On Tuesday 16 December 2014 17:06:02 Benjamin Tissoires wrote:
> If a disconnect occurs while getting the actual name of the device
> (which can take several HID transactions), the name of the device will
> be the hid name, provided by the Unifying Receiver.
> This means that in some cases, the user space will see a different
> name that what it usually sees when there is no disconnect.
>
> We should store the name of the device in the struct hidpp. That way,
> if a disconnect occurs while we are accessing the name,
> hidpp_connect_event() can fail, and the input node is not created.
>
> The input node will be created only if we have a connection which
> lasts long enough to retrieve all the requested information:
> name, protocol, and specific configuration.
>
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
> ---
> drivers/hid/hid-logitech-hidpp.c | 31 ++++++++++++++++++++-----------
> 1 file changed, 20 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
> index c0fb5fe..4bc8714 100644
> --- a/drivers/hid/hid-logitech-hidpp.c
> +++ b/drivers/hid/hid-logitech-hidpp.c
> @@ -89,6 +89,7 @@ struct hidpp_device {
> struct hid_device *hid_dev;
> struct mutex send_mutex;
> void *send_receive_buf;
> + char *name;
> wait_queue_head_t wait;
> bool answer_available;
> u8 protocol_major;
> @@ -1087,6 +1088,7 @@ static void hidpp_input_close(struct input_dev *dev)
> static struct input_dev *hidpp_allocate_input(struct hid_device *hdev)
> {
> struct input_dev *input_dev = devm_input_allocate_device(&hdev->dev);
> + struct hidpp_device *hidpp = hid_get_drvdata(hdev);
>
> if (!input_dev)
> return NULL;
> @@ -1095,7 +1097,7 @@ static struct input_dev *hidpp_allocate_input(struct hid_device *hdev)
> input_dev->open = hidpp_input_open;
> input_dev->close = hidpp_input_close;
>
> - input_dev->name = hdev->name;
> + input_dev->name = hidpp->name;
> input_dev->phys = hdev->phys;
> input_dev->uniq = hdev->uniq;
> input_dev->id.bustype = hdev->bus;
> @@ -1137,22 +1139,28 @@ static void hidpp_connect_event(struct hidpp_device *hidpp)
> hid_info(hdev, "HID++ %u.%u device connected.\n",
> hidpp->protocol_major, hidpp->protocol_minor);
>
> + if (!hidpp->name || hidpp->name == hdev->name) {
Hm, is it ever possible that hidpp->name is NULL? probe sets the pointer
to an array (hdev->name). Defence in depth I guess, but perhaps a
comment could clarify this?
Otherwise the changes look OK. I have tested this situation:
1. Insert receiver
2. Return a HID++ version for the WTP.
3. Return -9 (ResourceError) for the device name feature request (via
the QEMU emulation).
4. Observe that this fails.
So maybe you could add a comment for the above and add these tags:
Reviewed-by: Peter Wu <peter@xxxxxxxxxxxxx>
Tested-by: Peter Wu <peter@xxxxxxxxxxxxx>
Kind regards,
Peter
> + name = hidpp_get_device_name(hidpp);
> + if (!name) {
> + hid_err(hdev,
> + "unable to retrieve the name of the device");
> + return;
> + }
> +
> + devm_name = devm_kasprintf(&hdev->dev, GFP_KERNEL, "%s", name);
> + kfree(name);
> + if (!devm_name)
> + return;
> +
> + hidpp->name = devm_name;
> + }
> +
> input = hidpp_allocate_input(hdev);
> if (!input) {
> hid_err(hdev, "cannot allocate new input device: %d\n", ret);
> return;
> }
>
> - name = hidpp_get_device_name(hidpp);
> - if (!name) {
> - hid_err(hdev, "unable to retrieve the name of the device");
> - } else {
> - devm_name = devm_kasprintf(&hdev->dev, GFP_KERNEL, "%s", name);
> - if (devm_name)
> - input->name = devm_name;
> - kfree(name);
> - }
> -
> hidpp_populate_input(hidpp, input, false);
>
> ret = input_register_device(input);
> @@ -1175,6 +1183,7 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id)
> return -ENOMEM;
>
> hidpp->hid_dev = hdev;
> + hidpp->name = hdev->name;
> hid_set_drvdata(hdev, hidpp);
>
> hidpp->quirks = id->driver_data;
>
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