[xenial][PATCH] vmbus: fix missing signaling in hv_signal_on_read()

[Marcelo Henrique Cerri]

On Mon, May 13, 2019 at 11:42:35AM -0300, Marcelo Henrique Cerri wrote:
> From: Dexuan Cui <decui at microsoft.com>
> 
> BugLink: http://bugs.launchpad.net/bugs/1826416
> 
> [Fixes upstream in a much larger set of patches that are not worth backporting
> to 4.9 - gregkh]
> 
> When the space available before start of reading (cached_write_sz)
> is the same as the host required space (pending_sz), we need to
> still signal host.
> 
> Fixes: 433e19cf33d3 ("Drivers: hv: vmbus: finally fix hv_need_to_signal_on_read()")
> 
> Signed-off-by: John Starks <jon.Starks at microsoft.com>
> Signed-off-by: Dexuan Cui <decui at microsoft.com>
> Signed-off-by: Stephen Hemminger <sthemmin at microsoft.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
> (cherry picked from commit 13c5e97701091f9b02ded0c68809f8a6b08c747a)

s/cherry picked from/cherry picked from stable 4.9.x/

We have several upstream patches for hyper-v applied on our 4.4.

> Signed-off-by: Marcelo Henrique Cerri <marcelo.cerri at canonical.com>
> ---
>  include/linux/hyperv.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
> index c92a083bcf16..f55a4c0c1475 100644
> --- a/include/linux/hyperv.h
> +++ b/include/linux/hyperv.h
> @@ -1520,11 +1520,11 @@ static inline  void hv_signal_on_read(struct vmbus_channel *channel)
>  
>  	cur_write_sz = hv_get_bytes_to_write(rbi);
>  
> -	if (cur_write_sz < pending_sz)
> +	if (cur_write_sz <= pending_sz)
>  		return;
>  
>  	cached_write_sz = hv_get_cached_bytes_to_write(rbi);
> -	if (cached_write_sz < pending_sz)
> +	if (cached_write_sz <= pending_sz)
>  		vmbus_setevent(channel);
>  
>  	return;
> -- 
> 2.20.1
> 

-- 
Regards,
Marcelo

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