cfg80211: regulatory: introduce NL80211_RRF_AUTO_BW rule flag

Introduce NL80211_RRF_AUTO_BW rule flag. If this flag set
maximum available bandwidth should be calculated base on
contiguous rules and wider channels will be allowed to cross
multiple contiguous/overlapping frequency ranges.

In case of old kernels maximum bandwidth from regulatory
rule will be used, while there is no NL80211_RRF_AUTO_BW flag.

This fixes the previous commit 9752482083066af7ac18a5ca376f
("cfg80211: regulatory introduce maximum bandwidth calculation")
which was found to be a problem for userspace API compatibility.

Signed-off-by: Janusz Dziedzic <janusz.dziedzic@tieto.com>
[edit commit log, use sizeof()]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/uapi/linux/nl80211.h

@@ -2443,10 +2443,7 @@ enum nl80211_reg_type {
  * 	in KHz. This is not a center a frequency but an actual regulatory
  * 	band edge.
  * @NL80211_ATTR_FREQ_RANGE_MAX_BW: maximum allowed bandwidth for this
- *	frequency range, in KHz. If not present or 0, maximum available
- *	bandwidth should be calculated base on contiguous rules and wider
- *	channels will be allowed to cross multiple contiguous/overlapping
- *	frequency ranges.
+ *	frequency range, in KHz.
  * @NL80211_ATTR_POWER_RULE_MAX_ANT_GAIN: the maximum allowed antenna gain
  * 	for a given frequency range. The value is in mBi (100 * dBi).
  * 	If you don't have one then don't send this.
@@ -2517,6 +2514,9 @@ enum nl80211_sched_scan_match_attr {
  * @NL80211_RRF_NO_IR: no mechanisms that initiate radiation are allowed,
  * 	this includes probe requests or modes of operation that require
  * 	beaconing.
+ * @NL80211_RRF_AUTO_BW: maximum available bandwidth should be calculated
+ *	base on contiguous rules and wider channels will be allowed to cross
+ *	multiple contiguous/overlapping frequency ranges.
  */
 enum nl80211_reg_rule_flags {
 	NL80211_RRF_NO_OFDM		= 1<<0,
@@ -2528,6 +2528,7 @@ enum nl80211_reg_rule_flags {
 	NL80211_RRF_PTMP_ONLY		= 1<<6,
 	NL80211_RRF_NO_IR		= 1<<7,
 	__NL80211_RRF_NO_IBSS		= 1<<8,
+	NL80211_RRF_AUTO_BW		= 1<<11,
 };
 
 #define NL80211_RRF_PASSIVE_SCAN	NL80211_RRF_NO_IR

net/wireless/genregdb.awk

@@ -105,6 +105,8 @@ function parse_reg_rule()
 			flags = flags "\n\t\t\tNL80211_RRF_NO_IR | "
 		} else if (flagarray[arg] == "NO-IR") {
 			flags = flags "\n\t\t\tNL80211_RRF_NO_IR | "
+		} else if (flagarray[arg] == "AUTO-BW") {
+			flags = flags "\n\t\t\tNL80211_RRF_AUTO_BW | "
 		}
 
 	}

net/wireless/nl80211.c

@@ -4628,6 +4628,8 @@ static int parse_reg_rule(struct nlattr *tb[],
 		return -EINVAL;
 	if (!tb[NL80211_ATTR_FREQ_RANGE_END])
 		return -EINVAL;
+	if (!tb[NL80211_ATTR_FREQ_RANGE_MAX_BW])
+		return -EINVAL;
 	if (!tb[NL80211_ATTR_POWER_RULE_MAX_EIRP])
 		return -EINVAL;
 
@@ -4637,9 +4639,8 @@ static int parse_reg_rule(struct nlattr *tb[],
 		nla_get_u32(tb[NL80211_ATTR_FREQ_RANGE_START]);
 	freq_range->end_freq_khz =
 		nla_get_u32(tb[NL80211_ATTR_FREQ_RANGE_END]);
-	if (tb[NL80211_ATTR_FREQ_RANGE_MAX_BW])
-		freq_range->max_bandwidth_khz =
-			nla_get_u32(tb[NL80211_ATTR_FREQ_RANGE_MAX_BW]);
+	freq_range->max_bandwidth_khz =
+		nla_get_u32(tb[NL80211_ATTR_FREQ_RANGE_MAX_BW]);
 
 	power_rule->max_eirp =
 		nla_get_u32(tb[NL80211_ATTR_POWER_RULE_MAX_EIRP]);

net/wireless/reg.c

@@ -563,9 +563,6 @@ unsigned int reg_get_max_bandwidth(const struct ieee80211_regdomain *rd,
 		if (freq_range_tmp->end_freq_khz < freq_range->start_freq_khz)
 			break;
 
-		if (freq_range_tmp->max_bandwidth_khz)
-			break;
-
 		freq_range = freq_range_tmp;
 	}
 
@@ -582,9 +579,6 @@ unsigned int reg_get_max_bandwidth(const struct ieee80211_regdomain *rd,
 		if (freq_range_tmp->start_freq_khz > freq_range->end_freq_khz)
 			break;
 
-		if (freq_range_tmp->max_bandwidth_khz)
-			break;
-
 		freq_range = freq_range_tmp;
 	}
 
@@ -729,21 +723,29 @@ static int reg_rules_intersect(const struct ieee80211_regdomain *rd1,
 	max_bandwidth1 = freq_range1->max_bandwidth_khz;
 	max_bandwidth2 = freq_range2->max_bandwidth_khz;
 
-	/*
-	 * In case max_bandwidth1 == 0 and max_bandwith2 == 0 set
-	 * output bandwidth as 0 (auto calculation). Next we will
-	 * calculate this correctly in handle_channel function.
-	 * In other case calculate output bandwidth here.
-	 */
-	if (max_bandwidth1 || max_bandwidth2) {
-		if (!max_bandwidth1)
-			max_bandwidth1 = reg_get_max_bandwidth(rd1, rule1);
-		if (!max_bandwidth2)
-			max_bandwidth2 = reg_get_max_bandwidth(rd2, rule2);
-	}
+	if (rule1->flags & NL80211_RRF_AUTO_BW)
+		max_bandwidth1 = reg_get_max_bandwidth(rd1, rule1);
+	if (rule2->flags & NL80211_RRF_AUTO_BW)
+		max_bandwidth2 = reg_get_max_bandwidth(rd2, rule2);
 
 	freq_range->max_bandwidth_khz = min(max_bandwidth1, max_bandwidth2);
 
+	intersected_rule->flags = rule1->flags | rule2->flags;
+
+	/*
+	 * In case NL80211_RRF_AUTO_BW requested for both rules
+	 * set AUTO_BW in intersected rule also. Next we will
+	 * calculate BW correctly in handle_channel function.
+	 * In other case remove AUTO_BW flag while we calculate
+	 * maximum bandwidth correctly and auto calculation is
+	 * not required.
+	 */
+	if ((rule1->flags & NL80211_RRF_AUTO_BW) &&
+	    (rule2->flags & NL80211_RRF_AUTO_BW))
+		intersected_rule->flags |= NL80211_RRF_AUTO_BW;
+	else
+		intersected_rule->flags &= ~NL80211_RRF_AUTO_BW;
+
 	freq_diff = freq_range->end_freq_khz - freq_range->start_freq_khz;
 	if (freq_range->max_bandwidth_khz > freq_diff)
 		freq_range->max_bandwidth_khz = freq_diff;
@@ -753,8 +755,6 @@ static int reg_rules_intersect(const struct ieee80211_regdomain *rd1,
 	power_rule->max_antenna_gain = min(power_rule1->max_antenna_gain,
 		power_rule2->max_antenna_gain);
 
-	intersected_rule->flags = rule1->flags | rule2->flags;
-
 	if (!is_valid_reg_rule(intersected_rule))
 		return -EINVAL;
 
@@ -938,31 +938,42 @@ const char *reg_initiator_name(enum nl80211_reg_initiator initiator)
 EXPORT_SYMBOL(reg_initiator_name);
 
 #ifdef CONFIG_CFG80211_REG_DEBUG
-static void chan_reg_rule_print_dbg(struct ieee80211_channel *chan,
+static void chan_reg_rule_print_dbg(const struct ieee80211_regdomain *regd,
+				    struct ieee80211_channel *chan,
 				    const struct ieee80211_reg_rule *reg_rule)
 {
 	const struct ieee80211_power_rule *power_rule;
 	const struct ieee80211_freq_range *freq_range;
-	char max_antenna_gain[32];
+	char max_antenna_gain[32], bw[32];
 
 	power_rule = &reg_rule->power_rule;
 	freq_range = &reg_rule->freq_range;
 
 	if (!power_rule->max_antenna_gain)
-		snprintf(max_antenna_gain, 32, "N/A");
+		snprintf(max_antenna_gain, sizeof(max_antenna_gain), "N/A");
 	else
-		snprintf(max_antenna_gain, 32, "%d", power_rule->max_antenna_gain);
+		snprintf(max_antenna_gain, sizeof(max_antenna_gain), "%d",
+			 power_rule->max_antenna_gain);
+
+	if (reg_rule->flags & NL80211_RRF_AUTO_BW)
+		snprintf(bw, sizeof(bw), "%d KHz, %d KHz AUTO",
+			 freq_range->max_bandwidth_khz,
+			 reg_get_max_bandwidth(regd, reg_rule));
+	else
+		snprintf(bw, sizeof(bw), "%d KHz",
+			 freq_range->max_bandwidth_khz);
 
 	REG_DBG_PRINT("Updating information on frequency %d MHz with regulatory rule:\n",
 		      chan->center_freq);
 
-	REG_DBG_PRINT("%d KHz - %d KHz @ %d KHz), (%s mBi, %d mBm)\n",
+	REG_DBG_PRINT("%d KHz - %d KHz @ %s), (%s mBi, %d mBm)\n",
 		      freq_range->start_freq_khz, freq_range->end_freq_khz,
-		      freq_range->max_bandwidth_khz, max_antenna_gain,
+		      bw, max_antenna_gain,
 		      power_rule->max_eirp);
 }
 #else
-static void chan_reg_rule_print_dbg(struct ieee80211_channel *chan,
+static void chan_reg_rule_print_dbg(const struct ieee80211_regdomain *regd,
+				    struct ieee80211_channel *chan,
 				    const struct ieee80211_reg_rule *reg_rule)
 {
 	return;
@@ -1022,17 +1033,16 @@ static void handle_channel(struct wiphy *wiphy,
 		return;
 	}
 
-	chan_reg_rule_print_dbg(chan, reg_rule);
+	regd = reg_get_regdomain(wiphy);
+	chan_reg_rule_print_dbg(regd, chan, reg_rule);
 
 	power_rule = &reg_rule->power_rule;
 	freq_range = &reg_rule->freq_range;
 
 	max_bandwidth_khz = freq_range->max_bandwidth_khz;
 	/* Check if auto calculation requested */
-	if (!max_bandwidth_khz) {
-		regd = reg_get_regdomain(wiphy);
+	if (reg_rule->flags & NL80211_RRF_AUTO_BW)
 		max_bandwidth_khz = reg_get_max_bandwidth(regd, reg_rule);
-	}
 
 	if (max_bandwidth_khz < MHZ_TO_KHZ(40))
 		bw_flags = IEEE80211_CHAN_NO_HT40;
@@ -1437,14 +1447,14 @@ static void handle_channel_custom(struct wiphy *wiphy,
 		return;
 	}
 
-	chan_reg_rule_print_dbg(chan, reg_rule);
+	chan_reg_rule_print_dbg(regd, chan, reg_rule);
 
 	power_rule = &reg_rule->power_rule;
 	freq_range = &reg_rule->freq_range;
 
 	max_bandwidth_khz = freq_range->max_bandwidth_khz;
 	/* Check if auto calculation requested */
-	if (!max_bandwidth_khz)
+	if (reg_rule->flags & NL80211_RRF_AUTO_BW)
 		max_bandwidth_khz = reg_get_max_bandwidth(regd, reg_rule);
 
 	if (max_bandwidth_khz < MHZ_TO_KHZ(40))
@@ -2254,11 +2264,12 @@ static void print_rd_rules(const struct ieee80211_regdomain *rd)
 		freq_range = &reg_rule->freq_range;
 		power_rule = &reg_rule->power_rule;
 
-		if (!freq_range->max_bandwidth_khz)
-			snprintf(bw, 32, "%d KHz, AUTO",
+		if (reg_rule->flags & NL80211_RRF_AUTO_BW)
+			snprintf(bw, sizeof(bw), "%d KHz, %d KHz AUTO",
+				 freq_range->max_bandwidth_khz,
 				 reg_get_max_bandwidth(rd, reg_rule));
 		else
-			snprintf(bw, 32, "%d KHz",
+			snprintf(bw, sizeof(bw), "%d KHz",
 				 freq_range->max_bandwidth_khz);
 
 		/*