4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dexuan Cui <decui@xxxxxxxxxxxxx> [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@xxxxxxxxxxxxx> Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx> Signed-off-by: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- Hi Greg, as we discussed, I'm resending this patch, and please only apply it to linux-4.9.y (i.e. v4.9.57 as of today). include/linux/hyperv.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/include/linux/hyperv.h +++ b/include/linux/hyperv.h @@ -1521,11 +1521,11 @@ static inline void hv_signal_on_read(st 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;