flow engine: no longer allow FlowRequeue to be called with the same src and dst queue.

src/flow-queue.c

@@ -136,18 +136,17 @@ Flow *FlowDequeue (FlowQueue *q) {
  *  \brief Transfer a flow from one queue to another
  *
  *  \param f the flow to be transfered
- *  \param srcq the source queue, where the flow will be removed. The param may
- *              be NULL.
+ *  \param srcq the source queue, where the flow will be removed.
  *  \param dstq the dest queue where the flow will be placed
  *
+ *  \note srcq and dstq must be different queues.
  */
 void FlowRequeue(Flow *f, FlowQueue *srcq, FlowQueue *dstq)
 {
 #ifdef DEBUG
-    BUG_ON(dstq == NULL);
+    BUG_ON(srcq == NULL || dstq == NULL || srcq == dstq);
 #endif /* DEBUG */
 
-    if (srcq != NULL) {
     SCMutexLock(&srcq->mutex_q);
 
     /* remove from old queue */
@@ -169,16 +168,9 @@ void FlowRequeue(Flow *f, FlowQueue *srcq, FlowQueue *dstq)
     f->lnext = NULL;
     f->lprev = NULL;
 
-        /* don't unlock if src and dst are the same */
-        if (srcq != dstq) {
     SCMutexUnlock(&srcq->mutex_q);
-        }
-    }
 
-    /* now put it in dst */
-    if (srcq != dstq) {
     SCMutexLock(&dstq->mutex_q);
-    }
 
     /* add to new queue (append) */
     f->lprev = dstq->bot;