From 288fa3e022eb85fa151e0f9bcd15caeb81679af6 Mon Sep 17 00:00:00 2001 From: "K. Y. Srinivasan" <kys@microsoft.com> Date: Fri, 29 Mar 2013 14:30:38 -0700 Subject: Drivers: hv: vmbus: Fix a bug in hv_need_to_signal() As part of updating the vmbus protocol, the function hv_need_to_signal() was introduced. This functions helps optimize signalling from guest to host. The newly added memory barrier is needed to ensure that we correctly decide when to signal the host. Signed-off-by: K. Y. Srinivasan <kys@microsoft.com> Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com> Reported-by: Olaf Hering <olh@suse.de> Cc: Stable <stable@vger.kernel.org> (V3.8+) Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- drivers/hv/ring_buffer.c | 1 + 1 file changed, 1 insertion(+) (limited to 'drivers/hv') diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c index cafa72f..d6fbb577 100644 --- a/drivers/hv/ring_buffer.c +++ b/drivers/hv/ring_buffer.c @@ -71,6 +71,7 @@ u32 hv_end_read(struct hv_ring_buffer_info *rbi) static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi) { + smp_mb(); if (rbi->ring_buffer->interrupt_mask) return false; -- cgit v1.1