wait: completely ignore the EXIT_DEAD tasks

Now that EXIT_DEAD is the terminal state it doesn't make sense to call
eligible_child() or security_task_wait() if the task is really dead.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Tested-by: Michal Schmidt <mschmidt@redhat.com>
Cc: Jan Kratochvil <jan.kratochvil@redhat.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Lennart Poettering <lpoetter@redhat.com>
Cc: Roland McGrath <roland@hack.frob.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 5 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index 4773ed990907..33cf8dba0a61 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1329,7 +1329,12 @@ static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
 static int wait_consider_task(struct wait_opts *wo, int ptrace,
                                 struct task_struct *p)
 {
-        int ret = eligible_child(wo, p);
+        int ret;
+
+        if (unlikely(p->exit_state == EXIT_DEAD))
+                return 0;
+
+        ret = eligible_child(wo, p);
         if (!ret)
                 return ret;
 
@@ -1347,10 +1352,6 @@ static int wait_consider_task(struct wait_opts *wo, int ptrace,
                 return 0;
         }
 
-        /* dead body doesn't have much to contribute */
-        if (unlikely(p->exit_state == EXIT_DEAD))
-                return 0;
-
         if (unlikely(p->exit_state == EXIT_TRACE)) {
                 /*
                  * ptrace == 0 means we are the natural parent. In this case