wait_task_zombie: do not use thread_group_cputime()

There is no reason for thread_group_cputime() in wait_task_zombie(), there
must be no other threads.

This call was previously needed to collect the per-cpu data which we do
not have any longer.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Roland McGrath <roland@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Vitaly Mayatskikh <vmayatsk@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 10 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index 826e1dc8168b..94a9992e6fd9 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1191,7 +1191,6 @@ static int wait_task_zombie(struct task_struct *p, int options,
         if (likely(!traced)) {
                 struct signal_struct *psig;
                 struct signal_struct *sig;
-                struct task_cputime cputime;
 
                 /*
                  * The resource counters for the group leader are in its
@@ -1207,23 +1206,20 @@ static int wait_task_zombie(struct task_struct *p, int options,
                  * need to protect the access to parent->signal fields,
                  * as other threads in the parent group can be right
                  * here reaping other children at the same time.
-                 *
-                 * We use thread_group_cputime() to get times for the thread
-                 * group, which consolidates times for all threads in the
-                 * group including the group leader.
                  */
-                thread_group_cputime(p, &cputime);
                 spin_lock_irq(&p->real_parent->sighand->siglock);
                 psig = p->real_parent->signal;
                 sig = p->signal;
                 psig->cutime =
                         cputime_add(psig->cutime,
-                        cputime_add(cputime.utime,
-                                    sig->cutime));
+                        cputime_add(p->utime,
+                        cputime_add(sig->utime,
+                                    sig->cutime)));
                 psig->cstime =
                         cputime_add(psig->cstime,
-                        cputime_add(cputime.stime,
-                                    sig->cstime));
+                        cputime_add(p->stime,
+                        cputime_add(sig->stime,
+                                    sig->cstime)));
                 psig->cgtime =
                         cputime_add(psig->cgtime,
                         cputime_add(p->gtime,