platforms/nuttx: Remove unnecessary sched_lock() from task spawn logic

Starting a new task does not require that the scheduler is locked, this is
done in nsh only because nsh uses waitpid() to wait for the task to exit
and record its exit status.

The exit status does not interest us whatsoever -> remove the locking.

Also, we don't need to explicitly change a tasks priority when it is
created by px4_task_spawn_cmd, as task_create() already sets the priority
via nxthread_setup_scheduler().

platforms/nuttx/src/px4/common/cdc_acm_check.cpp

@@ -336,25 +336,19 @@ static void mavlink_usb_check(void *arg)
 #if defined(CONFIG_SERIAL_PASSTHRU_UBLOX)
 
 								else if (launch_passthru) {
-									sched_lock();
 									exec_argv = (char **)gps_argv;
 									px4_exec(exec_argv[0], exec_argv, nullptr, 0);
-									sched_unlock();
 									exec_argv = (char **)passthru_argv;
 								}
 
 #endif
 
-								sched_lock();
-
 								if (px4_exec(exec_argv[0], exec_argv, nullptr, 0) > 0) {
 									usb_auto_start_state = UsbAutoStartState::connected;
 
 								} else {
 									usb_auto_start_state = UsbAutoStartState::disconnecting;
 								}
-
-								sched_unlock();
 							}
 						}
 					}
@@ -374,10 +368,8 @@ static void mavlink_usb_check(void *arg)
 
 		case UsbAutoStartState::connected:
 			if (!vbus_present && !vbus_present_prev) {
-				sched_lock();
 				static const char *stop_argv[] {"mavlink", "stop", "-d", USB_DEVICE_PATH, NULL};
 				px4_exec(stop_argv[0], (char **)stop_argv, NULL, 0);
-				sched_unlock();
 
 				usb_auto_start_state = UsbAutoStartState::disconnecting;
 			}

platforms/nuttx/src/px4/common/tasks.cpp

@@ -64,8 +64,6 @@
 
 int px4_task_spawn_cmd(const char *name, int scheduler, int priority, int stack_size, main_t entry, char *const argv[])
 {
-	sched_lock();
-
 #if !defined(CONFIG_DISABLE_ENVIRON) && !defined(CONFIG_BUILD_KERNEL)
 	/* None of the modules access the environment variables (via getenv() for instance), so delete them
 	 * all. They are only used within the startup script, and NuttX automatically exports them to the children
@@ -82,14 +80,6 @@ int px4_task_spawn_cmd(const char *name, int scheduler, int priority, int stack_
 	int pid = kthread_create(name, priority, stack_size, entry, argv);
 #endif
 
-	if (pid > 0) {
-		/* configure the scheduler */
-		struct sched_param param = { .sched_priority = priority };
-		sched_setscheduler(pid, scheduler, &param);
-	}
-
-	sched_unlock();
-
 	return pid;
 }