MT#55283 protect against possibly signed int

and add an additional comment

Change-Id: I5cb3f434a21879343568f87425356507c2717d7b

kernel-module/nft_rtpengine.c

@@ -4240,7 +4240,7 @@ static struct re_timer_thread *launch_thread(unsigned int cpu) {
 static int init_play_streams(unsigned int n_play_streams, unsigned int n_stream_packets) {
 	int ret = 0;
 	struct re_timer_thread **threads_new = NULL;
-	unsigned int new_num_threads = 0;
+	int new_num_threads = 0;
 	bool need_threads;
 	struct re_play_stream **new_play_streams, **old_play_streams = NULL;
 	struct re_play_stream_packets **new_stream_packets, **old_stream_packets = NULL;
@@ -4270,7 +4270,7 @@ static int init_play_streams(unsigned int n_play_streams, unsigned int n_stream_
 	if (need_threads) {
 		ret = -ENXIO;
 		new_num_threads = num_online_cpus();
-		if (new_num_threads == 0)
+		if (new_num_threads <= 0)
 			goto err;
 
 		threads_new = kzalloc(sizeof(*threads_new) * new_num_threads, GFP_KERNEL);

kernel-module/nft_rtpengine.h

@@ -121,8 +121,8 @@ struct rtpengine_target_info {
 		size_t				len;
 	}				mid_output[RTPE_NUM_OUTPUT_MEDIA];
 
-	struct interface_stats_block	*iface_stats; // for ingress stats
-	struct stream_stats		*stats; // for ingress stats
+	struct interface_stats_block	*iface_stats; // for ingress stats, pinned memory
+	struct stream_stats		*stats; // for ingress stats, pinned memory
 
 	unsigned int			extmap:1,
 					dtls:1,