From eec39c5f50fb1b4e2025025773f77293f3466492 Mon Sep 17 00:00:00 2001
From: Flávio Cruz <flaviocruz@gmail.com>
Date: Fri, 28 Aug 2015 01:19:32 +0200
Subject: Add a thread_no_continuation definition

to replace the use of the NULL pointer.

* kern/sched_prim.h (thread_no_continuation): New macro.
* kern/machine.c (processor_assign, processor_doaction): Use
thread_no_continuation instead of 0.
* kern/profile.c (send_last_sample_buf): Likewise
* kern/sched_prim.c (thread_sleep, thread_invoke, thread_dispatch):
Likewise.
* kern/task.c (task_terminate, task_assign): Likewise.
* kern/thread.c (thread_suspend): Likewise.
* kern/thread.h (struct thread): Change type of swap_func field to
continuation_t.
---
 kern/machine.c    | 8 ++++----
 kern/profile.c    | 2 +-
 kern/sched_prim.c | 8 ++++----
 kern/sched_prim.h | 2 ++
 kern/task.c       | 4 ++--
 kern/thread.c     | 2 +-
 kern/thread.h     | 2 +-
 7 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/kern/machine.c b/kern/machine.c
index eced7688..3f7a7f7f 100644
--- a/kern/machine.c
+++ b/kern/machine.c
@@ -270,7 +270,7 @@ Retry:
 	assert_wait((event_t) processor, TRUE);
 	processor_unlock(processor);
 	splx(s);
-	thread_block((void(*)()) 0);
+	thread_block(thread_no_continuation);
 	goto Retry;
     }
 	 
@@ -299,7 +299,7 @@ Retry:
 		assert_wait((event_t)processor, TRUE);
 		processor_unlock(processor);
 		splx(s);
-		thread_block((void (*)()) 0);
+		thread_block(thread_no_continuation);
 		s = splsched();
 		processor_lock(processor);
 	}
@@ -415,7 +415,7 @@ void processor_doaction(processor_t processor)
 	 */
 	this_thread = current_thread();
 	thread_bind(this_thread, processor);
-	thread_block((void (*)()) 0);
+	thread_block(thread_no_continuation);
 
 	pset = processor->processor_set;
 #if	MACH_HOST
@@ -572,7 +572,7 @@ Restart_pset:
 		thread_deallocate(prev_thread);
 	    thread_bind(this_thread, PROCESSOR_NULL);
 
-	    thread_block((void (*)()) 0);
+	    thread_block(thread_no_continuation);
 	    return;
 	}
 
diff --git a/kern/profile.c b/kern/profile.c
index 55107218..2c9c44bb 100644
--- a/kern/profile.c
+++ b/kern/profile.c
@@ -213,7 +213,7 @@ thread_t th;
 		thread_wakeup((event_t) profile_thread);
 		assert_wait((event_t) &buf_entry->wakeme, TRUE);
 		splx(s);
-		thread_block((void (*)()) 0);
+		thread_block(thread_no_continuation);
 	} else {
 		splx(s);
 		kmem_free(kernel_map, vm_buf_entry, sizeof(struct buf_to_send));
diff --git a/kern/sched_prim.c b/kern/sched_prim.c
index e8f260e3..580ca438 100644
--- a/kern/sched_prim.c
+++ b/kern/sched_prim.c
@@ -454,7 +454,7 @@ void thread_sleep(
 {
 	assert_wait(event, interruptible);	/* assert event */
 	simple_unlock(lock);			/* release the lock */
-	thread_block((void (*)()) 0);		/* block ourselves */
+	thread_block(thread_no_continuation);	/* block ourselves */
 }
 
 /*
@@ -617,7 +617,7 @@ boolean_t thread_invoke(
 	    thread_unlock(new_thread);
 	    thread_wakeup(TH_EV_STATE(new_thread));
 
-	    if (continuation != (void (*)()) 0) {
+	    if (continuation != thread_no_continuation) {
 		(void) spl0();
 		call_continuation(continuation);
 		/*NOTREACHED*/
@@ -630,7 +630,7 @@ boolean_t thread_invoke(
 	 */
 	thread_lock(new_thread);
 	if ((old_thread->stack_privilege != current_stack()) &&
-	    (continuation != (void (*)()) 0))
+	    (continuation != thread_no_continuation))
 	{
 	    switch (new_thread->state & TH_SWAP_STATE) {
 		case TH_SWAPPED:
@@ -915,7 +915,7 @@ void thread_dispatch(
 
 	thread_lock(thread);
 
-	if (thread->swap_func != (void (*)()) 0) {
+	if (thread->swap_func != thread_no_continuation) {
 		assert((thread->state & TH_SWAP_STATE) == 0);
 		thread->state |= TH_SWAPPED;
 		stack_free(thread);
diff --git a/kern/sched_prim.h b/kern/sched_prim.h
index 62698dc2..bb1865cd 100644
--- a/kern/sched_prim.h
+++ b/kern/sched_prim.h
@@ -52,6 +52,8 @@ typedef	void	*event_t;			/* wait event */
 
 typedef	void	(*continuation_t)(void);	/* continuation */
 
+#define thread_no_continuation ((continuation_t) 0) /* no continuation */
+
 /*
  *	Exported interface to sched_prim.c.
  */
diff --git a/kern/task.c b/kern/task.c
index 9a3d8482..e9e6ba24 100644
--- a/kern/task.c
+++ b/kern/task.c
@@ -377,7 +377,7 @@ kern_return_t task_terminate(
                 task_unlock(task);
                 thread_force_terminate(thread);
                 thread_deallocate(thread);
-                thread_block((void (*)()) 0);
+                thread_block(thread_no_continuation);
                 task_lock(task);
         }
         task_unlock(task);
@@ -893,7 +893,7 @@ task_assign(
 		task->assign_active = TRUE;
 		assert_wait((event_t)&task->assign_active, TRUE);
 		task_unlock(task);
-		thread_block((void (*)()) 0);
+		thread_block(thread_no_continuation);
 		task_lock(task);
 	}
 
diff --git a/kern/thread.c b/kern/thread.c
index 865a1cc4..c638075c 100644
--- a/kern/thread.c
+++ b/kern/thread.c
@@ -1348,7 +1348,7 @@ kern_return_t thread_suspend(
 	while (thread->state & TH_UNINT) {
 		assert_wait(TH_EV_STATE(thread), TRUE);
 		thread_unlock(thread);
-		thread_block(NULL);
+		thread_block(thread_no_continuation);
 		thread_lock(thread);
 	}
 	if (thread->user_stop_count++ == 0) {
diff --git a/kern/thread.h b/kern/thread.h
index 0e85d8c4..949d6189 100644
--- a/kern/thread.h
+++ b/kern/thread.h
@@ -100,7 +100,7 @@ struct thread {
 	vm_offset_t	stack_privilege;/* reserved kernel stack */
 
 	/* Swapping information */
-	void		(*swap_func)();	/* start here after swapin */
+	continuation_t	swap_func;	/* start here after swapin */
 
 	/* Blocking information */
 	event_t		wait_event;	/* event we are waiting on */
-- 
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