uORB: Remove transfer of memory allocation ownership to CDev

- Allocate and free the node name in uORBDeviceNode.
- Add protected build support by de-allocating the name with kmm_free, when
  running in kernel side. strdup allocates from the kernel heap in NuttX kernel
  space.
- Remove the CDev::unregister_driver_and_memory(), it is no longer used

Signed-off-by: Jukka Laitinen <jukkax@ssrc.tii.ae>

platforms/common/uORB/uORBDeviceMaster.cpp

@@ -99,19 +99,11 @@ int uORB::DeviceMaster::advertise(const struct orb_metadata *meta, bool is_adver
 			*instance = group_tries;
 		}
 
-		/* driver wants a permanent copy of the path, so make one here */
-		const char *devpath = strdup(nodepath);
-
-		if (devpath == nullptr) {
-			return -ENOMEM;
-		}
-
 		/* construct the new node, passing the ownership of path to it */
-		uORB::DeviceNode *node = new uORB::DeviceNode(meta, group_tries, devpath);
+		uORB::DeviceNode *node = new uORB::DeviceNode(meta, group_tries, nodepath);
 
-		/* if we didn't get a device, that's bad, free the path too */
+		/* if we didn't get a device, that's bad */
 		if (node == nullptr) {
-			free((void *)devpath);
 			return -ENOMEM;
 		}
 

platforms/common/uORB/uORBDeviceNode.cpp

@@ -42,6 +42,10 @@
 #include "uORBCommunicator.hpp"
 #endif /* ORB_COMMUNICATOR */
 
+#if defined(__PX4_NUTTX)
+#include <nuttx/mm/mm.h>
+#endif
+
 static uORB::SubscriptionInterval *filp_to_subscription(cdev::file_t *filp) { return static_cast<uORB::SubscriptionInterval *>(filp->f_priv); }
 
 // round up to nearest power of two
@@ -71,7 +75,7 @@ static inline uint8_t round_pow_of_two_8(uint8_t n)
 
 uORB::DeviceNode::DeviceNode(const struct orb_metadata *meta, const uint8_t instance, const char *path,
 			     uint8_t queue_size) :
-	CDev(path),
+	CDev(strdup(path)), // success is checked in CDev::init
 	_meta(meta),
 	_instance(instance),
 	_queue_size(round_pow_of_two_8(queue_size))
@@ -82,7 +86,15 @@ uORB::DeviceNode::~DeviceNode()
 {
 	delete[] _data;
 
-	CDev::unregister_driver_and_memory();
+	const char *devname = get_devname();
+
+	if (devname) {
+#if defined(__PX4_NUTTX) && !defined(CONFIG_BUILD_FLAT)
+		kmm_free((void *)devname);
+#else
+		free((void *)devname);
+#endif
+	}
 }
 
 int

src/lib/cdev/CDev.cpp

@@ -128,6 +128,9 @@ CDev::init()
 		if (ret == PX4_OK) {
 			_registered = true;
 		}
+
+	} else {
+		ret = -ENODEV;
 	}
 
 	return ret;
@@ -373,27 +376,4 @@ CDev::remove_poll_waiter(px4_pollfd_struct_t *fds)
 	return -EINVAL;
 }
 
-int CDev::unregister_driver_and_memory()
-{
-	int retval = PX4_OK;
-
-	if (_registered) {
-		unregister_driver(_devname);
-		_registered = false;
-
-	} else {
-		retval = -ENODEV;
-	}
-
-	if (_devname != nullptr) {
-		free((void *)_devname);
-		_devname = nullptr;
-
-	} else {
-		retval = -ENODEV;
-	}
-
-	return retval;
-}
-
 } // namespace cdev

src/lib/cdev/CDev.hpp

@@ -270,17 +270,6 @@ protected:
 
 	px4_sem_t	_lock; /**< lock to protect access to all class members (also for derived classes) */
 
-
-	/**
-	* First, unregisters the driver. Next, free the memory for the devname,
-	* in case it was expected to have ownership. Sets devname to nullptr.
-	*
-	* This is only needed if the ownership of the devname was passed to the CDev, otherwise ~CDev handles it.
-	*
-	* @return  PX4_OK on success, -ENODEV if the devname is already nullptr
-	*/
-	int unregister_driver_and_memory();
-
 private:
 	const char	*_devname{nullptr};		/**< device node name */