fs/proc/array.c: change do_task_stat() to use while_each_thread()

Change the remaining next_thread (ab)users to use while_each_thread().

The last user which should be changed is next_tid(), but we can't do this
now.

__exit_signal() and complete_signal() are fine, they actually need
next_thread() logic.

This patch (of 3):

do_task_stat() can use while_each_thread(), no changes in
the compiled code.

Signed-off-by: Oleg Nesterov <[email protected]>
Cc: KOSAKI Motohiro <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Kees Cook <[email protected]>
Reviewed-by: Sameer Nanda <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

fs/proc/array.c

@@ -444,8 +444,7 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
 				min_flt += t->min_flt;
 				maj_flt += t->maj_flt;
 				gtime += task_gtime(t);
-				t = next_thread(t);
-			} while (t != task);
+			} while_each_thread(task, t);
 
 			min_flt += sig->min_flt;
 			maj_flt += sig->maj_flt;