vmbus: fix missing signaling in hv_signal_on_read()

[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@microsoft.com>
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index d596a07..8cc99de 100644 (file)
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -1521,11 +1521,11 @@ 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;