mem: Fix bug in cache request retry mechanism

This patch ensures that inhibited packets that are about to be turned
into express snoops do not update the retry flag in the cache.

1 files changed, 7 insertions, 4 deletions

diff --git a/src/mem/cache/cache_impl.hh b/src/mem/cache/cache_impl.hh
index cb02f7558..62b65fc42 100644
--- a/src/mem/cache/cache_impl.hh
+++ b/src/mem/cache/cache_impl.hh
@@ -2029,11 +2029,14 @@ Cache<TagStore>::CpuSidePort::recvTimingReq(PacketPtr pkt)
 
     bool success = false;
 
-    // always let inhibited requests through, even if blocked
+    // always let inhibited requests through, even if blocked,
+    // ultimately we should check if this is an express snoop, but at
+    // the moment that flag is only set in the cache itself
     if (pkt->memInhibitAsserted()) {
-        // this should always succeed
-        success = cache->recvTimingReq(pkt);
-        assert(success);
+        // do not change the current retry state
+        bool M5_VAR_USED bypass_success = cache->recvTimingReq(pkt);
+        assert(bypass_success);
+        return true;
     } else if (blocked || mustSendRetry) {
         // either already committed to send a retry, or blocked
         success = false;