acs - channels with same performance

choose random channel from channels
with same/best performance.

Signed-off-by: Janusz Dziedzic <janusz.dziedzic@iopsys.eu>

src/cntlr_acs.c

@@ -38,11 +38,15 @@
 
 int cntlr_acs_radio_channel_recalc(struct netif_radio *radio, struct acs_params *params)
 {
+	struct acs_params acs_params[64] = {};
+	int acs_params_num = 0;
 	struct opclass_entry *entry;
 	struct opclass *opclass;
 	int chan, pref, reas;
 	int pref_best = 0;
-	int i, j;
+	int pref_cur = 0;
+	int prefered[64] = {0};
+	int i, j, r;
 
 	opclass = &radio->opclass;
 
@@ -84,23 +88,69 @@ int cntlr_acs_radio_channel_recalc(struct netif_radio *radio, struct acs_params
 			if (params->skip_dfs_not_available && reas != CHANNEL_PREF_REASON_DFS_AVAILABLE)
 				continue;
 
-			/* Finally we are here, choose best value */
-			if (pref > pref_best) {
+			if (WARN_ON(acs_params_num >= ARRAY_SIZE(acs_params)))
+				break;
+
+			/* Current channel preference */
+			if (chan == params->best_channel)
+				pref_cur = pref;
+
+			/* Kick best value */
+			if (pref > pref_best)
 				pref_best = pref;
 
-				params->best_channel = chan;
-				params->best_opclass = entry->opclass;
-				params->best_bw = entry->bw;
-			}
+			acs_params[acs_params_num].best_channel = chan;
+			acs_params[acs_params_num].best_opclass = entry->opclass;
+			acs_params[acs_params_num].best_bw = entry->bw;
+			acs_params[acs_params_num].best_pref = pref;
+
+			acs_params_num++;
 		}
 	}
 
-	dbg("acs radio " MACFMT " best chan %d/%d opclass %d\n", MAC2STR(radio->macaddr),
-	    params->best_channel, params->best_bw, params->best_opclass);
-
 	if (!pref_best)
 		return -1;
 
+	dbg("acs radio " MACFMT " best pref %d vs current pref %d\n", MAC2STR(radio->macaddr), pref_best, pref_cur);
+
+	/* If current channel equal to best don't switch */
+	if (pref_cur == pref_best) {
+		dbg("acs skip - current channel %d is the best\n", params->best_channel);
+		return -1;
+	}
+
+	/* Get random channel from best performance */
+	for (i = 0, j = 0; i < acs_params_num; i++) {
+		if (acs_params[i].best_pref != pref_best)
+			continue;
+
+		if (j >= ARRAY_SIZE(prefered) - 1)
+			break;
+
+		/* Save index in table */
+		prefered[j] = i;
+		j++;
+	}
+
+	if (WARN_ON(!j))
+		return -1;
+
+	srand(time(NULL));
+	r = rand() % j;
+
+	dbg("acs radio " MACFMT " table size %d - rand %d, index %d\n",
+	    MAC2STR(radio->macaddr), j, r, prefered[r]);
+
+	if (prefered[r] >= acs_params_num)
+		return -1;
+
+	params->best_channel = acs_params[prefered[r]].best_channel;
+	params->best_bw = acs_params[prefered[r]].best_bw;
+	params->best_opclass = acs_params[prefered[r]].best_opclass;
+
+	dbg("acs radio " MACFMT " best chan %d/%d opclass %d\n", MAC2STR(radio->macaddr),
+	    params->best_channel, params->best_bw, params->best_opclass);
+
 	return 0;
 }
 
@@ -155,6 +205,7 @@ void cntlr_acs_node_channel_recalc(struct node *node, bool skip_dfs)
 
 		/* Use current opclass - TODO: if no opclass check 80/40/20 */
 		acs_params.opclass = cur_acs_params.opclass;
+		acs_params.best_channel = cur_acs_params.best_channel;
 
 		ret = cntlr_acs_radio_channel_recalc(radio, &acs_params);
 		if (WARN_ON(ret))

src/cntlr_acs.h

@@ -17,6 +17,7 @@ struct acs_params {
 	int best_channel;
 	int best_opclass;
 	int best_bw;
+	int best_pref;
 };
 
 int cntlr_acs_radio_channel_recalc(struct netif_radio *radio, struct acs_params *params);