Fix an architectural issue with the ORB that prevented publication from interrupt context.

ORB topic advertisements are now global handles that can be used in any context.  It is still possible to open a topic node as a publisher, but it's not the default.  As a consequence, the type of the handle returned from orb_advertise has changed; all other API remains the same.

apps/attitude_estimator_ekf/attitude_estimator_ekf_main.c

@@ -138,7 +138,7 @@ int attitude_estimator_ekf_main(int argc, char *argv[])
 	/* subscribe to raw data */
 	int sub_raw = orb_subscribe(ORB_ID(sensor_combined));
 	/* advertise attitude */
-	int pub_att = orb_advertise(ORB_ID(vehicle_attitude), &att);
+	orb_advert_t pub_att = orb_advertise(ORB_ID(vehicle_attitude), &att);
 
 
 	int loopcounter = 0;

apps/commander/commander.c

@@ -96,7 +96,7 @@ static int buzzer;
 static int mavlink_fd;
 static bool commander_initialized = false;
 static struct vehicle_status_s current_status; /**< Main state machine */
-static int stat_pub;
+static orb_advert_t stat_pub;
 
 static uint16_t nofix_counter = 0;
 static uint16_t gotfix_counter = 0;

apps/drivers/drv_orb_dev.h

@@ -81,4 +81,7 @@
 /** Set the minimum interval at which the topic can be seen to be updated for this subscription */
 #define ORBIOCSETINTERVAL	_ORBIOC(12)
 
+/** Get the global advertiser handle for the topic */
+#define ORBIOCGADVERTISER	_ORBIOC(13)
+
 #endif /* _DRV_UORB_H */

apps/drivers/hmc5883/hmc5883.cpp

@@ -147,7 +147,7 @@ private:
 	mag_scale		_scale;
 	bool			_collect_phase;
 
-	int			_mag_topic;
+	orb_advert_t		_mag_topic;
 
 	unsigned		_reads;
 	unsigned		_measure_errors;

apps/drivers/mpu6000/mpu6000.cpp

@@ -181,12 +181,12 @@ private:
 	struct accel_report	_accel_report;
 	struct accel_scale	_accel_scale;
 	float			_accel_range_scale;
-	int			_accel_topic;
+	orb_advert_t		_accel_topic;
 
 	struct gyro_report	_gyro_report;
 	struct gyro_scale	_gyro_scale;
 	float			_gyro_range_scale;
-	int			_gyro_topic;
+	orb_advert_t		_gyro_topic;
 
 	unsigned		_reads;
 	perf_counter_t		_sample_perf;

apps/drivers/ms5611/ms5611.cpp

@@ -125,7 +125,7 @@ private:
 	int32_t			_dT;
 	int64_t			_temp64;
 
-	int			_baro_topic;
+	orb_advert_t		_baro_topic;
 
 	unsigned		_reads;
 	unsigned		_measure_errors;

apps/examples/px4_simple_app/px4_simple_app.c

@@ -59,7 +59,7 @@ int px4_simple_app_main(int argc, char *argv[])
 	/* advertise attitude topic */
 	struct vehicle_attitude_s att;
 	memset(&att, 0, sizeof(att));
-	int att_pub_fd = orb_advertise(ORB_ID(vehicle_attitude), &att);
+	orb_advert_t att_pub = orb_advertise(ORB_ID(vehicle_attitude), &att);
 
 	/* one could wait for multiple topics with this technique, just using one here */
 	struct pollfd fds[] = {
@@ -103,7 +103,7 @@ int px4_simple_app_main(int argc, char *argv[])
 				att.roll = raw.accelerometer_m_s2[0];
 				att.pitch = raw.accelerometer_m_s2[1];
 				att.yaw = raw.accelerometer_m_s2[2];
-				orb_publish(ORB_ID(vehicle_attitude), att_pub_fd, &att);
+				orb_publish(ORB_ID(vehicle_attitude), att_pub, &att);
 			}
 			/* there could be more file descriptors here, in the form like:
 			 * if (fds[1..n].revents & POLLIN) {}

apps/fixedwing_control/fixedwing_control.c

@@ -675,7 +675,7 @@ int fixedwing_control_main(int argc, char *argv[])
 
 	/* Set up to publish fixed wing control messages */
 	struct fixedwing_control_s control;
-	int fixedwing_control_pub = orb_advertise(ORB_ID(fixedwing_control), &control);
+	orb_advert_t fixedwing_control_pub = orb_advertise(ORB_ID(fixedwing_control), &control);
 
 	/* Subscribe to global position, attitude and rc */
 	struct vehicle_global_position_s global_pos;

apps/gps/mtk.c

@@ -311,7 +311,7 @@ void *mtk_loop(void *arg)
 	/* advertise GPS topic */
 	struct vehicle_gps_position_s mtk_gps_d;
 	mtk_gps = &mtk_gps_d;
-	int gps_handle = orb_advertise(ORB_ID(vehicle_gps_position), &mtk_gps);
+	orb_advert_t gps_handle = orb_advertise(ORB_ID(vehicle_gps_position), &mtk_gps);
 
 	while (1) {
 		/* Parse a message from the gps receiver */

apps/gps/nmea_helper.c

@@ -176,7 +176,7 @@ void *nmea_loop(void *arg)
 	/* advertise GPS topic */
 	struct vehicle_gps_position_s nmea_gps_d = {0};
 	nmea_gps = &nmea_gps_d;
-	int gps_handle = orb_advertise(ORB_ID(vehicle_gps_position), nmea_gps);
+	orb_advert_t gps_handle = orb_advertise(ORB_ID(vehicle_gps_position), nmea_gps);
 
 	while (1) {
 		/* Parse a message from the gps receiver */

apps/gps/ubx.c

@@ -842,7 +842,7 @@ void *ubx_loop(void *arg)
 
 	ubx_gps = &ubx_gps_d;
 
-	int gps_pub = orb_advertise(ORB_ID(vehicle_gps_position), &ubx_gps);
+	orb_advert_t gps_pub = orb_advertise(ORB_ID(vehicle_gps_position), &ubx_gps);
 
 	while (1) {
 		/* Parse a message from the gps receiver */

apps/mavlink/mavlink.c

@@ -113,7 +113,7 @@ static struct vehicle_status_s v_status;
 static struct rc_channels_s rc;
 
 /* HIL publishers */
-static int pub_hil_attitude = -1;
+static orb_advert_t pub_hil_attitude = -1;
 
 /** HIL attitude */
 static struct vehicle_attitude_s hil_attitude;
@@ -126,16 +126,16 @@ static struct ardrone_motors_setpoint_s ardrone_motors;
 
 static struct vehicle_command_s vcmd;
 
-static int pub_hil_global_pos = -1;
-static int ardrone_motors_pub = -1;
-static int cmd_pub = -1;
+static orb_advert_t pub_hil_global_pos = -1;
+static orb_advert_t ardrone_motors_pub = -1;
+static orb_advert_t cmd_pub = -1;
 static int sensor_sub = -1;
 static int att_sub = -1;
 static int global_pos_sub = -1;
 static int local_pos_sub = -1;
-static int flow_pub = -1;
-static int global_position_setpoint_pub = -1;
-static int local_position_setpoint_pub = -1;
+static orb_advert_t flow_pub = -1;
+static orb_advert_t global_position_setpoint_pub = -1;
+static orb_advert_t local_position_setpoint_pub = -1;
 static bool mavlink_hil_enabled = false;
 
 static char mavlink_message_string[51] = {0};

apps/multirotor_att_control/multirotor_att_control_main.c

@@ -119,9 +119,9 @@ mc_thread_main(int argc, char *argv[])
 	/* publish actuator controls */
 	for (unsigned i = 0; i < NUM_ACTUATOR_CONTROLS; i++)
 		actuators.control[i] = 0.0f;
-	int actuator_pub = orb_advertise(ORB_ID_VEHICLE_ATTITUDE_CONTROLS, &actuators);
+	orb_advert_t actuator_pub = orb_advertise(ORB_ID_VEHICLE_ATTITUDE_CONTROLS, &actuators);
 	armed.armed = true;
-	int armed_pub = orb_advertise(ORB_ID(actuator_armed), &armed);
+	orb_advert_t armed_pub = orb_advertise(ORB_ID(actuator_armed), &armed);
 
 	/* register the perf counter */
 	perf_counter_t mc_loop_perf = perf_alloc(PC_ELAPSED, "multirotor_att_control");

apps/multirotor_pos_control/multirotor_pos_control.c

@@ -89,7 +89,7 @@ mpc_thread_main(int argc, char *argv[])
 	int local_pos_sp_sub = orb_subscribe(ORB_ID(vehicle_local_position_setpoint));
 
 	/* publish attitude setpoint */
-	int att_sp_pub = orb_advertise(ORB_ID(vehicle_attitude_setpoint), &att_sp);
+	orb_advert_t att_sp_pub = orb_advertise(ORB_ID(vehicle_attitude_setpoint), &att_sp);
 
 	while (1) {
 		/* get a local copy of the vehicle state */

apps/position_estimator/position_estimator_main.c

@@ -297,7 +297,7 @@ int position_estimator_main(int argc, char *argv[])
 		.lon = lon_current * 1e7,
 		.alt = gps.alt
 	};
-	int global_pos_pub = orb_advertise(ORB_ID(vehicle_global_position), &global_pos);
+	orb_advert_t global_pos_pub = orb_advertise(ORB_ID(vehicle_global_position), &global_pos);
 
 	printf("[multirotor position estimator] initialized projection with: lat: %.10f,  lon:%.10f\n", lat_current, lon_current);
 

apps/px4/attitude_estimator_bm/attitude_estimator_bm.c

@@ -154,7 +154,7 @@ int attitude_estimator_bm_main(int argc, char *argv[])
 	bool publishing = false;
 
 	/* advertise attitude */
-	int pub_att = orb_advertise(ORB_ID(vehicle_attitude), &att);
+	orb_advert_t pub_att = orb_advertise(ORB_ID(vehicle_attitude), &att);
 	publishing = true;
 
 	struct pollfd fds[] = {

apps/px4/fmu/fmu.cpp

@@ -89,7 +89,7 @@ private:
 	int		_task;
 	int		_t_actuators;
 	int		_t_armed;
-	int		_t_outputs;
+	orb_advert_t	_t_outputs;
 	unsigned	_num_outputs;
 
 	volatile bool	_task_should_exit;
@@ -566,15 +566,13 @@ fake(int argc, char *argv[])
 
 	ac.control[3] = strtol(argv[4], 0, 0) / 100.0f;
 
-	int handle = orb_advertise(ORB_ID_VEHICLE_ATTITUDE_CONTROLS, &ac);
+	orb_advert_t handle = orb_advertise(ORB_ID_VEHICLE_ATTITUDE_CONTROLS, &ac);
 
 	if (handle < 0) {
 		puts("advertise failed");
 		exit(1);
 	}
 
-	close(handle);
-
 	exit(0);
 }
 

apps/px4/px4io/driver/px4io.cpp

@@ -99,7 +99,7 @@ protected:
 	void			set_channels(unsigned count, const servo_position_t *data);
 
 private:
-	int			_publication;
+	orb_advert_t		_publication;
 	struct rc_input_values	_input;
 };
 

apps/sensors/sensors.c

@@ -124,8 +124,8 @@ extern unsigned ppm_decoded_channels;
 extern uint64_t ppm_last_valid_decode;
 #endif
 
-/* file handle that will be used for subscribing */
-static int sensor_pub;
+/* ORB topic publishing our results */
+static orb_advert_t sensor_pub;
 
 /**
  * Sensor readout and publishing.
@@ -404,7 +404,7 @@ int sensors_thread_main(int argc, char *argv[])
 						   .yaw = 0.0f,
 						   .throttle = 0.0f };
 
-	int manual_control_pub = orb_advertise(ORB_ID(manual_control_setpoint), &manual_control);
+	orb_advert_t manual_control_pub = orb_advertise(ORB_ID(manual_control_setpoint), &manual_control);
 
 	if (manual_control_pub < 0) {
 		fprintf(stderr, "[sensors] ERROR: orb_advertise for topic manual_control_setpoint failed.\n");
@@ -413,7 +413,7 @@ int sensors_thread_main(int argc, char *argv[])
 	/* advertise the rc topic */
 	struct rc_channels_s rc;
 	memset(&rc, 0, sizeof(rc));
-	int rc_pub = orb_advertise(ORB_ID(rc_channels), &rc);
+	orb_advert_t rc_pub = orb_advertise(ORB_ID(rc_channels), &rc);
 
 	if (rc_pub < 0) {
 		fprintf(stderr, "[sensors] ERROR: orb_advertise for topic rc_channels failed.\n");
@@ -466,7 +466,6 @@ int sensors_thread_main(int argc, char *argv[])
 				if (vstatus.flag_hil_enabled && !hil_enabled) {
 					hil_enabled = true;
 					publishing = false;
-					int ret = close(sensor_pub);
 					printf("[sensors] Closing sensor pub: %i \n", ret);
 
 					/* switching from HIL to non-HIL mode */

apps/uORB/uORB.cpp

@@ -112,6 +112,8 @@ public:
 	virtual ssize_t		write(struct file *filp, const char *buffer, size_t buflen);
 	virtual int		ioctl(struct file *filp, int cmd, unsigned long arg);
 
+	static ssize_t		publish(const orb_metadata *meta, orb_advert_t handle, const void *data);
+
 protected:
 	virtual pollevent_t	poll_state(struct file *filp);
 	virtual void		poll_notify_one(struct pollfd *fds, pollevent_t events);
@@ -298,6 +300,8 @@ ORBDevNode::write(struct file *filp, const char *buffer, size_t buflen)
 	 *
 	 * Writes outside interrupt context will allocate the object
 	 * if it has not yet been allocated.
+	 *
+	 * Note that filp will usually be NULL.
 	 */
 	if (nullptr == _data) {
 		if (!up_interrupt_context()) {
@@ -353,12 +357,42 @@ ORBDevNode::ioctl(struct file *filp, int cmd, unsigned long arg)
 		sd->update_interval = arg;
 		return OK;
 
+	case ORBIOCGADVERTISER:
+		*(uintptr_t *)arg = (uintptr_t)this;
+		return OK;
+
 	default:
 		/* give it to the superclass */
 		return CDev::ioctl(filp, cmd, arg);
 	}
 }
 
+ssize_t
+ORBDevNode::publish(const orb_metadata *meta, orb_advert_t handle, const void *data)
+{
+	ORBDevNode *devnode = (ORBDevNode *)handle;
+	int ret;
+
+	/* this is a bit risky, since we are trusting the handle in order to deref it */
+	if (devnode->_meta != meta) {
+		errno = EINVAL;
+		return ERROR;
+	}
+
+	/* call the devnode write method with no file pointer */
+	ret = devnode->write(nullptr, (const char *)data, meta->o_size);
+
+	if (ret < 0)
+		return ERROR;
+
+	if (ret != (int)meta->o_size) {
+		errno = EIO;
+		return ERROR;
+	}
+
+	return OK;
+}
+
 pollevent_t
 ORBDevNode::poll_state(struct file *filp)
 {
@@ -614,7 +648,7 @@ test()
 	if (pfd < 0)
 		return test_fail("advertise failed: %d", errno);
 
-	test_note("publish fd %d", pfd);
+	test_note("publish handle 0x%08x", pfd);
 	sfd = orb_subscribe(ORB_ID(orb_test));
 
 	if (sfd < 0)
@@ -877,29 +911,35 @@ node_open(Flavor f, const struct orb_metadata *meta, const void *data, bool adve
 		return ERROR;
 	}
 
-	/* the advertiser must perform an initial publish to initialise the object */
-	if (advertiser) {
-		ret = orb_publish(meta, fd, data);
-
-		if (ret != OK) {
-			/* save errno across the close */
-			ret = errno;
-			close(fd);
-			errno = ret;
-			return ERROR;
-		}
-	}
-
 	/* everything has been OK, we can return the handle now */
 	return fd;
 }
 
 } // namespace
 
-int
+orb_advert_t
 orb_advertise(const struct orb_metadata *meta, const void *data)
 {
-	return node_open(PUBSUB, meta, data, true);
+	int result, fd;
+	orb_advert_t advertiser;
+
+	/* open the node as an advertiser */
+	fd = node_open(PUBSUB, meta, data, true);
+	if (fd == ERROR)
+		return ERROR;
+
+	/* get the advertiser handle and close the node */
+	result = ioctl(fd, ORBIOCGADVERTISER, (unsigned long)&advertiser);
+	close(fd);
+	if (result == ERROR)
+		return ERROR;
+
+	/* the advertiser must perform an initial publish to initialise the object */
+	result= orb_publish(meta, advertiser, data);
+	if (result == ERROR)
+		return ERROR;
+
+	return advertiser;
 }
 
 int
@@ -915,21 +955,9 @@ orb_unsubscribe(int handle)
 }
 
 int
-orb_publish(const struct orb_metadata *meta, int handle, const void *data)
+orb_publish(const struct orb_metadata *meta, orb_advert_t handle, const void *data)
 {
-	int ret;
-
-	ret = write(handle, data, meta->o_size);
-
-	if (ret < 0)
-		return ERROR;
-
-	if (ret != (int)meta->o_size) {
-		errno = EIO;
-		return ERROR;
-	}
-
-	return OK;
+	return ORBDevNode::publish(meta, handle, data);
 }
 
 int

apps/uORB/uORB.h

@@ -105,12 +105,27 @@ struct orb_metadata {
 
 __BEGIN_DECLS
 
+/**
+ * ORB topic advertiser handle.
+ *
+ * Advertiser handles are global; once obtained they can be shared freely
+ * and do not need to be closed or released.
+ *
+ * This permits publication from interrupt context and other contexts where
+ * a file-descriptor-based handle would not otherwise be in scope for the
+ * publisher.
+ */
+typedef intptr_t	orb_advert_t;
+
 /**
  * Advertise as the publisher of a topic.
  *
  * This performs the initial advertisement of a topic; it creates the topic
  * node in /obj if required and publishes the initial data.
  *
+ * Any number of advertisers may publish to a topic; publications are atomic
+ * but co-ordination between publishers is not provided by the ORB. 
+ *
  * @param meta		The uORB metadata (usually from the ORB_ID() macro)
  *			for the topic.
  * @param data		A pointer to the initial data to be published.
@@ -122,7 +137,7 @@ __BEGIN_DECLS
  *			ORB_DEFINE with no corresponding ORB_DECLARE)
  *			this function will return -1 and set errno to ENOENT.
  */
-extern int	orb_advertise(const struct orb_metadata *meta, const void *data) __EXPORT;
+extern orb_advert_t orb_advertise(const struct orb_metadata *meta, const void *data) __EXPORT;
 
 /**
  * Publish new data to a topic.
@@ -131,13 +146,13 @@ extern int	orb_advertise(const struct orb_metadata *meta, const void *data) __EX
  * will be notified.  Subscribers that are not waiting can check the topic
  * for updates using orb_check and/or orb_stat.
  *
- * @handle		The handle returned from orb_advertise.
  * @param meta		The uORB metadata (usually from the ORB_ID() macro)
  *			for the topic.
+ * @handle		The handle returned from orb_advertise.
  * @param data		A pointer to the data to be published.
  * @return		OK on success, ERROR otherwise with errno set accordingly.
  */
-extern int	orb_publish(const struct orb_metadata *meta, int handle, const void *data) __EXPORT;
+extern int	orb_publish(const struct orb_metadata *meta, orb_advert_t handle, const void *data) __EXPORT;
 
 /**
  * Subscribe to a topic.