Staging: hv: vmbus: Check for events before messages

The Windows team has informed us that on Windows guests on Hyper-V,
they check for events before messages. They also recommended that we do
the same. This patch addresses this.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/staging/hv/vmbus_drv.c b/drivers/staging/hv/vmbus_drv.c
index b5e06d68f0582dbedd019bcc1d3af6af063b8e43..cd43ddd3cc836ea7e0c896a805c1f937e56eb59e 100644 (file)
--- a/drivers/staging/hv/vmbus_drv.c
+++ b/drivers/staging/hv/vmbus_drv.c
@@ -442,14 +442,11 @@ static irqreturn_t vmbus_isr(int irq, void *dev_id)
        union hv_synic_event_flags *event;
        bool handled = false;
 
-       page_addr = hv_context.synic_message_page[cpu];
-       msg = (struct hv_message *)page_addr + VMBUS_MESSAGE_SINT;
-
-       /* Check if there are actual msgs to be process */
-       if (msg->header.message_type != HVMSG_NONE) {
-               handled = true;
-               tasklet_schedule(&msg_dpc);
-       }
+       /*
+        * Check for events before checking for messages. This is the order
+        * in which events and messages are checked in Windows guests on
+        * Hyper-V, and the Windows team suggested we do the same.
+        */
 
        page_addr = hv_context.synic_event_page[cpu];
        event = (union hv_synic_event_flags *)page_addr + VMBUS_MESSAGE_SINT;
@@ -460,6 +457,15 @@ static irqreturn_t vmbus_isr(int irq, void *dev_id)
                tasklet_schedule(&event_dpc);
        }
 
+       page_addr = hv_context.synic_message_page[cpu];
+       msg = (struct hv_message *)page_addr + VMBUS_MESSAGE_SINT;
+
+       /* Check if there are actual msgs to be processed */
+       if (msg->header.message_type != HVMSG_NONE) {
+               handled = true;
+               tasklet_schedule(&msg_dpc);
+       }
+
        if (handled)
                return IRQ_HANDLED;
        else