From 0e89a6b8bd5ffb02f6e364e34678628de79ab378 Mon Sep 17 00:00:00 2001
From: acfloria <florian.achermann@mavt.ethz.ch>
Date: Tue, 13 Mar 2018 15:05:35 +0100
Subject: [PATCH] IridiumSBD: Do not allow stopping the driver when the device
 is used to prevent hardfault

---
 .../telemetry/iridiumsbd/IridiumSBD.cpp       | 19 +++++++++++++
 src/drivers/telemetry/iridiumsbd/IridiumSBD.h | 28 +++++++++++++++++++
 2 files changed, 47 insertions(+)

diff --git a/src/drivers/telemetry/iridiumsbd/IridiumSBD.cpp b/src/drivers/telemetry/iridiumsbd/IridiumSBD.cpp
index 665d1ad09b..01e9eee837 100644
--- a/src/drivers/telemetry/iridiumsbd/IridiumSBD.cpp
+++ b/src/drivers/telemetry/iridiumsbd/IridiumSBD.cpp
@@ -91,6 +91,11 @@ int IridiumSBD::stop()
 		return PX4_ERROR;
 	}
 
+	if (IridiumSBD::instance->cdev_used) {
+		PX4_WARN("device is used. Stop all users (MavLink)");
+		return PX4_ERROR;
+	}
+
 	PX4_WARN("stopping...");
 
 	IridiumSBD::instance->task_should_exit = true;
@@ -922,6 +927,20 @@ void IridiumSBD::publish_telemetry_status()
 	}
 }
 
+int	IridiumSBD::open_first(struct file *filep)
+{
+	cdev_used = true;
+	return CDev::open_first(filep);
+}
+
+int	IridiumSBD::close_last(struct file *filep)
+{
+	cdev_used = false;
+	return CDev::close_last(filep);
+}
+
+
+
 int iridiumsbd_main(int argc, char *argv[])
 {
 	if (!strcmp(argv[1], "start")) {
diff --git a/src/drivers/telemetry/iridiumsbd/IridiumSBD.h b/src/drivers/telemetry/iridiumsbd/IridiumSBD.h
index 2d7acc96f5..2deaa6441c 100644
--- a/src/drivers/telemetry/iridiumsbd/IridiumSBD.h
+++ b/src/drivers/telemetry/iridiumsbd/IridiumSBD.h
@@ -261,6 +261,32 @@ private:
 	 */
 	void publish_telemetry_status(void);
 
+	/**
+	 * Notification of the first open of CDev.
+	 *
+	 * This function is called when the device open count transitions from zero
+	 * to one.  The driver lock is held for the duration of the call.
+	 *
+	 * Notes that CDev is used and blocks stopping the driver.
+	 *
+	 * @param filep		Pointer to the NuttX file structure.
+	 * @return		OK if the open should proceed, -errno otherwise.
+	 */
+	virtual int	open_first(struct file *filep) override;
+
+	/**
+	 * Notification of the last close of CDev.
+	 *
+	 * This function is called when the device open count transitions from
+	 * one to zero.  The driver lock is held for the duration of the call.
+	 *
+	 * Notes that CDev is not used anymore and allows stopping the driver.
+	 *
+	 * @param filep		Pointer to the NuttX file structure.
+	 * @return		OK if the open should return OK, -errno otherwise.
+	 */
+	virtual int	close_last(struct file *filep) override;
+
 	static IridiumSBD *instance;
 	static int task_handle;
 	bool task_should_exit = false;
@@ -295,6 +321,8 @@ private:
 	bool rx_read_pending = false;
 	bool tx_session_pending = false;
 
+	bool cdev_used = false;
+
 	hrt_abstime last_write_time = 0;
 	hrt_abstime last_read_time = 0;
 	hrt_abstime last_heartbeat = 0;