sched: Update rq clock before migrating tasks out of dying CPU

Because the sched_class::put_prev_task() callback of rt and fair
classes are referring to the rq clock to update their runtime
statistics. There is a missing rq clock update from the CPU
hotplug notifier's entry point of the scheduler.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Turner <pjt@google.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1365724262-20142-2-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 79e48e6a9385..7bf0418dc60f 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4378,6 +4378,13 @@ static void migrate_tasks(unsigned int dead_cpu)
          */
         rq->stop = NULL;
 
+        /*
+         * put_prev_task() and pick_next_task() sched
+         * class method both need to have an up-to-date
+         * value of rq->clock[_task]
+         */
+        update_rq_clock(rq);
+
         for ( ; ; ) {
                 /*
                  * There's this thread running, bail when that's the only