[PATCH] remove __put_task_struct_cb export again

The patch '[PATCH] RCU signal handling' [1] added an export for
__put_task_struct_cb, a put_task_struct helper newly introduced in that
patch. But the put_task_struct couldn't be used modular previously as
__put_task_struct wasn't exported. There are not callers of it in modular
code, and it shouldn't be exported because we don't want drivers to hold
references to task_structs.

This patch removes the export and folds __put_task_struct into
__put_task_struct_cb as there's no other caller.

[1] http://www2.kernel.org/git/gitweb.cgi?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=e56d090310d7625ecb43a1eeebd479f04affb48b

Signed-off-by: Christoph Hellwig <[e-mail]>
Acked-by: Paul E. McKenney <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

include/linux/sched.h

···
 }
 
 extern void free_task(struct task_struct *tsk);
-extern void __put_task_struct(struct task_struct *tsk);
 #define get_task_struct(tsk) do { atomic_inc(&(tsk)->usage); } while(0)
 
 extern void __put_task_struct_cb(struct rcu_head *rhp);

kernel/fork.c

···
 }
 EXPORT_SYMBOL(free_task);
 
-void __put_task_struct(struct task_struct *tsk)
+void __put_task_struct_cb(struct rcu_head *rhp)
 {
+	struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
+
 	WARN_ON(!(tsk->exit_state & (EXIT_DEAD | EXIT_ZOMBIE)));
 	WARN_ON(atomic_read(&tsk->usage));
 	WARN_ON(tsk == current);

kernel/sched.c

···
 #define task_hot(p, now, sd) ((long long) ((now) - (p)->last_ran)	\
 				< (long long) (sd)->cache_hot_time)
 
-void __put_task_struct_cb(struct rcu_head *rhp)
-{
-	__put_task_struct(container_of(rhp, struct task_struct, rcu));
-}
-
-EXPORT_SYMBOL_GPL(__put_task_struct_cb);
-
 /*
  * These are the runqueue data structures:
  */