Fix x86 "switch_to()" to properly set the previous task information,

which is needed to keep track of process usage counts correctly and
efficiently.

2 files changed, 9 insertions, 2 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index 6f137beea865..203fe93429de 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -74,6 +74,9 @@ int nr_processes(void)
 
 void __put_task_struct(struct task_struct *tsk)
 {
+	WARN_ON(!(tsk->state & (TASK_DEAD | TASK_ZOMBIE)));
+	WARN_ON(atomic_read(&tsk->usage));
+
 	if (tsk != current) {
 		free_thread_info(tsk->thread_info);
 		kmem_cache_free(task_struct_cachep,tsk);
@@ -217,7 +220,9 @@ static struct task_struct *dup_task_struct(struct task_struct *orig)
 	*tsk = *orig;
 	tsk->thread_info = ti;
 	ti->task = tsk;
-	atomic_set(&tsk->usage,1);
+
+	/* One for us, one for whoever does the "release_task()" (usually parent) */
+	atomic_set(&tsk->usage,2);
 	return tsk;
 }
 
diff --git a/kernel/sched.c b/kernel/sched.c
index fe4139562dca..ad1ac7be565a 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -581,6 +581,8 @@ static inline void finish_task_switch(task_t *prev)
 	finish_arch_switch(rq, prev);
 	if (mm)
 		mmdrop(mm);
+	if (prev->state & (TASK_DEAD | TASK_ZOMBIE))
+		put_task_struct(prev);
 }
 
 /**
@@ -1185,7 +1187,7 @@ asmlinkage void schedule(void)
 	 * schedule() atomically, we ignore that path for now.
 	 * Otherwise, whine if we are scheduling when we should not be.
 	 */
-	if (likely(current->state != TASK_ZOMBIE)) {
+	if (likely(!(current->state & (TASK_DEAD | TASK_ZOMBIE)))) {
 		if (unlikely(in_atomic())) {
 			printk(KERN_ERR "bad: scheduling while atomic!\n");
 			dump_stack();