Re: [PATCH v2 4/5] HID: hv: Remove dependencies on PAGE_SIZE for ring buffer

From: Vitaly Kuznetsov
Date: Wed Jun 12 2019 - 06:45:08 EST


Maya Nakamura <m.maya.nakamura@xxxxxxxxx> writes:

> Define the ring buffer size as a constant expression because it should
> not depend on the guest page size.
>
> Signed-off-by: Maya Nakamura <m.maya.nakamura@xxxxxxxxx>
> ---
> drivers/hid/hid-hyperv.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/hid/hid-hyperv.c b/drivers/hid/hid-hyperv.c
> index d3311d714d35..e8b154fa38e2 100644
> --- a/drivers/hid/hid-hyperv.c
> +++ b/drivers/hid/hid-hyperv.c
> @@ -112,8 +112,8 @@ struct synthhid_input_report {
>
> #pragma pack(pop)
>
> -#define INPUTVSC_SEND_RING_BUFFER_SIZE (10*PAGE_SIZE)
> -#define INPUTVSC_RECV_RING_BUFFER_SIZE (10*PAGE_SIZE)
> +#define INPUTVSC_SEND_RING_BUFFER_SIZE (40 * 1024)
> +#define INPUTVSC_RECV_RING_BUFFER_SIZE (40 * 1024)
>

My understanding is that this size is pretty arbitrary and as I see you
use it for hyperv-keyboard.c as well. It may make sense to have a
define, something like HYPERV_STD_RINGBUFFER_SIZE.

>
> enum pipe_prot_msg_type {

--
Vitaly