ath10k: add sanity checks for monitor management

Add a few checks and warnings to make it easier to
track any kind of monitor vdev mismanagement.
Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

drivers/net/wireless/ath/ath10k/mac.c

@@ -516,6 +516,11 @@ static int ath10k_monitor_start(struct ath10k *ar, int vdev_id)
 
 	lockdep_assert_held(&ar->conf_mutex);
 
+	if (!ar->monitor_present) {
+		ath10k_warn("mac montor stop -- monitor is not present\n");
+		return -EINVAL;
+	}
+
 	arg.vdev_id = vdev_id;
 	arg.channel.freq = channel->center_freq;
 	arg.channel.band_center_freq1 = ar->hw->conf.chandef.center_freq1;
@@ -566,6 +571,16 @@ static int ath10k_monitor_stop(struct ath10k *ar)
 
 	lockdep_assert_held(&ar->conf_mutex);
 
+	if (!ar->monitor_present) {
+		ath10k_warn("mac montor stop -- monitor is not present\n");
+		return -EINVAL;
+	}
+
+	if (!ar->monitor_enabled) {
+		ath10k_warn("mac montor stop -- monitor is not enabled\n");
+		return -EINVAL;
+	}
+
 	ret = ath10k_wmi_vdev_down(ar, ar->monitor_vdev_id);
 	if (ret)
 		ath10k_warn("Monitor vdev down failed: %d\n", ret);