From d36f2fda1257b946b5d210a63abde2db186849f4 Mon Sep 17 00:00:00 2001
From: Hussein Elnawawy <hussein.elnawawy@gmail.com>
Date: Fri, 21 Feb 2020 16:36:15 -0500
Subject: [PATCH] mem-ruby: Checkpoint from MOESI_hammer Ruby hangs

Fix MOESI_hammer checkpoint hanging.
The function markRemoved() should be called before hitCallback(),
not after it. The reason is that hitCallback() checks if draining is
complete based on the value of "m_outstanding_count". And since
markRemoved() is responsible for decrementing "m_outstanding_count",
hitCallback() does not see that there are no outstanding requests.

Reported by: Timothy Hayes
Jira: https://gem5.atlassian.net/browse/GEM5-331
Change-Id: I14c34be79843b172ae994ab1792fe4ce6cf5cf6e
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/25683
Reviewed-by: Timothy Hayes <timothy.hayes@arm.com>
Reviewed-by: John Alsop <johnathan.alsop@amd.com>
Maintainer: Bradford Beckmann <brad.beckmann@amd.com>
Tested-by: kokoro <noreply+kokoro@google.com>
---
 src/mem/ruby/system/Sequencer.cc | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/mem/ruby/system/Sequencer.cc b/src/mem/ruby/system/Sequencer.cc
index a90523e76..f81578700 100644
--- a/src/mem/ruby/system/Sequencer.cc
+++ b/src/mem/ruby/system/Sequencer.cc
@@ -360,20 +360,22 @@ Sequencer::writeCallback(Addr address, DataBlock& data,
             } else {
                 aliased_stores++;
             }
+            markRemoved();
+            ruby_request = false;
             hitCallback(&seq_req, data, success, mach, externalHit,
                         initialRequestTime, forwardRequestTime,
                         firstResponseTime);
         } else {
             // handle read request
             assert(!ruby_request);
+            markRemoved();
+            ruby_request = false;
             aliased_loads++;
             hitCallback(&seq_req, data, true, mach, externalHit,
                         initialRequestTime, forwardRequestTime,
                         firstResponseTime);
         }
         seq_req_list.pop_front();
-        markRemoved();
-        ruby_request = false;
     }
 
     // free all outstanding requests corresponding to this address
@@ -421,12 +423,12 @@ Sequencer::readCallback(Addr address, DataBlock& data,
                               initialRequestTime, forwardRequestTime,
                               firstResponseTime);
         }
+        markRemoved();
+        ruby_request = false;
         hitCallback(&seq_req, data, true, mach, externalHit,
                     initialRequestTime, forwardRequestTime,
                     firstResponseTime);
         seq_req_list.pop_front();
-        markRemoved();
-        ruby_request = false;
     }
 
     // free all outstanding requests corresponding to this address
-- 
2.30.2