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

28 files changed, 48 insertions, 62 deletions

diff --git a/arch/alpha/include/asm/Kbuild b/arch/alpha/include/asm/Kbuild
index 7736f426ff3b..96e54bed5088 100644
--- a/arch/alpha/include/asm/Kbuild
+++ b/arch/alpha/include/asm/Kbuild
@@ -1,6 +1,7 @@
 
 
 generic-y += clkdev.h
+generic-y += cputime.h
 generic-y += exec.h
 generic-y += hash.h
 generic-y += mcs_spinlock.h
diff --git a/arch/alpha/include/asm/cputime.h b/arch/alpha/include/asm/cputime.h
deleted file mode 100644
index 19577fd93230..000000000000
--- a/arch/alpha/include/asm/cputime.h
+++ /dev/null
@@ -1,6 +0,0 @@
-#ifndef __ALPHA_CPUTIME_H
-#define __ALPHA_CPUTIME_H
-
-#include <asm-generic/cputime.h>
-
-#endif /* __ALPHA_CPUTIME_H */
diff --git a/arch/cris/include/asm/Kbuild b/arch/cris/include/asm/Kbuild
index 056027f38351..afff5105909d 100644
--- a/arch/cris/include/asm/Kbuild
+++ b/arch/cris/include/asm/Kbuild
@@ -5,6 +5,7 @@ header-y += arch-v32/
 
 generic-y += barrier.h
 generic-y += clkdev.h
+generic-y += cputime.h
 generic-y += exec.h
 generic-y += hash.h
 generic-y += kvm_para.h
diff --git a/arch/cris/include/asm/cputime.h b/arch/cris/include/asm/cputime.h
deleted file mode 100644
index 4446a65656fa..000000000000
--- a/arch/cris/include/asm/cputime.h
+++ /dev/null
@@ -1,6 +0,0 @@
-#ifndef __CRIS_CPUTIME_H
-#define __CRIS_CPUTIME_H
-
-#include <asm-generic/cputime.h>
-
-#endif /* __CRIS_CPUTIME_H */
diff --git a/arch/frv/include/asm/Kbuild b/arch/frv/include/asm/Kbuild
index babb9338ebf8..87b95eb8aee5 100644
--- a/arch/frv/include/asm/Kbuild
+++ b/arch/frv/include/asm/Kbuild
@@ -1,5 +1,6 @@
 
 generic-y += clkdev.h
+generic-y += cputime.h
 generic-y += exec.h
 generic-y += hash.h
 generic-y += mcs_spinlock.h
diff --git a/arch/frv/include/asm/cputime.h b/arch/frv/include/asm/cputime.h
deleted file mode 100644
index f6c373ad2b80..000000000000
--- a/arch/frv/include/asm/cputime.h
+++ /dev/null
@@ -1,6 +0,0 @@
-#ifndef _ASM_CPUTIME_H
-#define _ASM_CPUTIME_H
-
-#include <asm-generic/cputime.h>
-
-#endif /* _ASM_CPUTIME_H */
diff --git a/arch/m32r/include/asm/Kbuild b/arch/m32r/include/asm/Kbuild
index 5825a35b2c56..67779a74b62d 100644
--- a/arch/m32r/include/asm/Kbuild
+++ b/arch/m32r/include/asm/Kbuild
@@ -1,5 +1,6 @@
 
 generic-y += clkdev.h
+generic-y += cputime.h
 generic-y += exec.h
 generic-y += hash.h
 generic-y += mcs_spinlock.h
diff --git a/arch/m32r/include/asm/cputime.h b/arch/m32r/include/asm/cputime.h
deleted file mode 100644
index 0a47550df2b7..000000000000
--- a/arch/m32r/include/asm/cputime.h
+++ /dev/null
@@ -1,6 +0,0 @@
-#ifndef __M32R_CPUTIME_H
-#define __M32R_CPUTIME_H
-
-#include <asm-generic/cputime.h>
-
-#endif /* __M32R_CPUTIME_H */
diff --git a/arch/microblaze/include/asm/Kbuild b/arch/microblaze/include/asm/Kbuild
index 1f590ab8f323..c98ed95c0541 100644
--- a/arch/microblaze/include/asm/Kbuild
+++ b/arch/microblaze/include/asm/Kbuild
@@ -1,6 +1,7 @@
 
 generic-y += barrier.h
 generic-y += clkdev.h
+generic-y += cputime.h
 generic-y += exec.h
 generic-y += hash.h
 generic-y += mcs_spinlock.h
diff --git a/arch/microblaze/include/asm/cputime.h b/arch/microblaze/include/asm/cputime.h
deleted file mode 100644
index 6d68ad7e0ea3..000000000000
--- a/arch/microblaze/include/asm/cputime.h
+++ /dev/null
@@ -1 +0,0 @@
-#include <asm-generic/cputime.h>
diff --git a/arch/mn10300/include/asm/Kbuild b/arch/mn10300/include/asm/Kbuild
index cbc6b9bf45da..654d5ba6e310 100644
--- a/arch/mn10300/include/asm/Kbuild
+++ b/arch/mn10300/include/asm/Kbuild
@@ -1,6 +1,7 @@
 
 generic-y += barrier.h
 generic-y += clkdev.h
+generic-y += cputime.h
 generic-y += exec.h
 generic-y += hash.h
 generic-y += mcs_spinlock.h
diff --git a/arch/mn10300/include/asm/cputime.h b/arch/mn10300/include/asm/cputime.h
deleted file mode 100644
index 6d68ad7e0ea3..000000000000
--- a/arch/mn10300/include/asm/cputime.h
+++ /dev/null
@@ -1 +0,0 @@
-#include <asm-generic/cputime.h>
diff --git a/arch/score/include/asm/Kbuild b/arch/score/include/asm/Kbuild
index 4630cf217b5b..2f947aba4bd4 100644
--- a/arch/score/include/asm/Kbuild
+++ b/arch/score/include/asm/Kbuild
@@ -4,6 +4,7 @@ header-y +=
 
 generic-y += barrier.h
 generic-y += clkdev.h
+generic-y += cputime.h
 generic-y += hash.h
 generic-y += mcs_spinlock.h
 generic-y += preempt.h
diff --git a/arch/score/include/asm/cputime.h b/arch/score/include/asm/cputime.h
deleted file mode 100644
index 1fced99f0d67..000000000000
--- a/arch/score/include/asm/cputime.h
+++ /dev/null
@@ -1,6 +0,0 @@
-#ifndef _ASM_SCORE_CPUTIME_H
-#define _ASM_SCORE_CPUTIME_H
-
-#include <asm-generic/cputime.h>
-
-#endif /* _ASM_SCORE_CPUTIME_H */
diff --git a/arch/x86/include/asm/Kbuild b/arch/x86/include/asm/Kbuild
index a8fee078b92f..4acddc43ee0c 100644
--- a/arch/x86/include/asm/Kbuild
+++ b/arch/x86/include/asm/Kbuild
@@ -5,4 +5,5 @@ genhdr-y += unistd_64.h
 genhdr-y += unistd_x32.h
 
 generic-y += clkdev.h
+generic-y += cputime.h
 generic-y += mcs_spinlock.h
diff --git a/arch/x86/include/asm/cputime.h b/arch/x86/include/asm/cputime.h
deleted file mode 100644
index 6d68ad7e0ea3..000000000000
--- a/arch/x86/include/asm/cputime.h
+++ /dev/null
@@ -1 +0,0 @@
-#include <asm-generic/cputime.h>
diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
index 5793e1447fb1..79911a27a48a 100644
--- a/drivers/cpufreq/cpufreq_stats.c
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -13,7 +13,7 @@
 #include <linux/cpufreq.h>
 #include <linux/module.h>
 #include <linux/slab.h>
-#include <asm/cputime.h>
+#include <linux/cputime.h>
 
 static spinlock_t cpufreq_stats_lock;
 
diff --git a/drivers/s390/cio/cio.c b/drivers/s390/cio/cio.c
index 97c48b38d67d..d691e6a13aae 100644
--- a/drivers/s390/cio/cio.c
+++ b/drivers/s390/cio/cio.c
@@ -28,7 +28,7 @@
 #include <asm/chpid.h>
 #include <asm/airq.h>
 #include <asm/isc.h>
-#include <asm/cputime.h>
+#include <linux/cputime.h>
 #include <asm/fcx.h>
 #include <asm/nmi.h>
 #include <asm/crw.h>
diff --git a/fs/proc/stat.c b/fs/proc/stat.c
index 6f599c62f0cc..9d231e9e5f0e 100644
--- a/fs/proc/stat.c
+++ b/fs/proc/stat.c
@@ -9,7 +9,7 @@
 #include <linux/slab.h>
 #include <linux/time.h>
 #include <linux/irqnr.h>
-#include <asm/cputime.h>
+#include <linux/cputime.h>
 #include <linux/tick.h>
 
 #ifndef arch_irq_stat_cpu
diff --git a/fs/proc/uptime.c b/fs/proc/uptime.c
index 7141b8d0ca9e..33de567c25af 100644
--- a/fs/proc/uptime.c
+++ b/fs/proc/uptime.c
@@ -5,7 +5,7 @@
 #include <linux/seq_file.h>
 #include <linux/time.h>
 #include <linux/kernel_stat.h>
-#include <asm/cputime.h>
+#include <linux/cputime.h>
 
 static int uptime_proc_show(struct seq_file *m, void *v)
 {
diff --git a/include/asm-generic/cputime_jiffies.h b/include/asm-generic/cputime_jiffies.h
index 272ecba9f588..d5cb78f53986 100644
--- a/include/asm-generic/cputime_jiffies.h
+++ b/include/asm-generic/cputime_jiffies.h
@@ -15,8 +15,10 @@ typedef u64 __nocast cputime64_t;
 
 
 /*
- * Convert nanoseconds to cputime
+ * Convert nanoseconds <-> cputime
  */
+#define cputime_to_nsecs(__ct)          \
+        jiffies_to_nsecs(cputime_to_jiffies(__ct))
 #define nsecs_to_cputime64(__nsec)      \
         jiffies64_to_cputime64(nsecs_to_jiffies64(__nsec))
 #define nsecs_to_cputime(__nsec)        \
diff --git a/include/asm-generic/cputime_nsecs.h b/include/asm-generic/cputime_nsecs.h
index 2c9e62c2bfd0..4e817606c549 100644
--- a/include/asm-generic/cputime_nsecs.h
+++ b/include/asm-generic/cputime_nsecs.h
@@ -44,7 +44,10 @@ typedef u64 __nocast cputime64_t;
 /*
  * Convert cputime <-> nanoseconds
  */
-#define nsecs_to_cputime(__nsecs)       ((__force u64)(__nsecs))
+#define cputime_to_nsecs(__ct)          \
+        (__force u64)(__ct)
+#define nsecs_to_cputime(__nsecs)       \
+        (__force cputime_t)(__nsecs)
 
 
 /*
diff --git a/include/linux/cputime.h b/include/linux/cputime.h
new file mode 100644
index 000000000000..f2eb2ee535ca
--- /dev/null
+++ b/include/linux/cputime.h
@@ -0,0 +1,16 @@
+#ifndef __LINUX_CPUTIME_H
+#define __LINUX_CPUTIME_H
+
+#include <asm/cputime.h>
+
+#ifndef cputime_to_nsecs
+# define cputime_to_nsecs(__ct) \
+        (cputime_to_usecs(__ct) * NSEC_PER_USEC)
+#endif
+
+#ifndef nsecs_to_cputime
+# define nsecs_to_cputime(__nsecs)      \
+        usecs_to_cputime((__nsecs) / NSEC_PER_USEC)
+#endif
+
+#endif /* __LINUX_CPUTIME_H */
diff --git a/include/linux/kernel_stat.h b/include/linux/kernel_stat.h
index 51c72be4a7c3..d7c61317db86 100644
--- a/include/linux/kernel_stat.h
+++ b/include/linux/kernel_stat.h
@@ -9,7 +9,7 @@
 #include <linux/sched.h>
 #include <linux/vtime.h>
 #include <asm/irq.h>
-#include <asm/cputime.h>
+#include <linux/cputime.h>
 
 /*
  * 'kernel_stat.h' contains the definitions needed for doing
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 825ed838d4b9..c399ed826648 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -29,7 +29,7 @@ struct sched_param {
 
 #include <asm/page.h>
 #include <asm/ptrace.h>
-#include <asm/cputime.h>
+#include <linux/cputime.h>
 
 #include <linux/smp.h>
 #include <linux/sem.h>
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index a47902c687ae..d11a1768357d 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -823,19 +823,13 @@ static void update_rq_clock_task(struct rq *rq, s64 delta)
 #endif
 #ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
         if (static_key_false((&paravirt_steal_rq_enabled))) {
-                u64 st;
-
                 steal = paravirt_steal_clock(cpu_of(rq));
                 steal -= rq->prev_steal_time_rq;
 
                 if (unlikely(steal > delta))
                         steal = delta;
 
-                st = steal_ticks(steal);
-                steal = st * TICK_NSEC;
-
                 rq->prev_steal_time_rq += steal;
-
                 delta -= steal;
         }
 #endif
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;
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index f2de7a175620..c9007f28d3a2 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1216,16 +1216,6 @@ extern void update_idle_cpu_load(struct rq *this_rq);
 
 extern void init_task_runnable_average(struct task_struct *p);
 
-#ifdef CONFIG_PARAVIRT
-static inline u64 steal_ticks(u64 steal)
-{
-        if (unlikely(steal > NSEC_PER_SEC))
-                return div_u64(steal, TICK_NSEC);
-
-        return __iter_div_u64_rem(steal, TICK_NSEC, &steal);
-}
-#endif
-
 static inline void inc_nr_running(struct rq *rq)
 {
         rq->nr_running++;