kernel: add a kernel_wait helper

Add a helper that waits for a pid and stores the status in the passed in
kernel pointer.  Use it to fix the usage of kernel_wait4 in
call_usermodehelper_exec_sync that only happens to work due to the
implicit set_fs(KERNEL_DS) for kernel threads.

Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Reviewed-by: Andrew Morton <[email protected]>
Acked-by: "Eric W. Biederman" <[email protected]>
Cc: Luis Chamberlain <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h
index ae3060f0b0c9..a98965007eef 100644
--- a/include/linux/sched/task.h
+++ b/include/linux/sched/task.h
@@ -88,6 +88,7 @@ struct task_struct *fork_idle(int);
 struct mm_struct *copy_init_mm(void);
 extern pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
 extern long kernel_wait4(pid_t, int __user *, int, struct rusage *);
+int kernel_wait(pid_t pid, int *stat);
 
 extern void free_task(struct task_struct *tsk);