hooks: Move HOOK_INIT to after task switching.

This commit changes the way in which tasks are started.  Instead of
having all tasks marked as ready to run upon initialization, only the
hooks task is marked as ready to run.  HOOK_INITs are now run at the
beginning of the hooks task.  After the HOOK_INITs, the hooks task calls
back to enable the rest of the tasks, reschedules, and proceeds as
usual.  This also allows the removal of checks for task_start_called().

BUG=chrome-os-partner:27226
BRANCH=None
TEST=Built and flash EC image for samus and verified that EC boot was
successful as well as AP boot.  Additionally, verified that charging,
keyboard, tap-for-battery were all still functional.
TEST=make -j buildall tests

Change-Id: Iea53670222c803c2985e9c86c96974386888a4fe
Signed-off-by: Aseda Aboagye <aaboagye@google.com>
Reviewed-on: https://chromium-review.googlesource.com/283657
Reviewed-by: Alec Berg <alecaberg@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
Commit-Queue: Aseda Aboagye <aaboagye@chromium.org>
Tested-by: Aseda Aboagye <aaboagye@chromium.org>

2 files changed, 66 insertions, 16 deletions

diff --git a/core/host/main.c b/core/host/main.c
index 80c2f33bf5..fbb28d9127 100644
--- a/core/host/main.c
+++ b/core/host/main.c
@@ -45,7 +45,6 @@ int main(int argc, char **argv)
 #ifdef HAS_TASK_KEYSCAN
 	keyboard_scan_init();
 #endif
-	hook_init();
 	uart_init();
 
 	if (system_jumped_to_this_image()) {
diff --git a/core/host/task.c b/core/host/task.c
index 53f722e8b7..28c0cb0297 100644
--- a/core/host/task.c
+++ b/core/host/task.c
@@ -56,6 +56,8 @@ static int has_interrupt_generator = 1;
 
 static __thread task_id_t my_task_id; /* thread local task id */
 
+static void task_enable_all_tasks_callback(void);
+
 #define TASK(n, r, d, s) void r(void *);
 CONFIG_TASK_LIST
 CONFIG_TEST_TASK_LIST
@@ -331,6 +333,7 @@ static int fast_forward(void)
 		return TASK_ID_IDLE;
 
 	if (task_id != TASK_ID_INVALID &&
+	    tasks[task_id].thread != (pthread_t)NULL &&
 	    tasks[task_id].wake_time.val < generator_sleep_deadline.val) {
 		force_time(tasks[task_id].wake_time);
 		return task_id;
@@ -356,8 +359,15 @@ void task_scheduler(void)
 		now = get_time();
 		i = TASK_ID_COUNT - 1;
 		while (i >= 0) {
-			if (tasks[i].event || now.val >= tasks[i].wake_time.val)
-				break;
+			/*
+			 * Only tasks with spawned threads are valid to be
+			 * resumed.
+			 */
+			if (tasks[i].thread) {
+				if (tasks[i].event ||
+				    now.val >= tasks[i].wake_time.val)
+					break;
+			}
 			--i;
 		}
 		if (i < 0)
@@ -404,7 +414,7 @@ void *_task_int_generator_start(void *d)
 
 int task_start(void)
 {
-	int i;
+	int i = TASK_ID_HOOKS;
 
 	task_register_interrupt();
 
@@ -414,31 +424,72 @@ int task_start(void)
 
 	pthread_mutex_lock(&run_lock);
 
+	/*
+	 * Initialize the hooks task first.  After its init, it will callback to
+	 * enable the remaining tasks.
+	 */
+	tasks[i].event = TASK_EVENT_WAKE;
+	tasks[i].wake_time.val = ~0ull;
+	tasks[i].started = 0;
+	pthread_cond_init(&tasks[i].resume, NULL);
+	pthread_create(&tasks[i].thread, NULL, _task_start_impl,
+		       (void *)(uintptr_t)i);
+	pthread_cond_wait(&scheduler_cond, &run_lock);
+	/*
+	 * Interrupt lock is grabbed by the task which just started.
+	 * Let's unlock it so the next task can be started.
+	 */
+	pthread_mutex_unlock(&interrupt_lock);
+
+	/*
+	 * The hooks task is  waiting in task_wait_event(). Lock interrupt_lock
+	 * here so the first task chosen sees it locked.
+	 */
+	pthread_mutex_lock(&interrupt_lock);
+
+	pthread_create(&interrupt_thread, NULL,
+		       _task_int_generator_start, NULL);
+
+	/*
+	 * Tell the hooks task to continue so that it can call back to enable
+	 * the other tasks.
+	 */
+	pthread_cond_signal(&tasks[i].resume);
+	pthread_cond_wait(&scheduler_cond, &run_lock);
+	task_enable_all_tasks_callback();
+
+	task_scheduler();
+
+	return 0;
+}
+
+static void task_enable_all_tasks_callback(void)
+{
+	int i;
+
+	/* Initialize the remaning tasks. */
 	for (i = 0; i < TASK_ID_COUNT; ++i) {
+		if (tasks[i].thread != (pthread_t)NULL)
+			continue;
+
 		tasks[i].event = TASK_EVENT_WAKE;
 		tasks[i].wake_time.val = ~0ull;
 		tasks[i].started = 0;
 		pthread_cond_init(&tasks[i].resume, NULL);
 		pthread_create(&tasks[i].thread, NULL, _task_start_impl,
 			       (void *)(uintptr_t)i);
-		pthread_cond_wait(&scheduler_cond, &run_lock);
 		/*
 		 * Interrupt lock is grabbed by the task which just started.
 		 * Let's unlock it so the next task can be started.
 		 */
 		pthread_mutex_unlock(&interrupt_lock);
+		pthread_cond_wait(&scheduler_cond, &run_lock);
 	}
 
-	/*
-	 * All tasks are now waiting in task_wait_event(). Lock interrupt_lock
-	 * here so the first task chosen sees it locked.
-	 */
-	pthread_mutex_lock(&interrupt_lock);
-
-	pthread_create(&interrupt_thread, NULL,
-		       _task_int_generator_start, NULL);
-
-	task_scheduler();
+}
 
-	return 0;
+void task_enable_all_tasks(void)
+{
+	/* Signal to the scheduler to enable the remaining tasks. */
+	pthread_cond_signal(&scheduler_cond);
 }