[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>

11 files changed, 116 insertions, 174 deletions

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;