evl/thread: drop evl_start_thread() from the kernel API

EVL threads start running immediately after creation, there is no need
for an intermediate stopped state.

Let's open code the few bits required to set up the scheduling state
of an emerging user/kernel thread instead, and get rid of this Cobalt
legacy.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

include/evenless/thread.h

@@ -214,8 +214,6 @@ int evl_init_thread(struct evl_thread *thread,
 		struct evl_rq *rq,
 		const char *fmt, ...);
 
-void evl_start_thread(struct evl_thread *thread);
-
 void evl_sleep_on(ktime_t timeout, enum evl_tmode timeout_mode,
 		struct evl_clock *clock,
 		struct evl_wait_channel *wchan);

include/trace/events/evenless.h

@@ -439,11 +439,6 @@ TRACE_EVENT(evl_thread_set_current_prio,
 		  __entry->thread, __entry->pid, __entry->cprio)
 );
 
-DEFINE_EVENT(curr_thread_event, evl_thread_start,
-	TP_PROTO(struct evl_thread *thread),
-	TP_ARGS(thread)
-);
-
 DEFINE_EVENT(thread_event, evl_thread_cancel,
 	TP_PROTO(struct evl_thread *thread),
 	TP_ARGS(thread)

kernel/evenless/thread.c

@@ -64,8 +64,12 @@ static void periodic_handler(struct evl_timer *timer) /* hard irqs off */
 
 static inline void enlist_new_thread(struct evl_thread *thread)
 {				/* nklock held, irqs off */
+	unsigned long flags;
+
+	xnlock_get_irqsave(&nklock, flags);
 	list_add_tail(&thread->next, &evl_thread_list);
 	evl_nrthreads++;
+	xnlock_put_irqrestore(&nklock, flags);
 }
 
 static inline void set_oob_threadinfo(struct evl_thread *thread)
@@ -299,7 +303,6 @@ static void wakeup_kthread_parent(struct irq_work *irq_work)
 static int map_kthread_self(struct evl_kthread *kthread)
 {
 	struct evl_thread *curr = &kthread->thread;
-	unsigned long flags;
 
 	pin_to_initial_cpu(curr);
 
@@ -328,9 +331,7 @@ static int map_kthread_self(struct evl_kthread *kthread)
 	init_irq_work(&kthread->irq_work, wakeup_kthread_parent);
 	irq_work_queue(&kthread->irq_work);
 
-	xnlock_get_irqsave(&nklock, flags);
 	enlist_new_thread(curr);
-	xnlock_put_irqrestore(&nklock, flags);
 	evl_hold_thread(curr, T_DORMANT);
 
 	return kthread->status;
@@ -402,7 +403,8 @@ int __evl_run_kthread(struct evl_kthread *kthread)
 	if (kthread->status)
 		return kthread->status;
 
-	evl_start_thread(thread);
+	evl_release_thread(thread, T_DORMANT, 0);
+	evl_schedule();
 
 	return 0;
 
@@ -417,32 +419,6 @@ int __evl_run_kthread(struct evl_kthread *kthread)
 }
 EXPORT_SYMBOL_GPL(__evl_run_kthread);
 
-void evl_start_thread(struct evl_thread *thread)
-{
-	unsigned long flags;
-
-	xnlock_get_irqsave(&nklock, flags);
-
-	/*
-	 * A user-space thread starts immediately EVL-wise since we
-	 * already have an underlying in-band context for it, so we
-	 * can enlist it now.
-	 *
-	 * NOTE: starting an already started thread moves it to the
-	 * head of the runqueue if running, nop otherwise.
-	 */
-	if ((thread->state & (T_DORMANT|T_USER)) == (T_DORMANT|T_USER))
-		enlist_new_thread(thread);
-
-	trace_evl_thread_start(thread);
-	evl_release_thread(thread, T_DORMANT, 0);
-
-	xnlock_put_irqrestore(&nklock, flags);
-
-	evl_schedule();
-}
-EXPORT_SYMBOL_GPL(evl_start_thread);
-
 static inline void abort_wait(struct evl_thread *thread)
 {
 	struct evl_wait_channel *wchan = thread->wchan;
@@ -2206,7 +2182,14 @@ static int map_uthread_self(struct evl_thread *thread)
 	 * debug code from handle_schedule_event() and friends.
 	 */
 	dovetail_start_altsched();
-	evl_start_thread(thread);
+
+	/*
+	 * A user-space thread is already started EVL-wise since we
+	 * have an underlying in-band context for it, so we can enlist
+	 * it now.
+	 */
+	enlist_new_thread(thread);
+	evl_release_thread(thread, T_DORMANT, 0);
 	evl_sync_uwindow(thread);
 
 	return 0;