From ac1368df50af123b32b41d7115ea4a0f15f7c97f Mon Sep 17 00:00:00 2001
From: Andreas Hansson <andreas.hansson@arm.com>
Date: Fri, 6 Nov 2015 03:26:21 -0500
Subject: mem: Unify delayed packet deletion

This patch unifies how we deal with delayed packet deletion, where the
receiving slave is responsible for deleting the packet, but the
sending agent (e.g. a cache) is still relying on the pointer until the
call to sendTimingReq completes. Previously we used a mix of a
deletion vector and a construct using unique_ptr. With this patch we
ensure all slaves use the latter approach.
---
 src/mem/cache/cache.cc | 29 +++++++++--------------------
 src/mem/cache/cache.hh |  7 +++----
 2 files changed, 12 insertions(+), 24 deletions(-)

(limited to 'src/mem/cache')

diff --git a/src/mem/cache/cache.cc b/src/mem/cache/cache.cc
index 3e5ed42bc..aa95d5604 100644
--- a/src/mem/cache/cache.cc
+++ b/src/mem/cache/cache.cc
@@ -542,15 +542,6 @@ bool
 Cache::recvTimingReq(PacketPtr pkt)
 {
     DPRINTF(CacheTags, "%s tags: %s\n", __func__, tags->print());
-//@todo Add back in MemDebug Calls
-//    MemDebug::cacheAccess(pkt);
-
-
-    /// @todo temporary hack to deal with memory corruption issue until
-    /// 4-phase transactions are complete
-    for (int x = 0; x < pendingDelete.size(); x++)
-        delete pendingDelete[x];
-    pendingDelete.clear();
 
     assert(pkt->isRequest());
 
@@ -602,10 +593,9 @@ Cache::recvTimingReq(PacketPtr pkt)
             // main memory will delete the packet
         }
 
-        /// @todo nominally we should just delete the packet here,
-        /// however, until 4-phase stuff we can't because sending
-        /// cache is still relying on it.
-        pendingDelete.push_back(pkt);
+        // queue for deletion, as the sending cache is still relying
+        // on the packet
+        pendingDelete.reset(pkt);
 
         // no need to take any action in this particular cache as the
         // caches along the path to memory are allowed to keep lines
@@ -678,12 +668,11 @@ Cache::recvTimingReq(PacketPtr pkt)
             // by access(), that calls accessBlock() function.
             cpuSidePort->schedTimingResp(pkt, request_time);
         } else {
-            /// @todo nominally we should just delete the packet here,
-            /// however, until 4-phase stuff we can't because sending cache is
-            /// still relying on it. If the block is found in access(),
-            /// CleanEvict and Writeback messages will be deleted here as
-            /// well.
-            pendingDelete.push_back(pkt);
+            // queue the packet for deletion, as the sending cache is
+            // still relying on it; if the block is found in access(),
+            // CleanEvict and Writeback messages will be deleted
+            // here as well
+            pendingDelete.reset(pkt);
         }
     } else {
         // miss
@@ -754,7 +743,7 @@ Cache::recvTimingReq(PacketPtr pkt)
                 // CleanEvicts corresponding to blocks which have outstanding
                 // requests in MSHRs can be deleted here.
                 if (pkt->cmd == MemCmd::CleanEvict) {
-                    pendingDelete.push_back(pkt);
+                    pendingDelete.reset(pkt);
                 } else {
                     DPRINTF(Cache, "%s coalescing MSHR for %s addr %#llx size %d\n",
                             __func__, pkt->cmdString(), pkt->getAddr(),
diff --git a/src/mem/cache/cache.hh b/src/mem/cache/cache.hh
index ec436201b..ae9e7e694 100644
--- a/src/mem/cache/cache.hh
+++ b/src/mem/cache/cache.hh
@@ -195,11 +195,10 @@ class Cache : public BaseCache
     const bool prefetchOnAccess;
 
     /**
-     * @todo this is a temporary workaround until the 4-phase code is committed.
-     * upstream caches need this packet until true is returned, so hold it for
-     * deletion until a subsequent call
+     * Upstream caches need this packet until true is returned, so
+     * hold it for deletion until a subsequent call
      */
-    std::vector<PacketPtr> pendingDelete;
+    std::unique_ptr<Packet> pendingDelete;
 
     /**
      * Does all the processing necessary to perform the provided request.
-- 
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