)
>
> Changed in this version: added a temporary buffer to work around report_fixup
> inconsistencies; using dev_rsize instead of rsize to allocate and read new
> descriptor.
>
> diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
> index 8bcd168..5de3bb3 100644
> --- a/drivers/hid/hid-core.c
> +++ b/drivers/hid/hid-core.c
> @@ -757,6 +757,7 @@ int hid_open_report(struct hid_device *device)
> struct hid_item item;
> unsigned int size;
> __u8 *start;
> + __u8 *buf;
It is sad to have to add a temporary here.
> __u8 *end;
> int ret;
> static int (*dispatch_type[])(struct hid_parser *parser,
> @@ -775,12 +776,21 @@ int hid_open_report(struct hid_device *device)
> return -ENODEV;
> size = device->dev_rsize;
>
> + buf = kmemdup(start, size, GFP_KERNEL);
> + if (buf == NULL)
> + return -ENOMEM;
> +
> if (device->driver->report_fixup)
> - start = device->driver->report_fixup(device, start, &size);
> + start = device->driver->report_fixup(device, buf, &size);
> + else
> + start = buf;
>
> - device->rdesc = kmemdup(start, size, GFP_KERNEL);
> - if (device->rdesc == NULL)
> + start = kmemdup(start, size, GFP_KERNEL);
> + kfree(buf);
Changing the semantics of the callback did not seem appealing, but it
does not prevent us from using our own version internally. So, how
about something like this:
static __u8 *hid_alloc_rdesc(struct hid_device *devicew,
const __u8 *start, unsigned int *size)
{
__u8 *rdesc = kmemdup(start, *size, GFP_KERNEL);
if (rdesc && device->driver->report_fixup) {
__u8 *tmp = device->driver->report_fixup(device, rdesc, size);
if (tmp != rdesc) {
tmp = kmemdup(tmp, *size, GFP_KERNEL);
kfree(rdesc);
rdesc = tmp;
}
}
return rdesc;
}
> + if (start == NULL)
> return -ENOMEM;
> +
> + device->rdesc = start;
> device->rsize = size;
>
> parser = vzalloc(sizeof(struct hid_parser));
> diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
> index dedd8e4..8e0c4bf94 100644
> --- a/drivers/hid/usbhid/hid-core.c
> +++ b/drivers/hid/usbhid/hid-core.c
> @@ -1415,20 +1415,20 @@ static int hid_post_reset(struct usb_interface *intf)
> * configuration descriptors passed, we already know that
> * the size of the HID report descriptor has not changed.
> */
> - rdesc = kmalloc(hid->rsize, GFP_KERNEL);
> + rdesc = kmalloc(hid->dev_rsize, GFP_KERNEL);
> if (!rdesc) {
> dbg_hid("couldn't allocate rdesc memory (post_reset)\n");
> return 1;
> }
> status = hid_get_class_descriptor(dev,
> interface->desc.bInterfaceNumber,
> - HID_DT_REPORT, rdesc, hid->rsize);
> + HID_DT_REPORT, rdesc, hid->dev_rsize);
> if (status < 0) {
> dbg_hid("reading report descriptor failed (post_reset)\n");
> kfree(rdesc);
> return 1;
> }
> - status = memcmp(rdesc, hid->rdesc, hid->rsize);
> + status = memcmp(rdesc, hid->dev_rdesc, hid->dev_rsize);
> kfree(rdesc);
> if (status != 0) {
> dbg_hid("report descriptor changed\n");
Thanks,
Henrik
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