defrag: clean up existing stats counters

7a044a9 removed the lines that incremented these defrag
counters, but kept the entities themselves. This commit removes counters
that we judge too complex to maintain, given the current state of the
code, and re-adds incrementing max_hit (memcap related).

Related to
Task OISF#5816

src/decode.c

@@ -587,16 +587,10 @@ void DecodeRegisterPerfCounters(DecodeThreadVars *dtv, ThreadVars *tv)
 
     dtv->counter_defrag_ipv4_fragments =
         StatsRegisterCounter("defrag.ipv4.fragments", tv);
-    dtv->counter_defrag_ipv4_reassembled =
-        StatsRegisterCounter("defrag.ipv4.reassembled", tv);
-    dtv->counter_defrag_ipv4_timeouts =
-        StatsRegisterCounter("defrag.ipv4.timeouts", tv);
+    dtv->counter_defrag_ipv4_reassembled = StatsRegisterCounter("defrag.ipv4.reassembled", tv);
     dtv->counter_defrag_ipv6_fragments =
         StatsRegisterCounter("defrag.ipv6.fragments", tv);
-    dtv->counter_defrag_ipv6_reassembled =
-        StatsRegisterCounter("defrag.ipv6.reassembled", tv);
-    dtv->counter_defrag_ipv6_timeouts =
-        StatsRegisterCounter("defrag.ipv6.timeouts", tv);
+    dtv->counter_defrag_ipv6_reassembled = StatsRegisterCounter("defrag.ipv6.reassembled", tv);
     dtv->counter_defrag_max_hit =
         StatsRegisterCounter("defrag.max_frag_hits", tv);
 

src/decode.h

@@ -710,10 +710,8 @@ typedef struct DecodeThreadVars_
     /** frag stats - defrag runs in the context of the decoder. */
     uint16_t counter_defrag_ipv4_fragments;
     uint16_t counter_defrag_ipv4_reassembled;
-    uint16_t counter_defrag_ipv4_timeouts;
     uint16_t counter_defrag_ipv6_fragments;
     uint16_t counter_defrag_ipv6_reassembled;
-    uint16_t counter_defrag_ipv6_timeouts;
     uint16_t counter_defrag_max_hit;
 
     uint16_t counter_flow_memcap;

src/defrag.c

@@ -1041,8 +1041,10 @@ Defrag(ThreadVars *tv, DecodeThreadVars *dtv, Packet *p)
 
     /* return a locked tracker or NULL */
     tracker = DefragGetTracker(tv, dtv, p);
-    if (tracker == NULL)
+    if (tracker == NULL) {
+        StatsIncr(tv, dtv->counter_defrag_max_hit);
         return NULL;
+    }
 
     Packet *rp = DefragInsertFrag(tv, dtv, tracker, p);
     DefragTrackerRelease(tracker);