From: KOSAKI Motohiro <kosaki.motoh...@jp.fujitsu.com>
When tsk->signal->cputimer->running is 1, signal->cputimer and
tsk->sum_sched_runtime increase at the same pace because update_curr()
increases both accounting.
However, there is one exception. When thread exiting, __exit_signal() turns
over task's sum_shced_runtime to sig->sum_sched_runtime, but it doesn't stop
signal->cputimer accounting.
This inconsistency makes POSIX timer wake up too early. This patch fixes it.
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Frederic Weisbecker <fweis...@gmail.com>
Cc: Ingo Molnar <mi...@kernel.org>
Acked-by: Peter Zijlstra <pet...@infradead.org>
Signed-off-by: Olivier Langlois <oliv...@trillion01.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motoh...@jp.fujitsu.com>
---
kernel/sched/stats.h | 7 +++++++
1 files changed, 7 insertions(+), 0 deletions(-)
diff --git a/kernel/sched/stats.h b/kernel/sched/stats.h
index 2ef90a5..5a0cfc4 100644
--- a/kernel/sched/stats.h
+++ b/kernel/sched/stats.h
@@ -225,6 +225,13 @@ static inline void account_group_exec_runtime(struct
task_struct *tsk,
if (!cputimer->running)
return;
+ /*
+ * After turning over se.sum_exec_runtime to sig->sum_sched_runtime
+ * in __exit_signal(), we must not account exec_runtime for consistency.
+ */
+ if (unlikely(!tsk->sighand))
+ return;
+
raw_spin_lock(&cputimer->lock);
cputimer->cputime.sum_exec_runtime += ns;
raw_spin_unlock(&cputimer->lock);
--
1.7.1
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