posix_cpu_timers: consolidate timer list cleanups

Cleaning up the posix cpu timers on task exit shares some common code
among timer list types, most notably the list traversal and expiry time
update.

Unify this in a common helper.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Cc: Olivier Langlois <olivier@trillion01.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index c3c4ea1..b1450ce 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -399,6 +399,21 @@
 	return ret;
 }
 
+static void cleanup_timers_list(struct list_head *head,
+				unsigned long long curr)
+{
+	struct cpu_timer_list *timer, *next;
+
+	list_for_each_entry_safe(timer, next, head, entry) {
+		list_del_init(&timer->entry);
+		if (timer->expires < curr) {
+			timer->expires = 0;
+		} else {
+			timer->expires -= curr;
+		}
+	}
+}
+
 /*
  * Clean out CPU timers still ticking when a thread exited.  The task
  * pointer is cleared, and the expiry time is replaced with the residual
@@ -409,37 +424,12 @@
 			   cputime_t utime, cputime_t stime,
 			   unsigned long long sum_exec_runtime)
 {
-	struct cpu_timer_list *timer, *next;
+
 	cputime_t ptime = utime + stime;
 
-	list_for_each_entry_safe(timer, next, head, entry) {
-		list_del_init(&timer->entry);
-		if (timer->expires < cputime_to_expires(ptime)) {
-			timer->expires = 0;
-		} else {
-			timer->expires -= cputime_to_expires(ptime);
-		}
-	}
-
-	++head;
-	list_for_each_entry_safe(timer, next, head, entry) {
-		list_del_init(&timer->entry);
-		if (timer->expires < cputime_to_expires(utime)) {
-			timer->expires = 0;
-		} else {
-			timer->expires -= cputime_to_expires(utime);
-		}
-	}
-
-	++head;
-	list_for_each_entry_safe(timer, next, head, entry) {
-		list_del_init(&timer->entry);
-		if (timer->expires < sum_exec_runtime) {
-			timer->expires = 0;
-		} else {
-			timer->expires -= sum_exec_runtime;
-		}
-	}
+	cleanup_timers_list(head, cputime_to_expires(ptime));
+	cleanup_timers_list(++head, cputime_to_expires(utime));
+	cleanup_timers_list(++head, sum_exec_runtime);
 }
 
 /*