From: Paul Durrant <paul.durrant@citrix.com>
Date: Tue, 24 Jul 2018 14:46:22 +0000 (+0100)
Subject: Back-port rsp_event manipulation changes from master
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=db0323253ebdd478c959f16992cdf28d59014c70;p=pvdrivers%2Fwin%2Fxenvbd.git

Back-port rsp_event manipulation changes from master

Rather than updating rsp_event at the end of every poll, the code in
master sets it to req_prod_pvt during submission to attempt to defer events
until the last request has been processed.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
---

diff --git a/src/xenvbd/blockring.c b/src/xenvbd/blockring.c
index 7cf5c84..b4688e7 100644
--- a/src/xenvbd/blockring.c
+++ b/src/xenvbd/blockring.c
@@ -549,7 +549,6 @@ BlockRingPoll(
         KeMemoryBarrier();
 
         BlockRing->FrontRing.rsp_cons = rsp_cons;
-        BlockRing->SharedRing->rsp_event = rsp_cons + 1;
     }
 
 done:
@@ -575,7 +574,7 @@ BlockRingSubmit(
     req = RING_GET_REQUEST(&BlockRing->FrontRing, BlockRing->FrontRing.req_prod_pvt);
     __BlockRingInsert(BlockRing, Request, req);
     KeMemoryBarrier();
-    ++BlockRing->FrontRing.req_prod_pvt;
+    BlockRing->SharedRing->rsp_event = ++BlockRing->FrontRing.req_prod_pvt;
 
     RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&BlockRing->FrontRing, Notify);
     KeReleaseSpinLock(&BlockRing->Lock, Irql);