X-Git-Url: http://drtracing.org/?a=blobdiff_plain;f=kernel%2Fsched%2Fstats.h;h=5aef494fc8b42471006a48c516737b93aa086fb7;hb=21884a83b2192a00885d7244a1dda32debd2fbc7;hp=17d7065c38721a3431e011642e8d6e634d10a40d;hpb=da67db4e55b45690cd283cdbdfa92d3252191108;p=deliverable%2Flinux.git

diff --git a/kernel/sched/stats.h b/kernel/sched/stats.h
index 17d7065c3872..5aef494fc8b4 100644
--- a/kernel/sched/stats.h
+++ b/kernel/sched/stats.h
@@ -161,6 +161,39 @@ sched_info_switch(struct task_struct *prev, struct task_struct *next)
  * on CONFIG_SCHEDSTATS.
  */
 
+/**
+ * cputimer_running - return true if cputimer is running
+ *
+ * @tsk:	Pointer to target task.
+ */
+static inline bool cputimer_running(struct task_struct *tsk)
+
+{
+	struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
+
+	if (!cputimer->running)
+		return false;
+
+	/*
+	 * After we flush the task's sum_exec_runtime to sig->sum_sched_runtime
+	 * in __exit_signal(), we won't account to the signal struct further
+	 * cputime consumed by that task, even though the task can still be
+	 * ticking after __exit_signal().
+	 *
+	 * In order to keep a consistent behaviour between thread group cputime
+	 * and thread group cputimer accounting, lets also ignore the cputime
+	 * elapsing after __exit_signal() in any thread group timer running.
+	 *
+	 * This makes sure that POSIX CPU clocks and timers are synchronized, so
+	 * that a POSIX CPU timer won't expire while the corresponding POSIX CPU
+	 * clock delta is behind the expiring timer value.
+	 */
+	if (unlikely(!tsk->sighand))
+		return false;
+
+	return true;
+}
+
 /**
  * account_group_user_time - Maintain utime for a thread group.
  *
@@ -176,7 +209,7 @@ static inline void account_group_user_time(struct task_struct *tsk,
 {
 	struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
 
-	if (!cputimer->running)
+	if (!cputimer_running(tsk))
 		return;
 
 	raw_spin_lock(&cputimer->lock);
@@ -199,7 +232,7 @@ static inline void account_group_system_time(struct task_struct *tsk,
 {
 	struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
 
-	if (!cputimer->running)
+	if (!cputimer_running(tsk))
 		return;
 
 	raw_spin_lock(&cputimer->lock);
@@ -222,7 +255,7 @@ static inline void account_group_exec_runtime(struct task_struct *tsk,
 {
 	struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
 
-	if (!cputimer->running)
+	if (!cputimer_running(tsk))
 		return;
 
 	raw_spin_lock(&cputimer->lock);