Added different paths of exiting for pager and its children.

Created a task_dead list on pager for children to move to when
they exit.

conts/test/main.c

@@ -55,6 +55,7 @@ int main(void)
 
 	/* Now quit to demo self-paging quit */
 	l4_exit(0);
+
 	/* Now quit by null pointer */
 	//	*((int *)0) = 5;
 

include/l4/generic/resource.h

@@ -10,6 +10,7 @@
 /* Number of containers defined at compile-time */
 #include <l4/generic/capability.h>
 #include <l4/lib/list.h>
+#include <l4/lib/mutex.h>
 #include <l4/lib/idpool.h>
 #include INC_SUBARCH(mm.h)
 
@@ -43,7 +44,7 @@ container_head_init(struct container_head *chead)
 /* Hash table for all existing tasks */
 struct ktcb_list {
 	struct link list;
-	struct spinlock list_lock;
+	struct mutex list_lock;
 	int count;
 };
 

include/l4/generic/tcb.h

@@ -80,6 +80,7 @@ struct ktcb {
 	enum task_state state;
 
 	struct link task_list; /* Global task list. */
+	struct ktcb_list task_dead; /* List of dead children */
 
 	/* UTCB related, see utcb.txt in docs */
 	unsigned long utcb_address;	/* Virtual ref to task's utcb area */

src/api/thread.c

@@ -183,23 +183,32 @@ void thread_destroy_current(void)
 {
 	struct ktcb *task, *n;
 
-	/* Suspend all threads under control of this pager */
-	spin_lock(&curcont->ktcb_list.list_lock);
+	/* Signal death to all threads under control of this pager */
+	mutex_lock(&curcont->ktcb_list.list_lock);
 	list_foreach_removable_struct(task, n,
 				      &curcont->ktcb_list.list,
 				      task_list) {
 		if (task->tid == current->tid ||
 		    task->pagerid != current->tid)
 			continue;
-		spin_unlock(&curcont->ktcb_list.list_lock);
+		mutex_unlock(&curcont->ktcb_list.list_lock);
+
+		/* Here we wait for each to die */
 		thread_suspend(task, TASK_EXITING);
-		spin_lock(&curcont->ktcb_list.list_lock);
+		mutex_lock(&curcont->ktcb_list.list_lock);
 	}
-	spin_unlock(&curcont->ktcb_list.list_lock);
+	mutex_unlock(&curcont->ktcb_list.list_lock);
 
-	/* Indicate we want to become zombie on suspend */
-	current->flags |= TASK_EXITING;
+	/* Destroy all children */
+	mutex_lock(&current->task_dead.list_lock);
+	list_foreach_removable_struct(task, n,
+				      &current->task_dead.list,
+				      task_list) {
+		tcb_delete(task);
+	}
+	mutex_unlock(&current->task_dead.list_lock);
 
+	/* Destroy self */
 	sched_die_sync();
 }
 

src/arch/arm/exception.c

@@ -123,8 +123,7 @@ void fault_ipc_to_pager(u32 faulty_pc, u32 fsr, u32 far)
 		       "returned error (%d). Suspend and exiting thread.\n",
 		       current->tid, err);
 		BUG_ON(current->nlocks);
-		current->flags |= TASK_EXITING;
-		sched_suspend_sync();
+		sched_die_sync();
 	}
 }
 

src/generic/scheduler.c

@@ -255,7 +255,12 @@ void tcb_delete_schedule(void)
 }
 #endif
 
-void sched_die_sync(void)
+
+/*
+ * A self-paging thread deletes itself,
+ * schedules and disappears from the system.
+ */
+void sched_die_pager(void)
 {
 	/* Remove from its list, callers get -ESRCH */
 	tcb_remove(current);
@@ -290,6 +295,80 @@ void sched_die_sync(void)
 	BUG();
 }
 
+/*
+ * A paged-thread leaves the system and waits on
+ * its pager's task_dead queue.
+ */
+void sched_die_child(void)
+{
+	/*
+	 * Find pager, he _must_ be there because he never
+	 * quits before quitting us
+	 */
+	struct ktcb *pager = tcb_find(current->pagerid);
+
+	/* Lock its task_dead queue */
+	mutex_lock(&pager->task_dead.list_lock);
+
+	/* Remove from container task list,
+	 * callers get -ESRCH */
+	tcb_remove(current);
+
+	/*
+	 * If the pager searches for us to destroy,
+	 * he won't find us but he will block on the
+	 * task_dead mutex when searching whether
+	 * we died already.
+	 */
+
+	/*
+	 * If there are any sleepers on any of the task's
+	 * waitqueues, we need to wake those tasks up.
+	 */
+	wake_up_all(&current->wqh_send, 0);
+	wake_up_all(&current->wqh_recv, 0);
+
+	/*
+	 * Add self to pager's dead tasks list,
+	 * to be deleted by pager
+	 */
+	ktcb_list_add(current, &pager->task_dead);
+
+	/* Now quit the scheduler */
+	preempt_disable();
+	sched_rq_remove_task(current);
+	current->state = TASK_INACTIVE;
+	current->flags &= ~TASK_SUSPENDING;
+	scheduler.prio_total -= current->priority;
+	BUG_ON(scheduler.prio_total < 0);
+	preempt_enable();
+
+	/*
+	 * Unlock task_dead queue,
+	 * pager can safely delete us
+	 */
+	mutex_unlock(&pager->task_dead.list_lock);
+	BUG();
+}
+
+void sched_die_sync(void)
+{
+	if (current->tid == current->pagerid)
+		sched_die_pager();
+	else
+		sched_die_child();
+}
+
+/*
+ * TODO:
+ * Instead of sched_suspend_sync()
+ * call sched_die_sync() on killer suspends:
+ * (e.g. if also kill flag set, call sched_die_sync instead)
+ * and handle dying on its own and dying over a pager
+ * in there. (e.g. put yourself in a task_dead queue, take
+ * care of pager calling destroy on you, calling wait on you etc.)
+ */
+
 /*
  * NOTE: Could do these as sched_prepare_suspend()
  * + schedule() or need_resched = 1
@@ -304,9 +383,6 @@ void sched_suspend_sync(void)
 	BUG_ON(scheduler.prio_total < 0);
 	preempt_enable();
 
-	if (current->flags & TASK_EXITING)
-		task_make_zombie(current);
-
 	/*
 	 * Async wake up any waiting pagers
 	 *

src/generic/tcb.c

@@ -20,7 +20,7 @@
 void init_ktcb_list(struct ktcb_list *ktcb_list)
 {
 	memset(ktcb_list, 0, sizeof(*ktcb_list));
-	spin_lock_init(&ktcb_list->list_lock);
+	mutex_init(&ktcb_list->list_lock);
 	link_init(&ktcb_list->list);
 }
 
@@ -30,6 +30,8 @@ void tcb_init(struct ktcb *new)
 	link_init(&new->task_list);
 	mutex_init(&new->thread_control_lock);
 
+	init_ktcb_list(&new->task_dead);
+
 	cap_list_init(&new->cap_list);
 
 	/* Initialise task's scheduling state and parameters. */
@@ -101,14 +103,14 @@ struct ktcb *tcb_find_by_space(l4id_t spid)
 {
 	struct ktcb *task;
 
-	spin_lock(&curcont->ktcb_list.list_lock);
+	mutex_lock(&curcont->ktcb_list.list_lock);
 	list_foreach_struct(task, &curcont->ktcb_list.list, task_list) {
 		if (task->space->spid == spid) {
-			spin_unlock(&curcont->ktcb_list.list_lock);
+			mutex_unlock(&curcont->ktcb_list.list_lock);
 			return task;
 		}
 	}
-	spin_unlock(&curcont->ktcb_list.list_lock);
+	mutex_unlock(&curcont->ktcb_list.list_lock);
 	return 0;
 }
 
@@ -119,44 +121,44 @@ struct ktcb *tcb_find(l4id_t tid)
 	if (current->tid == tid)
 		return current;
 
-	spin_lock(&curcont->ktcb_list.list_lock);
+	mutex_lock(&curcont->ktcb_list.list_lock);
 	list_foreach_struct(task, &curcont->ktcb_list.list, task_list) {
 		if (task->tid == tid) {
-			spin_unlock(&curcont->ktcb_list.list_lock);
+			mutex_unlock(&curcont->ktcb_list.list_lock);
 			return task;
 		}
 	}
-	spin_unlock(&curcont->ktcb_list.list_lock);
+	mutex_unlock(&curcont->ktcb_list.list_lock);
 	return 0;
 }
 
 void ktcb_list_add(struct ktcb *new, struct ktcb_list *ktcb_list)
 {
-	spin_lock(&ktcb_list->list_lock);
+	mutex_lock(&ktcb_list->list_lock);
 	BUG_ON(!list_empty(&new->task_list));
 	BUG_ON(!++ktcb_list->count);
 	list_insert(&new->task_list, &ktcb_list->list);
-	spin_unlock(&ktcb_list->list_lock);
+	mutex_unlock(&ktcb_list->list_lock);
 }
 
 void tcb_add(struct ktcb *new)
 {
 	struct container *c = new->container;
 
-	spin_lock(&c->ktcb_list.list_lock);
+	mutex_lock(&c->ktcb_list.list_lock);
 	BUG_ON(!list_empty(&new->task_list));
 	BUG_ON(!++c->ktcb_list.count);
 	list_insert(&new->task_list, &c->ktcb_list.list);
-	spin_unlock(&c->ktcb_list.list_lock);
+	mutex_unlock(&c->ktcb_list.list_lock);
 }
 
 void tcb_remove(struct ktcb *new)
 {
-	spin_lock(&curcont->ktcb_list.list_lock);
+	mutex_lock(&curcont->ktcb_list.list_lock);
 	BUG_ON(list_empty(&new->task_list));
 	BUG_ON(--curcont->ktcb_list.count < 0);
 	list_remove_init(&new->task_list);
-	spin_unlock(&curcont->ktcb_list.list_lock);
+	mutex_unlock(&curcont->ktcb_list.list_lock);
 }
 
 /* Offsets for ktcb fields that are accessed from assembler */

src/glue/arm/systable.c

@@ -169,7 +169,10 @@ int syscall(syscall_context_t *regs, unsigned long swi_addr)
 
 	if (current->flags & TASK_SUSPENDING) {
 		BUG_ON(current->nlocks);
-		sched_suspend_sync();
+		if (current->flags & TASK_EXITING)
+			sched_die_sync();
+		else
+			sched_suspend_sync();
 	}
 
 	return ret;