Re: [PATCH v2 char-misc 1/1] Drivers: hv: vmbus: Fix ring buffer signaling

[Stephen Hemminger]

On Fri, 16 Feb 2018 23:05:33 +0000
Michael Kelley <mhkelley@xxxxxxxxxxx> wrote:

> Fix bugs in signaling the Hyper-V host when freeing space in the
> host->guest ring buffer:
> 
> 1. The interrupt_mask must not be used to determine whether to signal
>    on the host->guest ring buffer
> 2. The ring buffer write_index must be read (via hv_get_bytes_to_write)
>    *after* pending_send_sz is read in order to avoid a race condition
> 3. Comparisons with pending_send_sz must treat the "equals" case as
>    not-enough-space
> 4. Don't signal if the pending_send_sz feature is not present. Older
>    versions of Hyper-V that don't implement this feature will poll.
> 
> Fixes: 03bad714a161 ("vmbus: more host signalling avoidance")
> Signed-off-by: Michael Kelley <mhkelley@xxxxxxxxxxx>

Signed-off-by: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>