Make sure we can submit tasks from codelets and callbacks

doc/chapters/basic-api.texi

@@ -1582,6 +1582,10 @@ function for instance.
 In case of success, this function returns 0, a return value of @code{-ENODEV}
 means that there is no worker able to process this task (e.g. there is no GPU
 available and this task is only implemented for CUDA devices).
+
+starpu_task_submit() can be called from anywhere, including codelet
+functions and callbacks, provided that the @code{synchronous} field of the
+@code{starpu_task} structure is left to 0.
 @end deftypefun
 
 @deftypefun int starpu_task_wait_for_all (void)

tests/Makefile.am

@@ -141,7 +141,8 @@ noinst_PROGRAMS =				\
 	main/declare_deps_after_submission_synchronous	\
 	main/get_current_task			\
 	main/starpu_init			\
-	main/starpu_worker_exists               \
+	main/starpu_worker_exists		\
+	main/submit				\
 	datawizard/acquire_cb			\
 	datawizard/acquire_cb_insert		\
 	datawizard/acquire_release		\

tests/main/submit.c

@@ -0,0 +1,115 @@
+/* StarPU --- Runtime system for heterogeneous multicore architectures.
+ *
+ * Copyright (C) 2010-2012  Université de Bordeaux 1
+ * Copyright (C) 2010, 2011, 2012  Centre National de la Recherche Scientifique
+ *
+ * StarPU is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or (at
+ * your option) any later version.
+ *
+ * StarPU is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * See the GNU Lesser General Public License in COPYING.LGPL for more details.
+ */
+
+#include <sys/time.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <pthread.h>
+#include <starpu.h>
+#include "../helper.h"
+
+static int i = 0, j;
+
+static void dummy_func(void *descr[] __attribute__ ((unused)), void *arg __attribute__ ((unused)))
+{
+	i++;
+	FPRINTF(stdout, "called third task, i = %d\n", i);
+}
+
+static struct starpu_codelet dummy_codelet = 
+{
+	.where = STARPU_CPU|STARPU_CUDA|STARPU_OPENCL,
+	.cpu_funcs = {dummy_func, NULL},
+	.cuda_funcs = {dummy_func, NULL},
+	.opencl_funcs = {dummy_func, NULL},
+	.model = NULL,
+	.nbuffers = 0
+};
+
+static void callback(void *arg __attribute__ ((unused)))
+{
+	struct starpu_task *task = starpu_task_create();
+	task->cl = &dummy_codelet;
+	task->detach = 1;
+	if (starpu_task_submit(task) == ENODEV)
+		exit(STARPU_TEST_SKIPPED);
+	FPRINTF(stdout, "submitted third task, i = %d\n", i);
+}
+
+static struct starpu_codelet callback_submit_codelet = 
+{
+	.where = STARPU_CPU|STARPU_CUDA|STARPU_OPENCL,
+	.cpu_funcs = {dummy_func, NULL},
+	.cuda_funcs = {dummy_func, NULL},
+	.opencl_funcs = {dummy_func, NULL},
+	.model = NULL,
+	.nbuffers = 0
+};
+
+static void task_submit_func(void *descr[] __attribute__ ((unused)), void *arg __attribute__ ((unused)))
+{
+	struct starpu_task *task = starpu_task_create();
+	task->cl = &callback_submit_codelet;
+	task->callback_func = callback;
+	task->detach = 1;
+	if (starpu_task_submit(task) == ENODEV)
+		exit(STARPU_TEST_SKIPPED);
+	i++;
+	FPRINTF(stdout, "submitted second task, i = %d\n", i);
+}
+
+static struct starpu_codelet task_submit_codelet = 
+{
+	.where = STARPU_CPU|STARPU_CUDA|STARPU_OPENCL,
+	.cpu_funcs = {task_submit_func, NULL},
+	.cuda_funcs = {task_submit_func, NULL},
+	.opencl_funcs = {task_submit_func, NULL},
+	.model = NULL,
+	.nbuffers = 0
+};
+
+int main(int argc, char **argv)
+{
+	int ret;
+
+	ret = starpu_init(NULL);
+	if (ret == -ENODEV) return STARPU_TEST_SKIPPED;
+	STARPU_CHECK_RETURN_VALUE(ret, "starpu_init");
+
+	struct starpu_task *task = starpu_task_create();
+
+	task->cl = &task_submit_codelet;
+	task->detach = 1;
+
+	ret = starpu_task_submit(task);
+	if (ret == -ENODEV) goto enodev;
+	STARPU_CHECK_RETURN_VALUE(ret, "starpu_task_submit");
+
+	starpu_task_wait_for_all();
+	j = i;
+
+	starpu_shutdown();
+
+	return j == 3 ? EXIT_SUCCESS : EXIT_FAILURE;
+
+enodev:
+	fprintf(stderr, "WARNING: No one can execute this task\n");
+	/* yes, we do not perform the computation but we did detect that no one
+ 	 * could perform the kernel, so this is not an error from StarPU */
+	starpu_shutdown();
+	return STARPU_TEST_SKIPPED;
+}