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.

2 files changed, 76 insertions, 33 deletions

diff --git a/apps/uORB/uORB.cpp b/apps/uORB/uORB.cpp
index 1e7cdc8db..c4434e4ed 100644
--- a/apps/uORB/uORB.cpp
+++ b/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
diff --git a/apps/uORB/uORB.h b/apps/uORB/uORB.h
index c36d0044f..eb068d2b7 100644
--- a/apps/uORB/uORB.h
+++ b/apps/uORB/uORB.h
@@ -106,11 +106,26 @@ 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.