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

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

[Stephen Hemminger]

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@microsoft.com>
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
---
This patch is for 4.13 (and stable).
A different fix is needed for linux-next.

 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 e09fc8290c2f..080a0797c6f3 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -1515,11 +1515,11 @@ 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);
 }
 
-- 
2.11.0

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

[Greg KH]

On Wed, Aug 16, 2017 at 08:49:46AM -0700, Stephen Hemminger wrote:
> 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@microsoft.com>
> Signed-off-by: Dexuan Cui <decui@microsoft.com>
> Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
> ---
> This patch is for 4.13 (and stable).
> A different fix is needed for linux-next.

Is there a fix for this in Linus's tree?  If so, what's the git commit
id?  We need to wait for that until I can take it in -stable.

thanks,

greg k-h

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

[Stephen Hemminger]

On Wed, 16 Aug 2017 09:10:40 -0700
Greg KH <gregkh@linuxfoundation.org> wrote:

> On Wed, Aug 16, 2017 at 08:49:46AM -0700, Stephen Hemminger wrote:
> > 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@microsoft.com>
> > Signed-off-by: Dexuan Cui <decui@microsoft.com>
> > Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
> > ---
> > This patch is for 4.13 (and stable).
> > A different fix is needed for linux-next.  
> 
> Is there a fix for this in Linus's tree?  If so, what's the git commit
> id?  We need to wait for that until I can take it in -stable.

There is no commit yet in Linus's tree. Was submitting for both Linus
and stable. Wasn't sure about the timing since 4.13 might close before he gets to it.