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

[mirror_ubuntu-zesty-kernel.git] / fs / proc / base.c

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 03c8d747be48be2a14e93fed94355d42c5d7bd52..be8e17cabfc75c53ad2e3ad6d6ec3c46d63afc83 100644 (file)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -3106,20 +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 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: