proc: change first_tid() to use while_each_thread() rather than next_thread()

Rerwrite the main loop to use while_each_thread() instead of
next_thread().  We are going to fix or replace while_each_thread(),
next_thread() should be avoided whenever possible.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Sameer Nanda <snanda@chromium.org>
Cc: Sergey Dyasly <dserrg@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 10 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index f223a56e613c..be8e17cabfc7 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -3106,23 +3106,23 @@ static struct task_struct *first_tid(struct task_struct *leader,
         }
 
         /* If nr exceeds the number of threads there is nothing todo */
-        pos = NULL;
         if (nr && nr >= get_nr_threads(leader))
-                goto out;
+                goto fail;
         /* It could be unhashed before we take rcu lock */
         if (!pid_alive(leader))
-                goto out;
+                goto fail;
 
         /* If we haven't found our starting place yet start
          * with the leader and walk nr threads forward.
          */
-        for (pos = leader; nr > 0; --nr) {
-                pos = next_thread(pos);
-                if (pos == leader) {
-                        pos = NULL;
-                        goto out;
-                }
-        }
+        pos = leader;
+        do {
+                if (nr-- <= 0)
+                        goto found;
+        } while_each_thread(leader, pos);
+fail:
+        pos = NULL;
+        goto out;
 found:
         get_task_struct(pos);
 out: