flow: simplify hash lookup logic

Remove double compare paths in favor of a single unified path.

src/flow-hash.c

@@ -634,49 +634,17 @@ Flow *FlowGetFlowFromHash(ThreadVars *tv, DecodeThreadVars *dtv, const Packet *p
     }
 
     /* ok, we have a flow in the bucket. Let's find out if it is our flow */
-    f = fb->head;
-
-    /* see if this is the flow we are looking for */
-    if (FlowCompare(f, p) == 0) {
     Flow *pf = NULL; /* previous flow */
-
+    f = fb->head;
-        while (f) {
+    do {
-            pf = f;
-            f = f->hnext;
-
-            if (f == NULL) {
-                f = pf->hnext = FlowGetNew(tv, dtv, p);
-                if (f == NULL) {
-                    FBLOCK_UNLOCK(fb);
-                    return NULL;
-                }
-                fb->tail = f;
-
-                /* flow is locked */
-
-                f->hprev = pf;
-
-                /* initialize and return */
-                FlowInit(f, p);
-                f->flow_hash = hash;
-                f->fb = fb;
-                FlowUpdateState(f, FLOW_STATE_NEW);
-
-                FlowReference(dest, f);
-
-                FBLOCK_UNLOCK(fb);
-                return f;
-            }
-
         if (FlowCompare(f, p) != 0) {
             /* we found our flow, lets put it on top of the
              * hash list -- this rewards active flows */
+            if (f->hprev) {
                 if (f->hnext) {
                     f->hnext->hprev = f->hprev;
                 }
-                if (f->hprev) {
                 f->hprev->hnext = f->hnext;
-                }
                 if (f == fb->tail) {
                     fb->tail = f->hprev;
                 }
@@ -685,7 +653,7 @@ Flow *FlowGetFlowFromHash(ThreadVars *tv, DecodeThreadVars *dtv, const Packet *p
                 f->hprev = NULL;
                 fb->head->hprev = f;
                 fb->head = f;
-
+            }
             /* found our flow, lock & return */
             FLOWLOCK_WRLOCK(f);
             if (unlikely(TcpSessionPacketSsnReuse(p, f, f->protoctx) == 1)) {
@@ -701,23 +669,35 @@ Flow *FlowGetFlowFromHash(ThreadVars *tv, DecodeThreadVars *dtv, const Packet *p
             FBLOCK_UNLOCK(fb);
             return f;
         }
-        }
+        if (f->hnext == NULL) {
-    }
+            pf = f;
-
+            f = pf->hnext = FlowGetNew(tv, dtv, p);
-    /* lock & return */
-    FLOWLOCK_WRLOCK(f);
-    if (unlikely(TcpSessionPacketSsnReuse(p, f, f->protoctx) == 1)) {
-        f = TcpReuseReplace(tv, dtv, fb, f, hash, p);
             if (f == NULL) {
                 FBLOCK_UNLOCK(fb);
                 return NULL;
             }
-    }
+            fb->tail = f;
 
-    FlowReference(dest, f);
+            /* flow is locked */
+
+            f->hprev = pf;
 
+            /* initialize and return */
+            FlowInit(f, p);
+            f->flow_hash = hash;
+            f->fb = fb;
+            FlowUpdateState(f, FLOW_STATE_NEW);
+            FlowReference(dest, f);
             FBLOCK_UNLOCK(fb);
             return f;
+        }
+        pf = f;
+        f = f->hnext;
+    } while (f != NULL);
+
+    /* should be unreachable */
+    BUG_ON(1);
+    return NULL;
 }
 
 static inline int FlowCompareKey(Flow *f, FlowKey *key)