fix for bug #526.

Insert pseudo packet under low load conditions to complete rule swap.
This is necessary when we use autofp active packets where most packets
would be sent to the first queue under low load conditions.

src/detect-engine.c

@@ -449,6 +449,7 @@ static void *DetectEngineLiveRuleSwap(void *arg)
 
     DetectEngineThreadCtx *old_det_ctx[no_of_detect_tvs];
     DetectEngineThreadCtx *new_det_ctx[no_of_detect_tvs];
+    ThreadVars *detect_tvs[no_of_detect_tvs];
 
     /* all receive threads are part of packet processing threads */
     tv = tv_root[TVT_PPT];
@@ -465,6 +466,7 @@ static void *DetectEngineLiveRuleSwap(void *arg)
             }
 
             old_det_ctx[i] = SC_ATOMIC_GET(slots->slot_data);
+            detect_tvs[i] = tv;
 
             DetectEngineThreadCtx *det_ctx = NULL;
             DetectEngineThreadCtxInitForLiveRuleSwap(tv, (void *)de_ctx,
@@ -492,12 +494,28 @@ static void *DetectEngineLiveRuleSwap(void *arg)
 
     for (i = 0; i < no_of_detect_tvs; i++) {
         int break_out = 0;
+        int pseudo_pkt_inserted = 0;
+        usleep(1000);
         while (SC_ATOMIC_GET(new_det_ctx[i]->so_far_used_by_detect) != 1) {
             if (suricata_ctl_flags != 0) {
                 break_out = 1;
                 break;
             }
 
+            if (pseudo_pkt_inserted == 0) {
+                pseudo_pkt_inserted = 1;
+                if (detect_tvs[i]->inq != NULL) {
+                    Packet *p = PacketGetFromAlloc();
+                    if (p != NULL) {
+                        PacketQueue *q = &trans_q[detect_tvs[i]->inq->id];
+                        SCMutexLock(&q->mutex_q);
+
+                        PacketEnqueue(q, p);
+                        SCCondSignal(&q->cond_q);
+                        SCMutexUnlock(&q->mutex_q);
+                    }
+                }
+            }
             usleep(1000);
         }
         if (break_out)