gpu: nvgpu: posix: Multithreading for unit tests

Add a -j argument to enable running unit tests on several
threads. Also adds signal handling to prevent a fatal
error in one thread from killing the whole unit test
framework.

JIRA NVGPU-1043

Change-Id: I891a547640cd005a50ffa5c06367ed46c54de012
Signed-off-by: Nicolas Benech <nbenech@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1847740
Reviewed-by: svc-misra-checker <svc-misra-checker@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Alex Waterman <alexw@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

userspace/src/args.c

@@ -36,11 +36,12 @@ static struct option core_opts[] = {
 	{ "no-color",		0, NULL, 'C' },
 
 	{ "unit-load-path",	1, NULL, 'L' },
+	{ "num-threads",	1, NULL, 'j' },
 
 	{ NULL,			0, NULL,  0  }
 };
 
-static const char *core_opts_str = "hvqCL:";
+static const char *core_opts_str = "hvqCL:j:";
 
 void core_print_help(struct unit_fw *fw)
 {
@@ -63,6 +64,8 @@ void core_print_help(struct unit_fw *fw)
 "                         corrupt that file.\n",
 "  -L, --unit-load-path <PATH>\n",
 "                         Path to where the unit test libraries reside.\n",
+"  -j, --num-threads <COUNT>\n",
+"                         Number of threads to use while running all tests.\n",
 "\n",
 "Note: mandatory arguments to long arguments are mandatory for short\n",
 "arguments as well.\n",
@@ -79,6 +82,7 @@ NULL
 static void set_arg_defaults(struct unit_fw_args *args)
 {
 	args->unit_load_path = DEFAULT_ARG_UNIT_LOAD_PATH;
+	args->thread_count = 1;
 }
 
 /*
@@ -121,6 +125,13 @@ int core_parse_args(struct unit_fw *fw, int argc, char **argv)
 		case 'L':
 			args->unit_load_path = optarg;
 			break;
+		case 'j':
+			args->thread_count = strtol(optarg, NULL, 10);
+			if (args->thread_count == 0) {
+				core_err(fw, "Invalid number of threads\n");
+				return -1;
+			}
+			break;
 		case '?':
 			args->help = true;
 			return -1;

userspace/src/exec.c

@@ -21,6 +21,10 @@
  */
 
 #include <stdlib.h>
+#include <string.h>
+#include <pthread.h>
+#include <semaphore.h>
+#include <signal.h>
 
 #include <unit/io.h>
 #include <unit/core.h>
@@ -30,20 +34,40 @@
 
 #include <nvgpu/posix/probe.h>
 
+/*
+ * Sempaphore to limit the number of threads
+ */
+sem_t unit_thread_semaphore;
+
+/*
+ * C11 thread local storage, used to access test context when a signal is
+ * received (ex: SIGSEGV) in a thread.
+ */
+_Thread_local struct unit_module *thread_local_module;
+_Thread_local struct unit_module_test *thread_local_test;
+
 /*
  * Execute a module and all its subtests. This function builds a gk20a for the
  * test to use by executing nvgpu_posix_probe() and nvgpu_posix_cleanup();
  */
-static int core_exec_module(struct unit_fw *fw,
-			    struct unit_module *module)
+static void *core_exec_module(void *module_param)
 {
 	unsigned int i;
-	struct gk20a *g = fw->nvgpu.nvgpu_posix_probe();
+	struct unit_module *module = (struct unit_module *) module_param;
+	struct gk20a *g;
 
-	if (!g)
-		return -1;
+	g = module->fw->nvgpu.nvgpu_posix_probe();
 
-	core_vbs(fw, 1, "Execing module: %s\n", module->name);
+	if (!g) {
+		core_msg_color(module->fw, C_RED,
+				"  nvgpu_posix_probe failed: Module %s\n",
+				module->name);
+		goto thread_exit;
+	}
+
+	core_vbs(module->fw, 1, "Execing module: %s\n", module->name);
+
+	thread_local_module = module;
 
 	/*
 	 * Execute each test within the module. No reinit is done between tests.
@@ -53,21 +77,86 @@ static int core_exec_module(struct unit_fw *fw,
 	for (i = 0; i < module->nr_tests; i++) {
 		struct unit_module_test *t = module->tests + i;
 		int test_status;
+		thread_local_test = t;
 
-		core_msg(fw, "Running %s.%s\n", module->name, t->name);
+		core_msg(module->fw, "Running %s.%s\n", module->name,
+			t->name);
 		test_status = t->fn(module, g, t->args);
 
 		if (test_status != UNIT_SUCCESS)
-			core_msg_color(fw, C_RED,
+			core_msg_color(module->fw, C_RED,
 				       "  Unit error! Test %s.%s FAILED!\n",
 				       module->name, t->name);
 
-		core_add_test_record(fw, module, t,
+		core_add_test_record(module->fw, module, t,
 				     test_status == UNIT_SUCCESS);
 	}
 
-	fw->nvgpu.nvgpu_posix_cleanup(g);
+	module->fw->nvgpu.nvgpu_posix_cleanup(g);
 
+	core_vbs(module->fw, 1, "Module completed: %s\n", module->name);
+thread_exit:
+	sem_post(&unit_thread_semaphore);
+	return NULL;
+}
+
+/*
+ * According to POSIX, "Signals which are generated by some action attributable
+ * to a particular thread, such as a hardware fault, shall be generated for the
+ * thread that caused the signal to be generated."
+ * This custom signal handler will be run from within the thread that caused the
+ * exception. Thanks to the context being saved in local thread storage, it is
+ * then trivial to report which test case failed, and then terminate the thread.
+ */
+static void thread_error_handler(int sig, siginfo_t *siginfo, void *context)
+{
+	core_msg_color(thread_local_module->fw, C_RED,
+			"  Signal %d in Test: %s.%s!\n", sig,
+			thread_local_module->name, thread_local_test->name);
+	core_add_test_record(thread_local_module->fw, thread_local_module,
+			thread_local_test, false);
+	sem_post(&unit_thread_semaphore);
+	pthread_exit(NULL);
+}
+
+/*
+ * Install a custom signal handler for several signals to be used when running
+ * in multithreaded environment.
+ */
+static int install_thread_error_handler(void)
+{
+	struct sigaction action;
+	int err;
+
+	memset(&action, 0, sizeof(action));
+	action.sa_sigaction = &thread_error_handler;
+	action.sa_flags = SA_SIGINFO;
+
+	/* SIGSEGV: Invalid memory reference */
+	err = sigaction(SIGSEGV, &action, NULL);
+	if (err < 0) {
+		return err;
+	}
+	/* SIGILL: Illegal Instruction */
+	err = sigaction(SIGILL, &action, NULL);
+	if (err < 0) {
+		return err;
+	}
+	/* SIGFPE: Floating-point exception */
+	err = sigaction(SIGFPE, &action, NULL);
+	if (err < 0) {
+		return err;
+	}
+	/* SIGBUS: Bus error */
+	err = sigaction(SIGBUS, &action, NULL);
+	if (err < 0) {
+		return err;
+	}
+	/* SIGSYS: Bad system call */
+	err = sigaction(SIGSYS, &action, NULL);
+	if (err < 0) {
+		return err;
+	}
 	return 0;
 }
 
@@ -76,14 +165,39 @@ static int core_exec_module(struct unit_fw *fw,
  */
 int core_exec(struct unit_fw *fw)
 {
-	int ret;
 	struct unit_module **modules;
+	int err = 0;
+
+	core_vbs(fw, 1, "Using %d threads\n", fw->args->thread_count);
+	sem_init(&unit_thread_semaphore, 0, fw->args->thread_count);
+
+	/*
+	 * If running single threaded, keep the default SIGSEGV handler to make
+	 * interactive debugging easier, otherwise install the custom one.
+	 */
+	if (fw->args->thread_count > 1) {
+		err = install_thread_error_handler();
+		if (err != 0) {
+			core_msg_color(fw, C_RED,
+			"  Failed to install signal handler!\n");
+			return err;
+		}
+	}
 
 	for (modules = fw->modules; *modules != NULL; modules++) {
-		ret = core_exec_module(fw, *modules);
+		if (fw->args->thread_count == 1) {
+			core_exec_module(*modules);
+		} else {
+			sem_wait(&unit_thread_semaphore);
+			pthread_create(&((*modules)->thread), NULL,
+				core_exec_module, (void *) *modules);
+		}
+	}
 
-		if (ret != 0)
-			return ret;
+	if (fw->args->thread_count > 1) {
+		for (modules = fw->modules; *modules != NULL; modules++) {
+			pthread_join((*modules)->thread, NULL);
+		}
 	}
 
 	return 0;

userspace/src/results.c

@@ -22,12 +22,18 @@
 
 #include <stdlib.h>
 #include <string.h>
+#include <pthread.h>
 
 #include <unit/io.h>
 #include <unit/core.h>
 #include <unit/unit.h>
 #include <unit/results.h>
 
+/*
+ * Mutex to ensure core_add_test_record() is thread safe.
+ */
+pthread_mutex_t mutex_results = PTHREAD_MUTEX_INITIALIZER;
+
 static int __init_results(struct unit_fw *fw)
 {
 	struct unit_results *results;
@@ -72,16 +78,22 @@ int core_add_test_record(struct unit_fw *fw,
 			 bool success)
 {
 	struct unit_test_record *tr;
+	int err = 0;
 
+	pthread_mutex_lock(&mutex_results);
 	/*
-	 * Dones nothing if results are already inited.
+	 * Does nothing if results are already inited.
 	 */
-	if (__init_results(fw) != 0)
-		return -1;
+	if (__init_results(fw) != 0) {
+		err = -1;
+		goto done;
+	}
 
 	tr = malloc(sizeof(*tr));
-	if (tr == NULL)
-		return -1;
+	if (tr == NULL) {
+		err = -1;
+		goto done;
+	}
 
 	tr->mod = mod;
 	tr->test = test;
@@ -97,7 +109,9 @@ int core_add_test_record(struct unit_fw *fw,
 	if (success)
 		fw->results->nr_passing += 1;
 
-	return 0;
+done:
+	pthread_mutex_unlock(&mutex_results);
+	return err;
 }
 
 void core_print_test_status(struct unit_fw *fw)

userspace/src/unit_main.c

@@ -72,5 +72,13 @@ int main(int argc, char **argv)
 
 	core_print_test_status(fw);
 
+	if (fw->results->nr_tests == 0) {
+		/* No tests were run */
+		return -1;
+	} else if ((fw->results->nr_tests - fw->results->nr_passing) != 0) {
+		/* Some tests failed */
+		return -1;
+	}
+
 	return 0;
 }