[S390] cputime: add sparse checking and cleanup

Make cputime_t and cputime64_t nocast to enable sparse checking to
detect incorrect use of cputime. Drop the cputime macros for simple
scalar operations. The conversion macros are still needed.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

23 files changed, 323 insertions, 429 deletions

diff --git a/arch/ia64/include/asm/cputime.h b/arch/ia64/include/asm/cputime.h
index 6073b187528a..461e52f0277f 100644
--- a/arch/ia64/include/asm/cputime.h
+++ b/arch/ia64/include/asm/cputime.h
@@ -26,59 +26,51 @@
 #include <linux/jiffies.h>
 #include <asm/processor.h>
 
-typedef u64 cputime_t;
-typedef u64 cputime64_t;
+typedef u64 __nocast cputime_t;
+typedef u64 __nocast cputime64_t;
 
-#define cputime_zero			((cputime_t)0)
 #define cputime_one_jiffy		jiffies_to_cputime(1)
-#define cputime_max			((~((cputime_t)0) >> 1) - 1)
-#define cputime_add(__a, __b)		((__a) +  (__b))
-#define cputime_sub(__a, __b)		((__a) -  (__b))
-#define cputime_div(__a, __n)		((__a) /  (__n))
-#define cputime_halve(__a)		((__a) >> 1)
-#define cputime_eq(__a, __b)		((__a) == (__b))
-#define cputime_gt(__a, __b)		((__a) >  (__b))
-#define cputime_ge(__a, __b)		((__a) >= (__b))
-#define cputime_lt(__a, __b)		((__a) <  (__b))
-#define cputime_le(__a, __b)		((__a) <= (__b))
-
-#define cputime64_zero			((cputime64_t)0)
-#define cputime64_add(__a, __b)		((__a) + (__b))
-#define cputime64_sub(__a, __b)		((__a) - (__b))
-#define cputime_to_cputime64(__ct)	(__ct)
 
 /*
  * Convert cputime <-> jiffies (HZ)
  */
-#define cputime_to_jiffies(__ct)	((__ct) / (NSEC_PER_SEC / HZ))
-#define jiffies_to_cputime(__jif)	((__jif) * (NSEC_PER_SEC / HZ))
-#define cputime64_to_jiffies64(__ct)	((__ct) / (NSEC_PER_SEC / HZ))
-#define jiffies64_to_cputime64(__jif)	((__jif) * (NSEC_PER_SEC / HZ))
+#define cputime_to_jiffies(__ct)	\
+	((__force u64)(__ct) / (NSEC_PER_SEC / HZ))
+#define jiffies_to_cputime(__jif)	\
+	(__force cputime_t)((__jif) * (NSEC_PER_SEC / HZ))
+#define cputime64_to_jiffies64(__ct)	\
+	((__force u64)(__ct) / (NSEC_PER_SEC / HZ))
+#define jiffies64_to_cputime64(__jif)	\
+	(__force cputime64_t)((__jif) * (NSEC_PER_SEC / HZ))
 
 /*
  * Convert cputime <-> microseconds
  */
-#define cputime_to_usecs(__ct)		((__ct) / NSEC_PER_USEC)
-#define usecs_to_cputime(__usecs)	((__usecs) * NSEC_PER_USEC)
+#define cputime_to_usecs(__ct)		\
+	((__force u64)(__ct) / NSEC_PER_USEC)
+#define usecs_to_cputime(__usecs)	\
+	(__force cputime_t)((__usecs) * NSEC_PER_USEC)
 
 /*
  * Convert cputime <-> seconds
  */
-#define cputime_to_secs(__ct)		((__ct) / NSEC_PER_SEC)
-#define secs_to_cputime(__secs)		((__secs) * NSEC_PER_SEC)
+#define cputime_to_secs(__ct)		\
+	((__force u64)(__ct) / NSEC_PER_SEC)
+#define secs_to_cputime(__secs)		\
+	(__force cputime_t)((__secs) * NSEC_PER_SEC)
 
 /*
  * Convert cputime <-> timespec (nsec)
  */
 static inline cputime_t timespec_to_cputime(const struct timespec *val)
 {
-	cputime_t ret = val->tv_sec * NSEC_PER_SEC;
-	return (ret + val->tv_nsec);
+	u64 ret = val->tv_sec * NSEC_PER_SEC + val->tv_nsec;
+	return (__force cputime_t) ret;
 }
 static inline void cputime_to_timespec(const cputime_t ct, struct timespec *val)
 {
-	val->tv_sec  = ct / NSEC_PER_SEC;
-	val->tv_nsec = ct % NSEC_PER_SEC;
+	val->tv_sec  = (__force u64) ct / NSEC_PER_SEC;
+	val->tv_nsec = (__force u64) ct % NSEC_PER_SEC;
 }
 
 /*
@@ -86,25 +78,28 @@ static inline void cputime_to_timespec(const cputime_t ct, struct timespec *val)
  */
 static inline cputime_t timeval_to_cputime(struct timeval *val)
 {
-	cputime_t ret = val->tv_sec * NSEC_PER_SEC;
-	return (ret + val->tv_usec * NSEC_PER_USEC);
+	u64 ret = val->tv_sec * NSEC_PER_SEC + val->tv_usec * NSEC_PER_USEC;
+	return (__force cputime_t) ret;
 }
 static inline void cputime_to_timeval(const cputime_t ct, struct timeval *val)
 {
-	val->tv_sec = ct / NSEC_PER_SEC;
-	val->tv_usec = (ct % NSEC_PER_SEC) / NSEC_PER_USEC;
+	val->tv_sec = (__force u64) ct / NSEC_PER_SEC;
+	val->tv_usec = ((__force u64) ct % NSEC_PER_SEC) / NSEC_PER_USEC;
 }
 
 /*
  * Convert cputime <-> clock (USER_HZ)
  */
-#define cputime_to_clock_t(__ct)	((__ct) / (NSEC_PER_SEC / USER_HZ))
-#define clock_t_to_cputime(__x)		((__x) * (NSEC_PER_SEC / USER_HZ))
+#define cputime_to_clock_t(__ct)	\
+	((__force u64)(__ct) / (NSEC_PER_SEC / USER_HZ))
+#define clock_t_to_cputime(__x)		\
+	(__force cputime_t)((__x) * (NSEC_PER_SEC / USER_HZ))
 
 /*
  * Convert cputime64 to clock.
  */
-#define cputime64_to_clock_t(__ct)      cputime_to_clock_t((cputime_t)__ct)
+#define cputime64_to_clock_t(__ct)	\
+	cputime_to_clock_t((__force cputime_t)__ct)
 
 #endif /* CONFIG_VIRT_CPU_ACCOUNTING */
 #endif /* __IA64_CPUTIME_H */
diff --git a/arch/powerpc/include/asm/cputime.h b/arch/powerpc/include/asm/cputime.h
index 1cf20bdfbeca..e94935c52019 100644
--- a/arch/powerpc/include/asm/cputime.h
+++ b/arch/powerpc/include/asm/cputime.h
@@ -29,25 +29,8 @@ static inline void setup_cputime_one_jiffy(void) { }
 #include <asm/time.h>
 #include <asm/param.h>
 
-typedef u64 cputime_t;
-typedef u64 cputime64_t;
-
-#define cputime_zero			((cputime_t)0)
-#define cputime_max			((~((cputime_t)0) >> 1) - 1)
-#define cputime_add(__a, __b)		((__a) +  (__b))
-#define cputime_sub(__a, __b)		((__a) -  (__b))
-#define cputime_div(__a, __n)		((__a) /  (__n))
-#define cputime_halve(__a)		((__a) >> 1)
-#define cputime_eq(__a, __b)		((__a) == (__b))
-#define cputime_gt(__a, __b)		((__a) >  (__b))
-#define cputime_ge(__a, __b)		((__a) >= (__b))
-#define cputime_lt(__a, __b)		((__a) <  (__b))
-#define cputime_le(__a, __b)		((__a) <= (__b))
-
-#define cputime64_zero			((cputime64_t)0)
-#define cputime64_add(__a, __b)		((__a) + (__b))
-#define cputime64_sub(__a, __b)		((__a) - (__b))
-#define cputime_to_cputime64(__ct)	(__ct)
+typedef u64 __nocast cputime_t;
+typedef u64 __nocast cputime64_t;
 
 #ifdef __KERNEL__
 
@@ -65,7 +48,7 @@ DECLARE_PER_CPU(unsigned long, cputime_scaled_last_delta);
 
 static inline unsigned long cputime_to_jiffies(const cputime_t ct)
 {
-	return mulhdu(ct, __cputime_jiffies_factor);
+	return mulhdu((__force u64) ct, __cputime_jiffies_factor);
 }
 
 /* Estimate the scaled cputime by scaling the real cputime based on
@@ -74,14 +57,15 @@ static inline cputime_t cputime_to_scaled(const cputime_t ct)
 {
 	if (cpu_has_feature(CPU_FTR_SPURR) &&
 	    __get_cpu_var(cputime_last_delta))
-		return ct * __get_cpu_var(cputime_scaled_last_delta) /
-			    __get_cpu_var(cputime_last_delta);
+		return (__force u64) ct *
+			__get_cpu_var(cputime_scaled_last_delta) /
+			__get_cpu_var(cputime_last_delta);
 	return ct;
 }
 
 static inline cputime_t jiffies_to_cputime(const unsigned long jif)
 {
-	cputime_t ct;
+	u64 ct;
 	unsigned long sec;
 
 	/* have to be a little careful about overflow */
@@ -93,7 +77,7 @@ static inline cputime_t jiffies_to_cputime(const unsigned long jif)
 	}
 	if (sec)
 		ct += (cputime_t) sec * tb_ticks_per_sec;
-	return ct;
+	return (__force cputime_t) ct;
 }
 
 static inline void setup_cputime_one_jiffy(void)
@@ -103,7 +87,7 @@ static inline void setup_cputime_one_jiffy(void)
 
 static inline cputime64_t jiffies64_to_cputime64(const u64 jif)
 {
-	cputime_t ct;
+	u64 ct;
 	u64 sec;
 
 	/* have to be a little careful about overflow */
@@ -114,13 +98,13 @@ static inline cputime64_t jiffies64_to_cputime64(const u64 jif)
 		do_div(ct, HZ);
 	}
 	if (sec)
-		ct += (cputime_t) sec * tb_ticks_per_sec;
-	return ct;
+		ct += (u64) sec * tb_ticks_per_sec;
+	return (__force cputime64_t) ct;
 }
 
 static inline u64 cputime64_to_jiffies64(const cputime_t ct)
 {
-	return mulhdu(ct, __cputime_jiffies_factor);
+	return mulhdu((__force u64) ct, __cputime_jiffies_factor);
 }
 
 /*
@@ -130,12 +114,12 @@ extern u64 __cputime_msec_factor;
 
 static inline unsigned long cputime_to_usecs(const cputime_t ct)
 {
-	return mulhdu(ct, __cputime_msec_factor) * USEC_PER_MSEC;
+	return mulhdu((__force u64) ct, __cputime_msec_factor) * USEC_PER_MSEC;
 }
 
 static inline cputime_t usecs_to_cputime(const unsigned long us)
 {
-	cputime_t ct;
+	u64 ct;
 	unsigned long sec;
 
 	/* have to be a little careful about overflow */
@@ -147,7 +131,7 @@ static inline cputime_t usecs_to_cputime(const unsigned long us)
 	}
 	if (sec)
 		ct += (cputime_t) sec * tb_ticks_per_sec;
-	return ct;
+	return (__force cputime_t) ct;
 }
 
 /*
@@ -157,12 +141,12 @@ extern u64 __cputime_sec_factor;
 
 static inline unsigned long cputime_to_secs(const cputime_t ct)
 {
-	return mulhdu(ct, __cputime_sec_factor);
+	return mulhdu((__force u64) ct, __cputime_sec_factor);
 }
 
 static inline cputime_t secs_to_cputime(const unsigned long sec)
 {
-	return (cputime_t) sec * tb_ticks_per_sec;
+	return (__force cputime_t)((u64) sec * tb_ticks_per_sec);
 }
 
 /*
@@ -170,7 +154,7 @@ static inline cputime_t secs_to_cputime(const unsigned long sec)
  */
 static inline void cputime_to_timespec(const cputime_t ct, struct timespec *p)
 {
-	u64 x = ct;
+	u64 x = (__force u64) ct;
 	unsigned int frac;
 
 	frac = do_div(x, tb_ticks_per_sec);
@@ -182,11 +166,11 @@ static inline void cputime_to_timespec(const cputime_t ct, struct timespec *p)
 
 static inline cputime_t timespec_to_cputime(const struct timespec *p)
 {
-	cputime_t ct;
+	u64 ct;
 
 	ct = (u64) p->tv_nsec * tb_ticks_per_sec;
 	do_div(ct, 1000000000);
-	return ct + (u64) p->tv_sec * tb_ticks_per_sec;
+	return (__force cputime_t)(ct + (u64) p->tv_sec * tb_ticks_per_sec);
 }
 
 /*
@@ -194,7 +178,7 @@ static inline cputime_t timespec_to_cputime(const struct timespec *p)
  */
 static inline void cputime_to_timeval(const cputime_t ct, struct timeval *p)
 {
-	u64 x = ct;
+	u64 x = (__force u64) ct;
 	unsigned int frac;
 
 	frac = do_div(x, tb_ticks_per_sec);
@@ -206,11 +190,11 @@ static inline void cputime_to_timeval(const cputime_t ct, struct timeval *p)
 
 static inline cputime_t timeval_to_cputime(const struct timeval *p)
 {
-	cputime_t ct;
+	u64 ct;
 
 	ct = (u64) p->tv_usec * tb_ticks_per_sec;
 	do_div(ct, 1000000);
-	return ct + (u64) p->tv_sec * tb_ticks_per_sec;
+	return (__force cputime_t)(ct + (u64) p->tv_sec * tb_ticks_per_sec);
 }
 
 /*
@@ -220,12 +204,12 @@ extern u64 __cputime_clockt_factor;
 
 static inline unsigned long cputime_to_clock_t(const cputime_t ct)
 {
-	return mulhdu(ct, __cputime_clockt_factor);
+	return mulhdu((__force u64) ct, __cputime_clockt_factor);
 }
 
 static inline cputime_t clock_t_to_cputime(const unsigned long clk)
 {
-	cputime_t ct;
+	u64 ct;
 	unsigned long sec;
 
 	/* have to be a little careful about overflow */
@@ -236,8 +220,8 @@ static inline cputime_t clock_t_to_cputime(const unsigned long clk)
 		do_div(ct, USER_HZ);
 	}
 	if (sec)
-		ct += (cputime_t) sec * tb_ticks_per_sec;
-	return ct;
+		ct += (u64) sec * tb_ticks_per_sec;
+	return (__force cputime_t) ct;
 }
 
 #define cputime64_to_clock_t(ct)	cputime_to_clock_t((cputime_t)(ct))
diff --git a/arch/s390/include/asm/cputime.h b/arch/s390/include/asm/cputime.h
index 081434878296..0887a0463e33 100644
--- a/arch/s390/include/asm/cputime.h
+++ b/arch/s390/include/asm/cputime.h
@@ -16,114 +16,98 @@
 
 /* We want to use full resolution of the CPU timer: 2**-12 micro-seconds. */
 
-typedef unsigned long long cputime_t;
-typedef unsigned long long cputime64_t;
+typedef unsigned long long __nocast cputime_t;
+typedef unsigned long long __nocast cputime64_t;
 
-#ifndef __s390x__
-
-static inline unsigned int
-__div(unsigned long long n, unsigned int base)
+static inline unsigned long __div(unsigned long long n, unsigned long base)
 {
+#ifndef __s390x__
 	register_pair rp;
 
 	rp.pair = n >> 1;
 	asm ("dr %0,%1" : "+d" (rp) : "d" (base >> 1));
 	return rp.subreg.odd;
+#else /* __s390x__ */
+	return n / base;
+#endif /* __s390x__ */
 }
 
-#else /* __s390x__ */
+#define cputime_one_jiffy		jiffies_to_cputime(1)
 
-static inline unsigned int
-__div(unsigned long long n, unsigned int base)
+/*
+ * Convert cputime to jiffies and back.
+ */
+static inline unsigned long cputime_to_jiffies(const cputime_t cputime)
 {
-	return n / base;
+	return __div((__force unsigned long long) cputime, 4096000000ULL / HZ);
 }
 
-#endif /* __s390x__ */
+static inline cputime_t jiffies_to_cputime(const unsigned int jif)
+{
+	return (__force cputime_t)(jif * (4096000000ULL / HZ));
+}
 
-#define cputime_zero			(0ULL)
-#define cputime_one_jiffy		jiffies_to_cputime(1)
-#define cputime_max			((~0UL >> 1) - 1)
-#define cputime_add(__a, __b)		((__a) +  (__b))
-#define cputime_sub(__a, __b)		((__a) -  (__b))
-#define cputime_div(__a, __n) ({		\
-	unsigned long long __div = (__a);	\
-	do_div(__div,__n);			\
-	__div;					\
-})
-#define cputime_halve(__a)		((__a) >> 1)
-#define cputime_eq(__a, __b)		((__a) == (__b))
-#define cputime_gt(__a, __b)		((__a) >  (__b))
-#define cputime_ge(__a, __b)		((__a) >= (__b))
-#define cputime_lt(__a, __b)		((__a) <  (__b))
-#define cputime_le(__a, __b)		((__a) <= (__b))
-#define cputime_to_jiffies(__ct)	(__div((__ct), 4096000000ULL / HZ))
-#define cputime_to_scaled(__ct)		(__ct)
-#define jiffies_to_cputime(__hz)	((cputime_t)(__hz) * (4096000000ULL / HZ))
-
-#define cputime64_zero			(0ULL)
-#define cputime64_add(__a, __b)		((__a) + (__b))
-#define cputime_to_cputime64(__ct)	(__ct)
-
-static inline u64
-cputime64_to_jiffies64(cputime64_t cputime)
-{
-	do_div(cputime, 4096000000ULL / HZ);
-	return cputime;
+static inline u64 cputime64_to_jiffies64(cputime64_t cputime)
+{
+	unsigned long long jif = (__force unsigned long long) cputime;
+	do_div(jif, 4096000000ULL / HZ);
+	return jif;
+}
+
+static inline cputime64_t jiffies64_to_cputime64(const u64 jif)
+{
+	return (__force cputime64_t)(jif * (4096000000ULL / HZ));
 }
 
 /*
  * Convert cputime to microseconds and back.
  */
-static inline unsigned int
-cputime_to_usecs(const cputime_t cputime)
+static inline unsigned int cputime_to_usecs(const cputime_t cputime)
 {
-	return cputime_div(cputime, 4096);
+	return (__force unsigned long long) cputime >> 12;
 }
 
-static inline cputime_t
-usecs_to_cputime(const unsigned int m)
+static inline cputime_t usecs_to_cputime(const unsigned int m)
 {
-	return (cputime_t) m * 4096;
+	return (__force cputime_t)(m * 4096ULL);
 }
 
 /*
  * Convert cputime to milliseconds and back.
  */
-static inline unsigned int
-cputime_to_secs(const cputime_t cputime)
+static inline unsigned int cputime_to_secs(const cputime_t cputime)
 {
-	return __div(cputime, 2048000000) >> 1;
+	return __div((__force unsigned long long) cputime, 2048000000) >> 1;
 }
 
-static inline cputime_t
-secs_to_cputime(const unsigned int s)
+static inline cputime_t secs_to_cputime(const unsigned int s)
 {
-	return (cputime_t) s * 4096000000ULL;
+	return (__force cputime_t)(s * 4096000000ULL);
 }
 
 /*
  * Convert cputime to timespec and back.
  */
-static inline cputime_t
-timespec_to_cputime(const struct timespec *value)
+static inline cputime_t timespec_to_cputime(const struct timespec *value)
 {
-	return value->tv_nsec * 4096 / 1000 + (u64) value->tv_sec * 4096000000ULL;
+	unsigned long long ret = value->tv_sec * 4096000000ULL;
+	return (__force cputime_t)(ret + value->tv_nsec * 4096 / 1000);
 }
 
-static inline void
-cputime_to_timespec(const cputime_t cputime, struct timespec *value)
+static inline void cputime_to_timespec(const cputime_t cputime,
+				       struct timespec *value)
 {
+	unsigned long long __cputime = (__force unsigned long long) cputime;
 #ifndef __s390x__
 	register_pair rp;
 
-	rp.pair = cputime >> 1;
+	rp.pair = __cputime >> 1;
 	asm ("dr %0,%1" : "+d" (rp) : "d" (2048000000UL));
 	value->tv_nsec = rp.subreg.even * 1000 / 4096;
 	value->tv_sec = rp.subreg.odd;
 #else
-	value->tv_nsec = (cputime % 4096000000ULL) * 1000 / 4096;
-	value->tv_sec = cputime / 4096000000ULL;
+	value->tv_nsec = (__cputime % 4096000000ULL) * 1000 / 4096;
+	value->tv_sec = __cputime / 4096000000ULL;
 #endif
 }
 
@@ -132,50 +116,52 @@ cputime_to_timespec(const cputime_t cputime, struct timespec *value)
  * Since cputime and timeval have the same resolution (microseconds)
  * this is easy.
  */
-static inline cputime_t
-timeval_to_cputime(const struct timeval *value)
+static inline cputime_t timeval_to_cputime(const struct timeval *value)
 {
-	return value->tv_usec * 4096 + (u64) value->tv_sec * 4096000000ULL;
+	unsigned long long ret = value->tv_sec * 4096000000ULL;
+	return (__force cputime_t)(ret + value->tv_usec * 4096ULL);
 }
 
-static inline void
-cputime_to_timeval(const cputime_t cputime, struct timeval *value)
+static inline void cputime_to_timeval(const cputime_t cputime,
+				      struct timeval *value)
 {
+	unsigned long long __cputime = (__force unsigned long long) cputime;
 #ifndef __s390x__
 	register_pair rp;
 
-	rp.pair = cputime >> 1;
+	rp.pair = __cputime >> 1;
 	asm ("dr %0,%1" : "+d" (rp) : "d" (2048000000UL));
 	value->tv_usec = rp.subreg.even / 4096;
 	value->tv_sec = rp.subreg.odd;
 #else
-	value->tv_usec = (cputime % 4096000000ULL) / 4096;
-	value->tv_sec = cputime / 4096000000ULL;
+	value->tv_usec = (__cputime % 4096000000ULL) / 4096;
+	value->tv_sec = __cputime / 4096000000ULL;
 #endif
 }
 
 /*
  * Convert cputime to clock and back.
  */
-static inline clock_t
-cputime_to_clock_t(cputime_t cputime)
+static inline clock_t cputime_to_clock_t(cputime_t cputime)
 {
-	return cputime_div(cputime, 4096000000ULL / USER_HZ);
+	unsigned long long clock = (__force unsigned long long) cputime;
+	do_div(clock, 4096000000ULL / USER_HZ);
+	return clock;
 }
 
-static inline cputime_t
-clock_t_to_cputime(unsigned long x)
+static inline cputime_t clock_t_to_cputime(unsigned long x)
 {
-	return (cputime_t) x * (4096000000ULL / USER_HZ);
+	return (__force cputime_t)(x * (4096000000ULL / USER_HZ));
 }
 
 /*
  * Convert cputime64 to clock.
  */
-static inline clock_t
-cputime64_to_clock_t(cputime64_t cputime)
+static inline clock_t cputime64_to_clock_t(cputime64_t cputime)
 {
-       return cputime_div(cputime, 4096000000ULL / USER_HZ);
+	unsigned long long clock = (__force unsigned long long) cputime;
+	do_div(clock, 4096000000ULL / USER_HZ);
+	return clock;
 }
 
 struct s390_idle_data {
diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
index c97b468ee9f7..7f31a031c0b5 100644
--- a/drivers/cpufreq/cpufreq_conservative.c
+++ b/drivers/cpufreq/cpufreq_conservative.c
@@ -103,15 +103,14 @@ static inline cputime64_t get_cpu_idle_time_jiffy(unsigned int cpu,
 	cputime64_t busy_time;
 
 	cur_wall_time = jiffies64_to_cputime64(get_jiffies_64());
-	busy_time = cputime64_add(kstat_cpu(cpu).cpustat.user,
-			kstat_cpu(cpu).cpustat.system);
-
-	busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.irq);
-	busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.softirq);
-	busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.steal);
-	busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.nice);
-
-	idle_time = cputime64_sub(cur_wall_time, busy_time);
+	busy_time  = kstat_cpu(cpu).cpustat.user;
+	busy_time += kstat_cpu(cpu).cpustat.system;
+	busy_time += kstat_cpu(cpu).cpustat.irq;
+	busy_time += kstat_cpu(cpu).cpustat.softirq;
+	busy_time += kstat_cpu(cpu).cpustat.steal;
+	busy_time += kstat_cpu(cpu).cpustat.nice;
+
+	idle_time = cur_wall_time - busy_time;
 	if (wall)
 		*wall = (cputime64_t)jiffies_to_usecs(cur_wall_time);
 
@@ -353,20 +352,20 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
 
 		cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
 
-		wall_time = (unsigned int) cputime64_sub(cur_wall_time,
-				j_dbs_info->prev_cpu_wall);
+		wall_time = (unsigned int)
+			(cur_wall_time - j_dbs_info->prev_cpu_wall);
 		j_dbs_info->prev_cpu_wall = cur_wall_time;
 
-		idle_time = (unsigned int) cputime64_sub(cur_idle_time,
-				j_dbs_info->prev_cpu_idle);
+		idle_time = (unsigned int)
+			(cur_idle_time - j_dbs_info->prev_cpu_idle);
 		j_dbs_info->prev_cpu_idle = cur_idle_time;
 
 		if (dbs_tuners_ins.ignore_nice) {
 			cputime64_t cur_nice;
 			unsigned long cur_nice_jiffies;
 
-			cur_nice = cputime64_sub(kstat_cpu(j).cpustat.nice,
-					 j_dbs_info->prev_cpu_nice);
+			cur_nice = kstat_cpu(j).cpustat.nice -
+					j_dbs_info->prev_cpu_nice;
 			/*
 			 * Assumption: nice time between sampling periods will
 			 * be less than 2^32 jiffies for 32 bit sys
diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index fa8af4ebb1d6..07cffe2f6cff 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -127,15 +127,14 @@ static inline cputime64_t get_cpu_idle_time_jiffy(unsigned int cpu,
 	cputime64_t busy_time;
 
 	cur_wall_time = jiffies64_to_cputime64(get_jiffies_64());
-	busy_time = cputime64_add(kstat_cpu(cpu).cpustat.user,
-			kstat_cpu(cpu).cpustat.system);
-
-	busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.irq);
-	busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.softirq);
-	busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.steal);
-	busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.nice);
-
-	idle_time = cputime64_sub(cur_wall_time, busy_time);
+	busy_time  = kstat_cpu(cpu).cpustat.user;
+	busy_time += kstat_cpu(cpu).cpustat.system;
+	busy_time += kstat_cpu(cpu).cpustat.irq;
+	busy_time += kstat_cpu(cpu).cpustat.softirq;
+	busy_time += kstat_cpu(cpu).cpustat.steal;
+	busy_time += kstat_cpu(cpu).cpustat.nice;
+
+	idle_time = cur_wall_time - busy_time;
 	if (wall)
 		*wall = (cputime64_t)jiffies_to_usecs(cur_wall_time);
 
@@ -442,24 +441,24 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
 		cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
 		cur_iowait_time = get_cpu_iowait_time(j, &cur_wall_time);
 
-		wall_time = (unsigned int) cputime64_sub(cur_wall_time,
-				j_dbs_info->prev_cpu_wall);
+		wall_time = (unsigned int)
+			(cur_wall_time - j_dbs_info->prev_cpu_wall);
 		j_dbs_info->prev_cpu_wall = cur_wall_time;
 
-		idle_time = (unsigned int) cputime64_sub(cur_idle_time,
-				j_dbs_info->prev_cpu_idle);
+		idle_time = (unsigned int)
+			(cur_idle_time - j_dbs_info->prev_cpu_idle);
 		j_dbs_info->prev_cpu_idle = cur_idle_time;
 
-		iowait_time = (unsigned int) cputime64_sub(cur_iowait_time,
-				j_dbs_info->prev_cpu_iowait);
+		iowait_time = (unsigned int)
+			(cur_iowait_time - j_dbs_info->prev_cpu_iowait);
 		j_dbs_info->prev_cpu_iowait = cur_iowait_time;
 
 		if (dbs_tuners_ins.ignore_nice) {
 			cputime64_t cur_nice;
 			unsigned long cur_nice_jiffies;
 
-			cur_nice = cputime64_sub(kstat_cpu(j).cpustat.nice,
-					 j_dbs_info->prev_cpu_nice);
+			cur_nice = kstat_cpu(j).cpustat.nice -
+					j_dbs_info->prev_cpu_nice;
 			/*
 			 * Assumption: nice time between sampling periods will
 			 * be less than 2^32 jiffies for 32 bit sys
diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
index c5072a91e848..2a508edd768b 100644
--- a/drivers/cpufreq/cpufreq_stats.c
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -61,9 +61,8 @@ static int cpufreq_stats_update(unsigned int cpu)
 	spin_lock(&cpufreq_stats_lock);
 	stat = per_cpu(cpufreq_stats_table, cpu);
 	if (stat->time_in_state)
-		stat->time_in_state[stat->last_index] =
-			cputime64_add(stat->time_in_state[stat->last_index],
-				      cputime_sub(cur_time, stat->last_time));
+		stat->time_in_state[stat->last_index] +=
+			cur_time - stat->last_time;
 	stat->last_time = cur_time;
 	spin_unlock(&cpufreq_stats_lock);
 	return 0;
diff --git a/drivers/macintosh/rack-meter.c b/drivers/macintosh/rack-meter.c
index 2637c139777b..909908ebf164 100644
--- a/drivers/macintosh/rack-meter.c
+++ b/drivers/macintosh/rack-meter.c
@@ -83,11 +83,10 @@ static inline cputime64_t get_cpu_idle_time(unsigned int cpu)
 {
 	cputime64_t retval;
 
-	retval = cputime64_add(kstat_cpu(cpu).cpustat.idle,
-			kstat_cpu(cpu).cpustat.iowait);
+	retval = kstat_cpu(cpu).cpustat.idle + kstat_cpu(cpu).cpustat.iowait;
 
 	if (rackmeter_ignore_nice)
-		retval = cputime64_add(retval, kstat_cpu(cpu).cpustat.nice);
+		retval += kstat_cpu(cpu).cpustat.nice;
 
 	return retval;
 }
@@ -220,13 +219,11 @@ static void rackmeter_do_timer(struct work_struct *work)
 	int i, offset, load, cumm, pause;
 
 	cur_jiffies = jiffies64_to_cputime64(get_jiffies_64());
-	total_ticks = (unsigned int)cputime64_sub(cur_jiffies,
-						  rcpu->prev_wall);
+	total_ticks = (unsigned int) (cur_jiffies - rcpu->prev_wall);
 	rcpu->prev_wall = cur_jiffies;
 
 	total_idle_ticks = get_cpu_idle_time(cpu);
-	idle_ticks = (unsigned int) cputime64_sub(total_idle_ticks,
-				rcpu->prev_idle);
+	idle_ticks = (unsigned int) (total_idle_ticks - rcpu->prev_idle);
 	rcpu->prev_idle = total_idle_ticks;
 
 	/* We do a very dumb calculation to update the LEDs for now,
diff --git a/fs/proc/array.c b/fs/proc/array.c
index 3a1dafd228d1..8c344f037bd0 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -394,8 +394,8 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
 
 	sigemptyset(&sigign);
 	sigemptyset(&sigcatch);
-	cutime = cstime = utime = stime = cputime_zero;
-	cgtime = gtime = cputime_zero;
+	cutime = cstime = utime = stime = 0;
+	cgtime = gtime = 0;
 
 	if (lock_task_sighand(task, &flags)) {
 		struct signal_struct *sig = task->signal;
@@ -423,14 +423,14 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
 			do {
 				min_flt += t->min_flt;
 				maj_flt += t->maj_flt;
-				gtime = cputime_add(gtime, t->gtime);
+				gtime += t->gtime;
 				t = next_thread(t);
 			} while (t != task);
 
 			min_flt += sig->min_flt;
 			maj_flt += sig->maj_flt;
 			thread_group_times(task, &utime, &stime);
-			gtime = cputime_add(gtime, sig->gtime);
+			gtime += sig->gtime;
 		}
 
 		sid = task_session_nr_ns(task, ns);
diff --git a/fs/proc/stat.c b/fs/proc/stat.c
index 2a30d67dd6b8..714d5d131e76 100644
--- a/fs/proc/stat.c
+++ b/fs/proc/stat.c
@@ -30,7 +30,7 @@ static cputime64_t get_idle_time(int cpu)
 	if (idle_time == -1ULL) {
 		/* !NO_HZ so we can rely on cpustat.idle */
 		idle = kstat_cpu(cpu).cpustat.idle;
-		idle = cputime64_add(idle, arch_idle_time(cpu));
+		idle += arch_idle_time(cpu);
 	} else
 		idle = nsecs_to_jiffies64(1000 * idle_time);
 
@@ -63,23 +63,22 @@ static int show_stat(struct seq_file *p, void *v)
 	struct timespec boottime;
 
 	user = nice = system = idle = iowait =
-		irq = softirq = steal = cputime64_zero;
-	guest = guest_nice = cputime64_zero;
+		irq = softirq = steal = 0;
+	guest = guest_nice = 0;
 	getboottime(&boottime);
 	jif = boottime.tv_sec;
 
 	for_each_possible_cpu(i) {
-		user = cputime64_add(user, kstat_cpu(i).cpustat.user);
-		nice = cputime64_add(nice, kstat_cpu(i).cpustat.nice);
-		system = cputime64_add(system, kstat_cpu(i).cpustat.system);
-		idle = cputime64_add(idle, get_idle_time(i));
-		iowait = cputime64_add(iowait, get_iowait_time(i));
-		irq = cputime64_add(irq, kstat_cpu(i).cpustat.irq);
-		softirq = cputime64_add(softirq, kstat_cpu(i).cpustat.softirq);
-		steal = cputime64_add(steal, kstat_cpu(i).cpustat.steal);
-		guest = cputime64_add(guest, kstat_cpu(i).cpustat.guest);
-		guest_nice = cputime64_add(guest_nice,
-			kstat_cpu(i).cpustat.guest_nice);
+		user += kstat_cpu(i).cpustat.user;
+		nice += kstat_cpu(i).cpustat.nice;
+		system += kstat_cpu(i).cpustat.system;
+		idle += get_idle_time(i);
+		iowait += get_iowait_time(i);
+		irq += kstat_cpu(i).cpustat.irq;
+		softirq += kstat_cpu(i).cpustat.softirq;
+		steal += kstat_cpu(i).cpustat.steal;
+		guest += kstat_cpu(i).cpustat.guest;
+		guest_nice += kstat_cpu(i).cpustat.guest_nice;
 		sum += kstat_cpu_irqs_sum(i);
 		sum += arch_irq_stat_cpu(i);
 
diff --git a/fs/proc/uptime.c b/fs/proc/uptime.c
index 766b1d456050..ac5243657da3 100644
--- a/fs/proc/uptime.c
+++ b/fs/proc/uptime.c
@@ -12,10 +12,10 @@ static int uptime_proc_show(struct seq_file *m, void *v)
 	struct timespec uptime;
 	struct timespec idle;
 	int i;
-	cputime_t idletime = cputime_zero;
+	cputime_t idletime = 0;
 
 	for_each_possible_cpu(i)
-		idletime = cputime64_add(idletime, kstat_cpu(i).cpustat.idle);
+		idletime += kstat_cpu(i).cpustat.idle;
 
 	do_posix_clock_monotonic_gettime(&uptime);
 	monotonic_to_bootbased(&uptime);
diff --git a/include/asm-generic/cputime.h b/include/asm-generic/cputime.h
index 62ce6823c0f2..77202e2c9fc5 100644
--- a/include/asm-generic/cputime.h
+++ b/include/asm-generic/cputime.h
@@ -4,70 +4,64 @@
 #include <linux/time.h>
 #include <linux/jiffies.h>
 
-typedef unsigned long cputime_t;
+typedef unsigned long __nocast cputime_t;
 
-#define cputime_zero			(0UL)
 #define cputime_one_jiffy		jiffies_to_cputime(1)
-#define cputime_max			((~0UL >> 1) - 1)
-#define cputime_add(__a, __b)		((__a) +  (__b))
-#define cputime_sub(__a, __b)		((__a) -  (__b))
-#define cputime_div(__a, __n)		((__a) /  (__n))
-#define cputime_halve(__a)		((__a) >> 1)
-#define cputime_eq(__a, __b)		((__a) == (__b))
-#define cputime_gt(__a, __b)		((__a) >  (__b))
-#define cputime_ge(__a, __b)		((__a) >= (__b))
-#define cputime_lt(__a, __b)		((__a) <  (__b))
-#define cputime_le(__a, __b)		((__a) <= (__b))
-#define cputime_to_jiffies(__ct)	(__ct)
+#define cputime_to_jiffies(__ct)	(__force unsigned long)(__ct)
 #define cputime_to_scaled(__ct)		(__ct)
-#define jiffies_to_cputime(__hz)	(__hz)
+#define jiffies_to_cputime(__hz)	(__force cputime_t)(__hz)
 
-typedef u64 cputime64_t;
+typedef u64 __nocast cputime64_t;
 
-#define cputime64_zero (0ULL)
-#define cputime64_add(__a, __b)		((__a) + (__b))
-#define cputime64_sub(__a, __b)		((__a) - (__b))
-#define cputime64_to_jiffies64(__ct)	(__ct)
-#define jiffies64_to_cputime64(__jif)	(__jif)
-#define cputime_to_cputime64(__ct)	((u64) __ct)
-#define cputime64_gt(__a, __b)		((__a) >  (__b))
+#define cputime64_to_jiffies64(__ct)	(__force u64)(__ct)
+#define jiffies64_to_cputime64(__jif)	(__force cputime64_t)(__jif)
 
-#define nsecs_to_cputime64(__ct)	nsecs_to_jiffies64(__ct)
+#define nsecs_to_cputime64(__ct)	\
+	jiffies64_to_cputime64(nsecs_to_jiffies64(__ct))
 
 
 /*
  * Convert cputime to microseconds and back.
  */
-#define cputime_to_usecs(__ct)		jiffies_to_usecs(__ct)
-#define usecs_to_cputime(__msecs)	usecs_to_jiffies(__msecs)
+#define cputime_to_usecs(__ct)		\
+	jiffies_to_usecs(cputime_to_jiffies(__ct));
+#define usecs_to_cputime(__msecs)	\
+	jiffies_to_cputime(usecs_to_jiffies(__msecs));
 
 /*
  * Convert cputime to seconds and back.
  */
-#define cputime_to_secs(jif)		((jif) / HZ)
-#define secs_to_cputime(sec)		((sec) * HZ)
+#define cputime_to_secs(jif)		(cputime_to_jiffies(jif) / HZ)
+#define secs_to_cputime(sec)		jiffies_to_cputime((sec) * HZ)
 
 /*
  * Convert cputime to timespec and back.
  */
-#define timespec_to_cputime(__val)	timespec_to_jiffies(__val)
-#define cputime_to_timespec(__ct,__val)	jiffies_to_timespec(__ct,__val)
+#define timespec_to_cputime(__val)	\
+	jiffies_to_cputime(timespec_to_jiffies(__val))
+#define cputime_to_timespec(__ct,__val)	\
+	jiffies_to_timespec(cputime_to_jiffies(__ct),__val)
 
 /*
  * Convert cputime to timeval and back.
  */
-#define timeval_to_cputime(__val)	timeval_to_jiffies(__val)
-#define cputime_to_timeval(__ct,__val)	jiffies_to_timeval(__ct,__val)
+#define timeval_to_cputime(__val)	\
+	jiffies_to_cputime(timeval_to_jiffies(__val))
+#define cputime_to_timeval(__ct,__val)	\
+	jiffies_to_timeval(cputime_to_jiffies(__ct),__val)
 
 /*
  * Convert cputime to clock and back.
  */
-#define cputime_to_clock_t(__ct)	jiffies_to_clock_t(__ct)
-#define clock_t_to_cputime(__x)		clock_t_to_jiffies(__x)
+#define cputime_to_clock_t(__ct)	\
+	jiffies_to_clock_t(cputime_to_jiffies(__ct))
+#define clock_t_to_cputime(__x)		\
+	jiffies_to_cputime(clock_t_to_jiffies(__x))
 
 /*
  * Convert cputime64 to clock.
  */
-#define cputime64_to_clock_t(__ct)	jiffies_64_to_clock_t(__ct)
+#define cputime64_to_clock_t(__ct)	\
+	jiffies_64_to_clock_t(cputime64_to_jiffies64(__ct))
 
 #endif
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 1c4f3e9b9bc5..5649032d73fe 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -483,8 +483,8 @@ struct task_cputime {
 
 #define INIT_CPUTIME	\
 	(struct task_cputime) {					\
-		.utime = cputime_zero,				\
-		.stime = cputime_zero,				\
+		.utime = 0,					\
+		.stime = 0,					\
 		.sum_exec_runtime = 0,				\
 	}
 
diff --git a/kernel/acct.c b/kernel/acct.c
index fa7eb3de2ddc..203dfead2e06 100644
--- a/kernel/acct.c
+++ b/kernel/acct.c
@@ -613,8 +613,8 @@ void acct_collect(long exitcode, int group_dead)
 		pacct->ac_flag |= ACORE;
 	if (current->flags & PF_SIGNALED)
 		pacct->ac_flag |= AXSIG;
-	pacct->ac_utime = cputime_add(pacct->ac_utime, current->utime);
-	pacct->ac_stime = cputime_add(pacct->ac_stime, current->stime);
+	pacct->ac_utime += current->utime;
+	pacct->ac_stime += current->stime;
 	pacct->ac_minflt += current->min_flt;
 	pacct->ac_majflt += current->maj_flt;
 	spin_unlock_irq(&current->sighand->siglock);
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 563f13609470..3f8ee8a138c4 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -178,8 +178,7 @@ static inline void check_for_tasks(int cpu)
 	write_lock_irq(&tasklist_lock);
 	for_each_process(p) {
 		if (task_cpu(p) == cpu && p->state == TASK_RUNNING &&
-		    (!cputime_eq(p->utime, cputime_zero) ||
-		     !cputime_eq(p->stime, cputime_zero)))
+		    (p->utime || p->stime))
 			printk(KERN_WARNING "Task %s (pid = %d) is on cpu %d "
 				"(state = %ld, flags = %x)\n",
 				p->comm, task_pid_nr(p), cpu,
diff --git a/kernel/exit.c b/kernel/exit.c
index d0b7d988f873..5e0d1f4c696e 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -121,9 +121,9 @@ static void __exit_signal(struct task_struct *tsk)
 		 * We won't ever get here for the group leader, since it
 		 * will have been the last reference on the signal_struct.
 		 */
-		sig->utime = cputime_add(sig->utime, tsk->utime);
-		sig->stime = cputime_add(sig->stime, tsk->stime);
-		sig->gtime = cputime_add(sig->gtime, tsk->gtime);
+		sig->utime += tsk->utime;
+		sig->stime += tsk->stime;
+		sig->gtime += tsk->gtime;
 		sig->min_flt += tsk->min_flt;
 		sig->maj_flt += tsk->maj_flt;
 		sig->nvcsw += tsk->nvcsw;
@@ -1255,19 +1255,9 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
 		spin_lock_irq(&p->real_parent->sighand->siglock);
 		psig = p->real_parent->signal;
 		sig = p->signal;
-		psig->cutime =
-			cputime_add(psig->cutime,
-			cputime_add(tgutime,
-				    sig->cutime));
-		psig->cstime =
-			cputime_add(psig->cstime,
-			cputime_add(tgstime,
-				    sig->cstime));
-		psig->cgtime =
-			cputime_add(psig->cgtime,
-			cputime_add(p->gtime,
-			cputime_add(sig->gtime,
-				    sig->cgtime)));
+		psig->cutime += tgutime + sig->cutime;
+		psig->cstime += tgstime + sig->cstime;
+		psig->cgtime += p->gtime + sig->gtime + sig->cgtime;
 		psig->cmin_flt +=
 			p->min_flt + sig->min_flt + sig->cmin_flt;
 		psig->cmaj_flt +=
diff --git a/kernel/fork.c b/kernel/fork.c
index da4a6a10d088..b058c5820ecd 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1023,8 +1023,8 @@ void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
  */
 static void posix_cpu_timers_init(struct task_struct *tsk)
 {
-	tsk->cputime_expires.prof_exp = cputime_zero;
-	tsk->cputime_expires.virt_exp = cputime_zero;
+	tsk->cputime_expires.prof_exp = 0;
+	tsk->cputime_expires.virt_exp = 0;
 	tsk->cputime_expires.sched_exp = 0;
 	INIT_LIST_HEAD(&tsk->cpu_timers[0]);
 	INIT_LIST_HEAD(&tsk->cpu_timers[1]);
@@ -1132,14 +1132,10 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 
 	init_sigpending(&p->pending);
 
-	p->utime = cputime_zero;
-	p->stime = cputime_zero;
-	p->gtime = cputime_zero;
-	p->utimescaled = cputime_zero;
-	p->stimescaled = cputime_zero;
+	p->utime = p->stime = p->gtime = 0;
+	p->utimescaled = p->stimescaled = 0;
 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
-	p->prev_utime = cputime_zero;
-	p->prev_stime = cputime_zero;
+	p->prev_utime = p->prev_stime = 0;
 #endif
 #if defined(SPLIT_RSS_COUNTING)
 	memset(&p->rss_stat, 0, sizeof(p->rss_stat));
diff --git a/kernel/itimer.c b/kernel/itimer.c
index d802883153da..22000c3db0dd 100644
--- a/kernel/itimer.c
+++ b/kernel/itimer.c
@@ -52,22 +52,22 @@ static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
 
 	cval = it->expires;
 	cinterval = it->incr;
-	if (!cputime_eq(cval, cputime_zero)) {
+	if (cval) {
 		struct task_cputime cputime;
 		cputime_t t;
 
 		thread_group_cputimer(tsk, &cputime);
 		if (clock_id == CPUCLOCK_PROF)
-			t = cputime_add(cputime.utime, cputime.stime);
+			t = cputime.utime + cputime.stime;
 		else
 			/* CPUCLOCK_VIRT */
 			t = cputime.utime;
 
-		if (cputime_le(cval, t))
+		if (cval < t)
 			/* about to fire */
 			cval = cputime_one_jiffy;
 		else
-			cval = cputime_sub(cval, t);
+			cval = cval - t;
 	}
 
 	spin_unlock_irq(&tsk->sighand->siglock);
@@ -161,10 +161,9 @@ static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
 
 	cval = it->expires;
 	cinterval = it->incr;
-	if (!cputime_eq(cval, cputime_zero) ||
-	    !cputime_eq(nval, cputime_zero)) {
-		if (cputime_gt(nval, cputime_zero))
-			nval = cputime_add(nval, cputime_one_jiffy);
+	if (cval || nval) {
+		if (nval > 0)
+			nval += cputime_one_jiffy;
 		set_process_cpu_timer(tsk, clock_id, &nval, &cval);
 	}
 	it->expires = nval;
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index e7cb76dc18f5..125cb67daa21 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -78,7 +78,7 @@ static inline int cpu_time_before(const clockid_t which_clock,
 	if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
 		return now.sched < then.sched;
 	}  else {
-		return cputime_lt(now.cpu, then.cpu);
+		return now.cpu < then.cpu;
 	}
 }
 static inline void cpu_time_add(const clockid_t which_clock,
@@ -88,7 +88,7 @@ static inline void cpu_time_add(const clockid_t which_clock,
 	if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
 		acc->sched += val.sched;
 	}  else {
-		acc->cpu = cputime_add(acc->cpu, val.cpu);
+		acc->cpu += val.cpu;
 	}
 }
 static inline union cpu_time_count cpu_time_sub(const clockid_t which_clock,
@@ -98,25 +98,12 @@ static inline union cpu_time_count cpu_time_sub(const clockid_t which_clock,
 	if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
 		a.sched -= b.sched;
 	}  else {
-		a.cpu = cputime_sub(a.cpu, b.cpu);
+		a.cpu -= b.cpu;
 	}
 	return a;
 }
 
 /*
- * Divide and limit the result to res >= 1
- *
- * This is necessary to prevent signal delivery starvation, when the result of
- * the division would be rounded down to 0.
- */
-static inline cputime_t cputime_div_non_zero(cputime_t time, unsigned long div)
-{
-	cputime_t res = cputime_div(time, div);
-
-	return max_t(cputime_t, res, 1);
-}
-
-/*
  * Update expiry time from increment, and increase overrun count,
  * given the current clock sample.
  */
@@ -148,28 +135,26 @@ static void bump_cpu_timer(struct k_itimer *timer,
 	} else {
 		cputime_t delta, incr;
 
-		if (cputime_lt(now.cpu, timer->it.cpu.expires.cpu))
+		if (now.cpu < timer->it.cpu.expires.cpu)
 			return;
 		incr = timer->it.cpu.incr.cpu;
-		delta = cputime_sub(cputime_add(now.cpu, incr),
-				    timer->it.cpu.expires.cpu);
+		delta = now.cpu + incr - timer->it.cpu.expires.cpu;
 		/* Don't use (incr*2 < delta), incr*2 might overflow. */
-		for (i = 0; cputime_lt(incr, cputime_sub(delta, incr)); i++)
-			     incr = cputime_add(incr, incr);
-		for (; i >= 0; incr = cputime_halve(incr), i--) {
-			if (cputime_lt(delta, incr))
+		for (i = 0; incr < delta - incr; i++)
+			     incr += incr;
+		for (; i >= 0; incr = incr >> 1, i--) {
+			if (delta < incr)
 				continue;
-			timer->it.cpu.expires.cpu =
-				cputime_add(timer->it.cpu.expires.cpu, incr);
+			timer->it.cpu.expires.cpu += incr;
 			timer->it_overrun += 1 << i;
-			delta = cputime_sub(delta, incr);
+			delta -= incr;
 		}
 	}
 }
 
 static inline cputime_t prof_ticks(struct task_struct *p)
 {
-	return cputime_add(p->utime, p->stime);
+	return p->utime + p->stime;
 }
 static inline cputime_t virt_ticks(struct task_struct *p)
 {
@@ -248,8 +233,8 @@ void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
 
 	t = tsk;
 	do {
-		times->utime = cputime_add(times->utime, t->utime);
-		times->stime = cputime_add(times->stime, t->stime);
+		times->utime += t->utime;
+		times->stime += t->stime;
 		times->sum_exec_runtime += task_sched_runtime(t);
 	} while_each_thread(tsk, t);
 out:
@@ -258,10 +243,10 @@ out:
 
 static void update_gt_cputime(struct task_cputime *a, struct task_cputime *b)
 {
-	if (cputime_gt(b->utime, a->utime))
+	if (b->utime > a->utime)
 		a->utime = b->utime;
 
-	if (cputime_gt(b->stime, a->stime))
+	if (b->stime > a->stime)
 		a->stime = b->stime;
 
 	if (b->sum_exec_runtime > a->sum_exec_runtime)
@@ -306,7 +291,7 @@ static int cpu_clock_sample_group(const clockid_t which_clock,
 		return -EINVAL;
 	case CPUCLOCK_PROF:
 		thread_group_cputime(p, &cputime);
-		cpu->cpu = cputime_add(cputime.utime, cputime.stime);
+		cpu->cpu = cputime.utime + cputime.stime;
 		break;
 	case CPUCLOCK_VIRT:
 		thread_group_cputime(p, &cputime);
@@ -470,26 +455,24 @@ static void cleanup_timers(struct list_head *head,
 			   unsigned long long sum_exec_runtime)
 {
 	struct cpu_timer_list *timer, *next;
-	cputime_t ptime = cputime_add(utime, stime);
+	cputime_t ptime = utime + stime;
 
 	list_for_each_entry_safe(timer, next, head, entry) {
 		list_del_init(&timer->entry);
-		if (cputime_lt(timer->expires.cpu, ptime)) {
-			timer->expires.cpu = cputime_zero;
+		if (timer->expires.cpu < ptime) {
+			timer->expires.cpu = 0;
 		} else {
-			timer->expires.cpu = cputime_sub(timer->expires.cpu,
-							 ptime);
+			timer->expires.cpu -= ptime;
 		}
 	}
 
 	++head;
 	list_for_each_entry_safe(timer, next, head, entry) {
 		list_del_init(&timer->entry);
-		if (cputime_lt(timer->expires.cpu, utime)) {
-			timer->expires.cpu = cputime_zero;
+		if (timer->expires.cpu < utime) {
+			timer->expires.cpu = 0;
 		} else {
-			timer->expires.cpu = cputime_sub(timer->expires.cpu,
-							 utime);
+			timer->expires.cpu -= utime;
 		}
 	}
 
@@ -520,8 +503,7 @@ void posix_cpu_timers_exit_group(struct task_struct *tsk)
 	struct signal_struct *const sig = tsk->signal;
 
 	cleanup_timers(tsk->signal->cpu_timers,
-		       cputime_add(tsk->utime, sig->utime),
-		       cputime_add(tsk->stime, sig->stime),
+		       tsk->utime + sig->utime, tsk->stime + sig->stime,
 		       tsk->se.sum_exec_runtime + sig->sum_sched_runtime);
 }
 
@@ -540,8 +522,7 @@ static void clear_dead_task(struct k_itimer *timer, union cpu_time_count now)
 
 static inline int expires_gt(cputime_t expires, cputime_t new_exp)
 {
-	return cputime_eq(expires, cputime_zero) ||
-	       cputime_gt(expires, new_exp);
+	return expires == 0 || expires > new_exp;
 }
 
 /*
@@ -651,7 +632,7 @@ static int cpu_timer_sample_group(const clockid_t which_clock,
 	default:
 		return -EINVAL;
 	case CPUCLOCK_PROF:
-		cpu->cpu = cputime_add(cputime.utime, cputime.stime);
+		cpu->cpu = cputime.utime + cputime.stime;
 		break;
 	case CPUCLOCK_VIRT:
 		cpu->cpu = cputime.utime;
@@ -918,12 +899,12 @@ static void check_thread_timers(struct task_struct *tsk,
 	unsigned long soft;
 
 	maxfire = 20;
-	tsk->cputime_expires.prof_exp = cputime_zero;
+	tsk->cputime_expires.prof_exp = 0;
 	while (!list_empty(timers)) {
 		struct cpu_timer_list *t = list_first_entry(timers,
 						      struct cpu_timer_list,
 						      entry);
-		if (!--maxfire || cputime_lt(prof_ticks(tsk), t->expires.cpu)) {
+		if (!--maxfire || prof_ticks(tsk) < t->expires.cpu) {
 			tsk->cputime_expires.prof_exp = t->expires.cpu;
 			break;
 		}
@@ -933,12 +914,12 @@ static void check_thread_timers(struct task_struct *tsk,
 
 	++timers;
 	maxfire = 20;
-	tsk->cputime_expires.virt_exp = cputime_zero;
+	tsk->cputime_expires.virt_exp = 0;
 	while (!list_empty(timers)) {
 		struct cpu_timer_list *t = list_first_entry(timers,
 						      struct cpu_timer_list,
 						      entry);
-		if (!--maxfire || cputime_lt(virt_ticks(tsk), t->expires.cpu)) {
+		if (!--maxfire || virt_ticks(tsk) < t->expires.cpu) {
 			tsk->cputime_expires.virt_exp = t->expires.cpu;
 			break;
 		}
@@ -1009,20 +990,19 @@ static u32 onecputick;
 static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
 			     cputime_t *expires, cputime_t cur_time, int signo)
 {
-	if (cputime_eq(it->expires, cputime_zero))
+	if (!it->expires)
 		return;
 
-	if (cputime_ge(cur_time, it->expires)) {
-		if (!cputime_eq(it->incr, cputime_zero)) {
-			it->expires = cputime_add(it->expires, it->incr);
+	if (cur_time >= it->expires) {
+		if (it->incr) {
+			it->expires += it->incr;
 			it->error += it->incr_error;
 			if (it->error >= onecputick) {
-				it->expires = cputime_sub(it->expires,
-							  cputime_one_jiffy);
+				it->expires -= cputime_one_jiffy;
 				it->error -= onecputick;
 			}
 		} else {
-			it->expires = cputime_zero;
+			it->expires = 0;
 		}
 
 		trace_itimer_expire(signo == SIGPROF ?
@@ -1031,9 +1011,7 @@ static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
 		__group_send_sig_info(signo, SEND_SIG_PRIV, tsk);
 	}
 
-	if (!cputime_eq(it->expires, cputime_zero) &&
-	    (cputime_eq(*expires, cputime_zero) ||
-	     cputime_lt(it->expires, *expires))) {
+	if (it->expires && (!*expires || it->expires < *expires)) {
 		*expires = it->expires;
 	}
 }
@@ -1048,9 +1026,7 @@ static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
  */
 static inline int task_cputime_zero(const struct task_cputime *cputime)
 {
-	if (cputime_eq(cputime->utime, cputime_zero) &&
-	    cputime_eq(cputime->stime, cputime_zero) &&
-	    cputime->sum_exec_runtime == 0)
+	if (!cputime->utime && !cputime->stime && !cputime->sum_exec_runtime)
 		return 1;
 	return 0;
 }
@@ -1076,15 +1052,15 @@ static void check_process_timers(struct task_struct *tsk,
 	 */
 	thread_group_cputimer(tsk, &cputime);
 	utime = cputime.utime;
-	ptime = cputime_add(utime, cputime.stime);
+	ptime = utime + cputime.stime;
 	sum_sched_runtime = cputime.sum_exec_runtime;
 	maxfire = 20;
-	prof_expires = cputime_zero;
+	prof_expires = 0;
 	while (!list_empty(timers)) {
 		struct cpu_timer_list *tl = list_first_entry(timers,
 						      struct cpu_timer_list,
 						      entry);
-		if (!--maxfire || cputime_lt(ptime, tl->expires.cpu)) {
+		if (!--maxfire || ptime < tl->expires.cpu) {
 			prof_expires = tl->expires.cpu;
 			break;
 		}
@@ -1094,12 +1070,12 @@ static void check_process_timers(struct task_struct *tsk,
 
 	++timers;
 	maxfire = 20;
-	virt_expires = cputime_zero;
+	virt_expires = 0;
 	while (!list_empty(timers)) {
 		struct cpu_timer_list *tl = list_first_entry(timers,
 						      struct cpu_timer_list,
 						      entry);
-		if (!--maxfire || cputime_lt(utime, tl->expires.cpu)) {
+		if (!--maxfire || utime < tl->expires.cpu) {
 			virt_expires = tl->expires.cpu;
 			break;
 		}
@@ -1154,8 +1130,7 @@ static void check_process_timers(struct task_struct *tsk,
 			}
 		}
 		x = secs_to_cputime(soft);
-		if (cputime_eq(prof_expires, cputime_zero) ||
-		    cputime_lt(x, prof_expires)) {
+		if (!prof_expires || x < prof_expires) {
 			prof_expires = x;
 		}
 	}
@@ -1249,12 +1224,9 @@ out:
 static inline int task_cputime_expired(const struct task_cputime *sample,
 					const struct task_cputime *expires)
 {
-	if (!cputime_eq(expires->utime, cputime_zero) &&
-	    cputime_ge(sample->utime, expires->utime))
+	if (expires->utime && sample->utime >= expires->utime)
 		return 1;
-	if (!cputime_eq(expires->stime, cputime_zero) &&
-	    cputime_ge(cputime_add(sample->utime, sample->stime),
-		       expires->stime))
+	if (expires->stime && sample->utime + sample->stime >= expires->stime)
 		return 1;
 	if (expires->sum_exec_runtime != 0 &&
 	    sample->sum_exec_runtime >= expires->sum_exec_runtime)
@@ -1389,18 +1361,18 @@ void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
 		 * it to be relative, *newval argument is relative and we update
 		 * it to be absolute.
 		 */
-		if (!cputime_eq(*oldval, cputime_zero)) {
-			if (cputime_le(*oldval, now.cpu)) {
+		if (*oldval) {
+			if (*oldval <= now.cpu) {
 				/* Just about to fire. */
 				*oldval = cputime_one_jiffy;
 			} else {
-				*oldval = cputime_sub(*oldval, now.cpu);
+				*oldval -= now.cpu;
 			}
 		}
 
-		if (cputime_eq(*newval, cputime_zero))
+		if (!*newval)
 			return;
-		*newval = cputime_add(*newval, now.cpu);
+		*newval += now.cpu;
 	}
 
 	/*
diff --git a/kernel/sched.c b/kernel/sched.c
index d6b149ccf925..18cad4467e61 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2166,7 +2166,7 @@ static int irqtime_account_hi_update(void)
 
 	local_irq_save(flags);
 	latest_ns = this_cpu_read(cpu_hardirq_time);
-	if (cputime64_gt(nsecs_to_cputime64(latest_ns), cpustat->irq))
+	if (nsecs_to_cputime64(latest_ns) > cpustat->irq)
 		ret = 1;
 	local_irq_restore(flags);
 	return ret;
@@ -2181,7 +2181,7 @@ static int irqtime_account_si_update(void)
 
 	local_irq_save(flags);
 	latest_ns = this_cpu_read(cpu_softirq_time);
-	if (cputime64_gt(nsecs_to_cputime64(latest_ns), cpustat->softirq))
+	if (nsecs_to_cputime64(latest_ns) > cpustat->softirq)
 		ret = 1;
 	local_irq_restore(flags);
 	return ret;
@@ -3868,19 +3868,17 @@ void account_user_time(struct task_struct *p, cputime_t cputime,
 		       cputime_t cputime_scaled)
 {
 	struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
-	cputime64_t tmp;
 
 	/* Add user time to process. */
-	p->utime = cputime_add(p->utime, cputime);
-	p->utimescaled = cputime_add(p->utimescaled, cputime_scaled);
+	p->utime += cputime;
+	p->utimescaled += cputime_scaled;
 	account_group_user_time(p, cputime);
 
 	/* Add user time to cpustat. */
-	tmp = cputime_to_cputime64(cputime);
 	if (TASK_NICE(p) > 0)
-		cpustat->nice = cputime64_add(cpustat->nice, tmp);
+		cpustat->nice += (__force cputime64_t) cputime;
 	else
-		cpustat->user = cputime64_add(cpustat->user, tmp);
+		cpustat->user += (__force cputime64_t) cputime;
 
 	cpuacct_update_stats(p, CPUACCT_STAT_USER, cputime);
 	/* Account for user time used */
@@ -3896,24 +3894,21 @@ void account_user_time(struct task_struct *p, cputime_t cputime,
 static void account_guest_time(struct task_struct *p, cputime_t cputime,
 			       cputime_t cputime_scaled)
 {
-	cputime64_t tmp;
 	struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
 
-	tmp = cputime_to_cputime64(cputime);
-
 	/* Add guest time to process. */
-	p->utime = cputime_add(p->utime, cputime);
-	p->utimescaled = cputime_add(p->utimescaled, cputime_scaled);
+	p->utime += cputime;
+	p->utimescaled += cputime_scaled;
 	account_group_user_time(p, cputime);
-	p->gtime = cputime_add(p->gtime, cputime);
+	p->gtime += cputime;
 
 	/* Add guest time to cpustat. */
 	if (TASK_NICE(p) > 0) {
-		cpustat->nice = cputime64_add(cpustat->nice, tmp);
-		cpustat->guest_nice = cputime64_add(cpustat->guest_nice, tmp);
+		cpustat->nice += (__force cputime64_t) cputime;
+		cpustat->guest_nice += (__force cputime64_t) cputime;
 	} else {
-		cpustat->user = cputime64_add(cpustat->user, tmp);
-		cpustat->guest = cputime64_add(cpustat->guest, tmp);
+		cpustat->user += (__force cputime64_t) cputime;
+		cpustat->guest += (__force cputime64_t) cputime;
 	}
 }
 
@@ -3928,15 +3923,13 @@ static inline
 void __account_system_time(struct task_struct *p, cputime_t cputime,
 			cputime_t cputime_scaled, cputime64_t *target_cputime64)
 {
-	cputime64_t tmp = cputime_to_cputime64(cputime);
-
 	/* Add system time to process. */
-	p->stime = cputime_add(p->stime, cputime);
-	p->stimescaled = cputime_add(p->stimescaled, cputime_scaled);
+	p->stime += cputime;
+	p->stimescaled += cputime_scaled;
 	account_group_system_time(p, cputime);
 
 	/* Add system time to cpustat. */
-	*target_cputime64 = cputime64_add(*target_cputime64, tmp);
+	*target_cputime64 += (__force cputime64_t) cputime;
 	cpuacct_update_stats(p, CPUACCT_STAT_SYSTEM, cputime);
 
 	/* Account for system time used */
@@ -3978,9 +3971,8 @@ void account_system_time(struct task_struct *p, int hardirq_offset,
 void account_steal_time(cputime_t cputime)
 {
 	struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
-	cputime64_t cputime64 = cputime_to_cputime64(cputime);
 
-	cpustat->steal = cputime64_add(cpustat->steal, cputime64);
+	cpustat->steal += (__force cputime64_t) cputime;
 }
 
 /*
@@ -3990,13 +3982,12 @@ void account_steal_time(cputime_t cputime)
 void account_idle_time(cputime_t cputime)
 {
 	struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
-	cputime64_t cputime64 = cputime_to_cputime64(cputime);
 	struct rq *rq = this_rq();
 
 	if (atomic_read(&rq->nr_iowait) > 0)
-		cpustat->iowait = cputime64_add(cpustat->iowait, cputime64);
+		cpustat->iowait += (__force cputime64_t) cputime;
 	else
-		cpustat->idle = cputime64_add(cpustat->idle, cputime64);
+		cpustat->idle += (__force cputime64_t) cputime;
 }
 
 static __always_inline bool steal_account_process_tick(void)
@@ -4046,16 +4037,15 @@ static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
 						struct rq *rq)
 {
 	cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
-	cputime64_t tmp = cputime_to_cputime64(cputime_one_jiffy);
 	struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
 
 	if (steal_account_process_tick())
 		return;
 
 	if (irqtime_account_hi_update()) {
-		cpustat->irq = cputime64_add(cpustat->irq, tmp);
+		cpustat->irq += (__force cputime64_t) cputime_one_jiffy;
 	} else if (irqtime_account_si_update()) {
-		cpustat->softirq = cputime64_add(cpustat->softirq, tmp);
+		cpustat->softirq += (__force cputime64_t) cputime_one_jiffy;
 	} else if (this_cpu_ksoftirqd() == p) {
 		/*
 		 * ksoftirqd time do not get accounted in cpu_softirq_time.
@@ -4171,7 +4161,7 @@ void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
 
 void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
 {
-	cputime_t rtime, utime = p->utime, total = cputime_add(utime, p->stime);
+	cputime_t rtime, utime = p->utime, total = utime + p->stime;
 
 	/*
 	 * Use CFS's precise accounting:
@@ -4179,11 +4169,11 @@ void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
 	rtime = nsecs_to_cputime(p->se.sum_exec_runtime);
 
 	if (total) {
-		u64 temp = rtime;
+		u64 temp = (__force u64) rtime;
 
-		temp *= utime;
-		do_div(temp, total);
-		utime = (cputime_t)temp;
+		temp *= (__force u64) utime;
+		do_div(temp, (__force u32) total);
+		utime = (__force cputime_t) temp;
 	} else
 		utime = rtime;
 
@@ -4191,7 +4181,7 @@ void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
 	 * Compare with previous values, to keep monotonicity:
 	 */
 	p->prev_utime = max(p->prev_utime, utime);
-	p->prev_stime = max(p->prev_stime, cputime_sub(rtime, p->prev_utime));
+	p->prev_stime = max(p->prev_stime, rtime - p->prev_utime);
 
 	*ut = p->prev_utime;
 	*st = p->prev_stime;
@@ -4208,21 +4198,20 @@ void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
 
 	thread_group_cputime(p, &cputime);
 
-	total = cputime_add(cputime.utime, cputime.stime);
+	total = cputime.utime + cputime.stime;
 	rtime = nsecs_to_cputime(cputime.sum_exec_runtime);
 
 	if (total) {
-		u64 temp = rtime;
+		u64 temp = (__force u64) rtime;
 
-		temp *= cputime.utime;
-		do_div(temp, total);
-		utime = (cputime_t)temp;
+		temp *= (__force u64) cputime.utime;
+		do_div(temp, (__force u32) total);
+		utime = (__force cputime_t) temp;
 	} else
 		utime = rtime;
 
 	sig->prev_utime = max(sig->prev_utime, utime);
-	sig->prev_stime = max(sig->prev_stime,
-			      cputime_sub(rtime, sig->prev_utime));
+	sig->prev_stime = max(sig->prev_stime, rtime - sig->prev_utime);
 
 	*ut = sig->prev_utime;
 	*st = sig->prev_stime;
@@ -9769,7 +9758,8 @@ static void cpuacct_update_stats(struct task_struct *tsk,
 	ca = task_ca(tsk);
 
 	do {
-		__percpu_counter_add(&ca->cpustat[idx], val, batch);
+		__percpu_counter_add(&ca->cpustat[idx],
+				     (__force s64) val, batch);
 		ca = ca->parent;
 	} while (ca);
 	rcu_read_unlock();
diff --git a/kernel/sched_stats.h b/kernel/sched_stats.h
index 87f9e36ea56e..4b71dbef271d 100644
--- a/kernel/sched_stats.h
+++ b/kernel/sched_stats.h
@@ -283,8 +283,7 @@ static inline void account_group_user_time(struct task_struct *tsk,
 		return;
 
 	raw_spin_lock(&cputimer->lock);
-	cputimer->cputime.utime =
-		cputime_add(cputimer->cputime.utime, cputime);
+	cputimer->cputime.utime += cputime;
 	raw_spin_unlock(&cputimer->lock);
 }
 
@@ -307,8 +306,7 @@ static inline void account_group_system_time(struct task_struct *tsk,
 		return;
 
 	raw_spin_lock(&cputimer->lock);
-	cputimer->cputime.stime =
-		cputime_add(cputimer->cputime.stime, cputime);
+	cputimer->cputime.stime += cputime;
 	raw_spin_unlock(&cputimer->lock);
 }
 
diff --git a/kernel/signal.c b/kernel/signal.c
index b3f78d09a105..739ef2bf105c 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1629,10 +1629,8 @@ bool do_notify_parent(struct task_struct *tsk, int sig)
 	info.si_uid = __task_cred(tsk)->uid;
 	rcu_read_unlock();
 
-	info.si_utime = cputime_to_clock_t(cputime_add(tsk->utime,
-				tsk->signal->utime));
-	info.si_stime = cputime_to_clock_t(cputime_add(tsk->stime,
-				tsk->signal->stime));
+	info.si_utime = cputime_to_clock_t(tsk->utime + tsk->signal->utime);
+	info.si_stime = cputime_to_clock_t(tsk->stime + tsk->signal->stime);
 
 	info.si_status = tsk->exit_code & 0x7f;
 	if (tsk->exit_code & 0x80)
diff --git a/kernel/sys.c b/kernel/sys.c
index 481611fbd079..ddf8155bf3f8 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1605,7 +1605,7 @@ static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
 	unsigned long maxrss = 0;
 
 	memset((char *) r, 0, sizeof *r);
-	utime = stime = cputime_zero;
+	utime = stime = 0;
 
 	if (who == RUSAGE_THREAD) {
 		task_times(current, &utime, &stime);
@@ -1635,8 +1635,8 @@ static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
 
 		case RUSAGE_SELF:
 			thread_group_times(p, &tgutime, &tgstime);
-			utime = cputime_add(utime, tgutime);
-			stime = cputime_add(stime, tgstime);
+			utime += tgutime;
+			stime += tgstime;
 			r->ru_nvcsw += p->signal->nvcsw;
 			r->ru_nivcsw += p->signal->nivcsw;
 			r->ru_minflt += p->signal->min_flt;
diff --git a/kernel/tsacct.c b/kernel/tsacct.c
index 5bbfac85866e..23b4d784ebdd 100644
--- a/kernel/tsacct.c
+++ b/kernel/tsacct.c
@@ -127,7 +127,7 @@ void acct_update_integrals(struct task_struct *tsk)
 
 		local_irq_save(flags);
 		time = tsk->stime + tsk->utime;
-		dtime = cputime_sub(time, tsk->acct_timexpd);
+		dtime = time - tsk->acct_timexpd;
 		jiffies_to_timeval(cputime_to_jiffies(dtime), &value);
 		delta = value.tv_sec;
 		delta = delta * USEC_PER_SEC + value.tv_usec;