Revert "mem-cache: Remove writebacks packet list"

This reverts commit bf0a722acdd8247602e83720a5f81a0b69c76250.

Reason for revert: This patch introduces a bug:

The problem here is that the insertion of block A may cause the
eviction of block B, which on the lower level may cause the
eviction of block A. Since A is not marked as present yet, A is
"safely" removed from the snoop filter

However, by reverting it, using atomic and a Tags sub-class that
can generate multiple evictions at once becomes broken when using
Atomic mode and shall be fixed in a future patch.

Change-Id: I5b27e54b54ae5b50255588835c1a2ebf3015f002
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/19088
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/src/mem/cache/cache.hh b/src/mem/cache/cache.hh
index d1b876e6d..33c5a2412 100644
--- a/src/mem/cache/cache.hh
+++ b/src/mem/cache/cache.hh
@@ -87,7 +87,8 @@ class Cache : public BaseCache
      */
     void promoteWholeLineWrites(PacketPtr pkt);
 
-    bool access(PacketPtr pkt, CacheBlk *&blk, Cycles &lat) override;
+    bool access(PacketPtr pkt, CacheBlk *&blk, Cycles &lat,
+                PacketList &writebacks) override;
 
     void handleTimingReqHit(PacketPtr pkt, CacheBlk *blk,
                             Tick request_time) override;
@@ -98,9 +99,9 @@ class Cache : public BaseCache
 
     void recvTimingReq(PacketPtr pkt) override;
 
-    void doWritebacks(PacketPtr pkt, Tick forward_time) override;
+    void doWritebacks(PacketList& writebacks, Tick forward_time) override;
 
-    void doWritebacksAtomic(PacketPtr pkt) override;
+    void doWritebacksAtomic(PacketList& writebacks) override;
 
     void serviceMSHRTargets(MSHR *mshr, const PacketPtr pkt,
                             CacheBlk *blk) override;
@@ -109,7 +110,8 @@ class Cache : public BaseCache
 
     void recvTimingSnoopResp(PacketPtr pkt) override;
 
-    Cycles handleAtomicReqMiss(PacketPtr pkt, CacheBlk *&blk) override;
+    Cycles handleAtomicReqMiss(PacketPtr pkt, CacheBlk *&blk,
+                               PacketList &writebacks) override;
 
     Tick recvAtomic(PacketPtr pkt) override;