Merge branch 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer updates from Ingo Molnar:
 "The main purpose is to fix a full dynticks bug related to
  virtualization, where steal time accounting appears to be zero in
  /proc/stat even after a few seconds of competing guests running busy
  loops in a same host CPU.  It's not a regression though as it was
  there since the beginning.

  The other commits are preparatory work to fix the bug and various
  cleanups"

* 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  arch: Remove stub cputime.h headers
  sched: Remove needless round trip nsecs <-> tick conversion of steal time
  cputime: Fix jiffies based cputime assumption on steal accounting
  cputime: Bring cputime -> nsecs conversion
  cputime: Default implementation of nsecs -> cputime conversion
  cputime: Fix nsecs_to_cputime() return type cast

1 files changed, 11 insertions, 5 deletions

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 58624a65f124..a95097cb4591 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -258,16 +258,22 @@ static __always_inline bool steal_account_process_tick(void)
 {
 #ifdef CONFIG_PARAVIRT
 	if (static_key_false(&paravirt_steal_enabled)) {
-		u64 steal, st = 0;
+		u64 steal;
+		cputime_t steal_ct;
 
 		steal = paravirt_steal_clock(smp_processor_id());
 		steal -= this_rq()->prev_steal_time;
 
-		st = steal_ticks(steal);
-		this_rq()->prev_steal_time += st * TICK_NSEC;
+		/*
+		 * cputime_t may be less precise than nsecs (eg: if it's
+		 * based on jiffies). Lets cast the result to cputime
+		 * granularity and account the rest on the next rounds.
+		 */
+		steal_ct = nsecs_to_cputime(steal);
+		this_rq()->prev_steal_time += cputime_to_nsecs(steal_ct);
 
-		account_steal_time(st);
-		return st;
+		account_steal_time(steal_ct);
+		return steal_ct;
 	}
 #endif
 	return false;