mac80211: introduce aql_enable node in debugfs

Introduce aql_enable node in debugfs in order to enable/disable aql.
This is useful for debugging purpose.
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/e7a934d5d84e4796c4f97ea5de4e66c824296b07.1610214851.git.lorenzo@kernel.orgSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/debugfs.c

@@ -281,6 +281,56 @@ static const struct file_operations aql_txq_limit_ops = {
 	.llseek = default_llseek,
 };
 
+static ssize_t aql_enable_read(struct file *file, char __user *user_buf,
+			       size_t count, loff_t *ppos)
+{
+	char buf[3];
+	int len;
+
+	len = scnprintf(buf, sizeof(buf), "%d\n",
+			!static_key_false(&aql_disable.key));
+
+	return simple_read_from_buffer(user_buf, count, ppos, buf, len);
+}
+
+static ssize_t aql_enable_write(struct file *file, const char __user *user_buf,
+				size_t count, loff_t *ppos)
+{
+	bool aql_disabled = static_key_false(&aql_disable.key);
+	char buf[3];
+	size_t len;
+
+	if (count > sizeof(buf))
+		return -EINVAL;
+
+	if (copy_from_user(buf, user_buf, count))
+		return -EFAULT;
+
+	buf[sizeof(buf) - 1] = '\0';
+	len = strlen(buf);
+	if (len > 0 && buf[len - 1] == '\n')
+		buf[len - 1] = 0;
+
+	if (buf[0] == '0' && buf[1] == '\0') {
+		if (!aql_disabled)
+			static_branch_inc(&aql_disable);
+	} else if (buf[0] == '1' && buf[1] == '\0') {
+		if (aql_disabled)
+			static_branch_dec(&aql_disable);
+	} else {
+		return -EINVAL;
+	}
+
+	return count;
+}
+
+static const struct file_operations aql_enable_ops = {
+	.write = aql_enable_write,
+	.read = aql_enable_read,
+	.open = simple_open,
+	.llseek = default_llseek,
+};
+
 static ssize_t force_tx_status_read(struct file *file,
 				    char __user *user_buf,
 				    size_t count,
@@ -569,6 +619,7 @@ void debugfs_hw_add(struct ieee80211_local *local)
 	DEBUGFS_ADD(power);
 	DEBUGFS_ADD(hw_conf);
 	DEBUGFS_ADD_MODE(force_tx_status, 0600);
+	DEBUGFS_ADD_MODE(aql_enable, 0600);
 
 	if (local->ops->wake_tx_queue)
 		DEBUGFS_ADD_MODE(aqm, 0600);

net/mac80211/ieee80211_i.h

@@ -1142,6 +1142,8 @@ enum mac80211_scan_state {
 	SCAN_ABORT,
 };
 
+DECLARE_STATIC_KEY_FALSE(aql_disable);
+
 struct ieee80211_local {
 	/* embed the driver visible part.
 	 * don't cast (use the static inlines below), but we keep

net/mac80211/tx.c

@@ -3811,6 +3811,8 @@ void __ieee80211_schedule_txq(struct ieee80211_hw *hw,
 }
 EXPORT_SYMBOL(__ieee80211_schedule_txq);
 
+DEFINE_STATIC_KEY_FALSE(aql_disable);
+
 bool ieee80211_txq_airtime_check(struct ieee80211_hw *hw,
 				 struct ieee80211_txq *txq)
 {
@@ -3820,6 +3822,9 @@ bool ieee80211_txq_airtime_check(struct ieee80211_hw *hw,
 	if (!wiphy_ext_feature_isset(local->hw.wiphy, NL80211_EXT_FEATURE_AQL))
 		return true;
 
+	if (static_branch_unlikely(&aql_disable))
+		return true;
+
 	if (!txq->sta)
 		return true;