[RFC/PATCH 2/5] kernel_cpustat: convert to atomic 64-bit accessors

20 Feb 2013

Use the atomic64_* accessors for all the kernel_cpustat fields to
ensure atomic access on non-64 bit platforms.
Thanks to Mats Liljegren for CGROUP_CPUACCT related fixes.
Cc: Mats Liljegren mats.liljegren@enea.com
Signed-off-by: Kevin Hilman khilman@linaro.org
---
 fs/proc/stat.c              | 40 ++++++++++++++++++++--------------------
 fs/proc/uptime.c            |  2 +-
 include/linux/kernel_stat.h |  2 +-
 kernel/sched/core.c         | 10 +++++-----
 kernel/sched/cputime.c      | 38 +++++++++++++++++++-------------------
 5 files changed, 46 insertions(+), 46 deletions(-)

diff --git a/fs/proc/stat.c b/fs/proc/stat.c
index e296572..93f7f30 100644
--- a/fs/proc/stat.c
+++ b/fs/proc/stat.c
@@ -25,7 +25,7 @@ static cputime64_t get_idle_time(int cpu)
 {
    cputime64_t idle;
-	idle = kcpustat_cpu(cpu).cpustat[CPUTIME_IDLE];
+	idle = atomic64_read(&kcpustat_cpu(cpu).cpustat[CPUTIME_IDLE]);
    if (cpu_online(cpu) && !nr_iowait_cpu(cpu))
    	idle += arch_idle_time(cpu);
    return idle;
@@ -35,7 +35,7 @@ static cputime64_t get_iowait_time(int cpu)
 {
    cputime64_t iowait;
-	iowait = kcpustat_cpu(cpu).cpustat[CPUTIME_IOWAIT];
+	iowait = atomic64_read(&kcpustat_cpu(cpu).cpustat[CPUTIME_IOWAIT]);
    if (cpu_online(cpu) && nr_iowait_cpu(cpu))
    	iowait += arch_idle_time(cpu);
    return iowait;
@@ -52,7 +52,7 @@ static u64 get_idle_time(int cpu)
if (idle_time == -1ULL)
    	/* !NO_HZ or cpu offline so we can rely on cpustat.idle */
-		idle = kcpustat_cpu(cpu).cpustat[CPUTIME_IDLE];
+		idle = atomic64_read(&kcpustat_cpu(cpu).cpustat[CPUTIME_IDLE]);
    else
    	idle = usecs_to_cputime64(idle_time);
@@ -68,7 +68,7 @@ static u64 get_iowait_time(int cpu)
if (iowait_time == -1ULL)
    	/* !NO_HZ or cpu offline so we can rely on cpustat.iowait */
-		iowait = kcpustat_cpu(cpu).cpustat[CPUTIME_IOWAIT];
+		iowait = atomic64_read(&kcpustat_cpu(cpu).cpustat[CPUTIME_IOWAIT]);
    else
    	iowait = usecs_to_cputime64(iowait_time);
@@ -95,16 +95,16 @@ static int show_stat(struct seq_file *p, void *v)
    jif = boottime.tv_sec;
for_each_possible_cpu(i) {
-		user += kcpustat_cpu(i).cpustat[CPUTIME_USER];
-		nice += kcpustat_cpu(i).cpustat[CPUTIME_NICE];
-		system += kcpustat_cpu(i).cpustat[CPUTIME_SYSTEM];
+		user += atomic64_read(&kcpustat_cpu(i).cpustat[CPUTIME_USER]);
+		nice += atomic64_read(&kcpustat_cpu(i).cpustat[CPUTIME_NICE]);
+		system += atomic64_read(&kcpustat_cpu(i).cpustat[CPUTIME_SYSTEM]);
    	idle += get_idle_time(i);
    	iowait += get_iowait_time(i);
-		irq += kcpustat_cpu(i).cpustat[CPUTIME_IRQ];
-		softirq += kcpustat_cpu(i).cpustat[CPUTIME_SOFTIRQ];
-		steal += kcpustat_cpu(i).cpustat[CPUTIME_STEAL];
-		guest += kcpustat_cpu(i).cpustat[CPUTIME_GUEST];
-		guest_nice += kcpustat_cpu(i).cpustat[CPUTIME_GUEST_NICE];
+		irq += atomic64_read(&kcpustat_cpu(i).cpustat[CPUTIME_IRQ]);
+		softirq += atomic64_read(&kcpustat_cpu(i).cpustat[CPUTIME_SOFTIRQ]);
+		steal += atomic64_read(&kcpustat_cpu(i).cpustat[CPUTIME_STEAL]);
+		guest += atomic64_read(&kcpustat_cpu(i).cpustat[CPUTIME_GUEST]);
+		guest_nice += atomic64_read(&kcpustat_cpu(i).cpustat[CPUTIME_GUEST_NICE]);
    	sum += kstat_cpu_irqs_sum(i);
    	sum += arch_irq_stat_cpu(i);
@@ -132,16 +132,16 @@ static int show_stat(struct seq_file *p, void *v)
for_each_online_cpu(i) {
    	/* Copy values here to work around gcc-2.95.3, gcc-2.96 */
-		user = kcpustat_cpu(i).cpustat[CPUTIME_USER];
-		nice = kcpustat_cpu(i).cpustat[CPUTIME_NICE];
-		system = kcpustat_cpu(i).cpustat[CPUTIME_SYSTEM];
+		user = atomic64_read(&kcpustat_cpu(i).cpustat[CPUTIME_USER]);
+		nice = atomic64_read(&kcpustat_cpu(i).cpustat[CPUTIME_NICE]);
+		system = atomic64_read(&kcpustat_cpu(i).cpustat[CPUTIME_SYSTEM]);
    	idle = get_idle_time(i);
    	iowait = get_iowait_time(i);
-		irq = kcpustat_cpu(i).cpustat[CPUTIME_IRQ];
-		softirq = kcpustat_cpu(i).cpustat[CPUTIME_SOFTIRQ];
-		steal = kcpustat_cpu(i).cpustat[CPUTIME_STEAL];
-		guest = kcpustat_cpu(i).cpustat[CPUTIME_GUEST];
-		guest_nice = kcpustat_cpu(i).cpustat[CPUTIME_GUEST_NICE];
+		irq = atomic64_read(&kcpustat_cpu(i).cpustat[CPUTIME_IRQ]);
+		softirq = atomic64_read(&kcpustat_cpu(i).cpustat[CPUTIME_SOFTIRQ]);
+		steal = atomic64_read(&kcpustat_cpu(i).cpustat[CPUTIME_STEAL]);
+		guest = atomic64_read(&kcpustat_cpu(i).cpustat[CPUTIME_GUEST]);
+		guest_nice = atomic64_read(&kcpustat_cpu(i).cpustat[CPUTIME_GUEST_NICE]);
    	seq_printf(p, "cpu%d", i);
    	seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(user));
    	seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(nice));
diff --git a/fs/proc/uptime.c b/fs/proc/uptime.c
index 9610ac7..10c0f6e 100644
--- a/fs/proc/uptime.c
+++ b/fs/proc/uptime.c
@@ -18,7 +18,7 @@ static int uptime_proc_show(struct seq_file *m, void *v)
idletime = 0;
    for_each_possible_cpu(i)
-		idletime += (__force u64) kcpustat_cpu(i).cpustat[CPUTIME_IDLE];
+		idletime += atomic64_read(&kcpustat_cpu(i).cpustat[CPUTIME_IDLE]);
do_posix_clock_monotonic_gettime(&uptime);
    monotonic_to_bootbased(&uptime);
diff --git a/include/linux/kernel_stat.h b/include/linux/kernel_stat.h
index ed5f6ed..45b9f71 100644
--- a/include/linux/kernel_stat.h
+++ b/include/linux/kernel_stat.h
@@ -32,7 +32,7 @@ enum cpu_usage_stat {
 };
struct kernel_cpustat {
-	u64 cpustat[NR_STATS];
+	atomic64_t cpustat[NR_STATS];
 };
struct kernel_stat {
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 2fad439..5415e85 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -8168,8 +8168,8 @@ static int cpuacct_stats_show(struct cgroup *cgrp, struct cftype *cft,
for_each_online_cpu(cpu) {
    	struct kernel_cpustat *kcpustat = per_cpu_ptr(ca->cpustat, cpu);
-		val += kcpustat->cpustat[CPUTIME_USER];
-		val += kcpustat->cpustat[CPUTIME_NICE];
+		val += atomic64_read(&kcpustat->cpustat[CPUTIME_USER]);
+		val += atomic64_read(&kcpustat->cpustat[CPUTIME_NICE]);
    }
    val = cputime64_to_clock_t(val);
    cb->fill(cb, cpuacct_stat_desc[CPUACCT_STAT_USER], val);
@@ -8177,9 +8177,9 @@ static int cpuacct_stats_show(struct cgroup *cgrp, struct cftype *cft,
    val = 0;
    for_each_online_cpu(cpu) {
    	struct kernel_cpustat *kcpustat = per_cpu_ptr(ca->cpustat, cpu);
-		val += kcpustat->cpustat[CPUTIME_SYSTEM];
-		val += kcpustat->cpustat[CPUTIME_IRQ];
-		val += kcpustat->cpustat[CPUTIME_SOFTIRQ];
+		val += atomic64_read(&kcpustat->cpustat[CPUTIME_SYSTEM]);
+		val += atomic64_read(&kcpustat->cpustat[CPUTIME_IRQ]);
+		val += atomic64_read(&kcpustat->cpustat[CPUTIME_SOFTIRQ]);
    }
val = cputime64_to_clock_t(val);
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index ccff275..4c639ee 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -78,14 +78,14 @@ EXPORT_SYMBOL_GPL(irqtime_account_irq);
static int irqtime_account_hi_update(void)
 {
-	u64 *cpustat = kcpustat_this_cpu->cpustat;
+	atomic64_t *cpustat = kcpustat_this_cpu->cpustat;
    unsigned long flags;
    u64 latest_ns;
    int ret = 0;
local_irq_save(flags);
    latest_ns = this_cpu_read(cpu_hardirq_time);
-	if (nsecs_to_cputime64(latest_ns) > cpustat[CPUTIME_IRQ])
+	if (nsecs_to_cputime64(latest_ns) > atomic64_read(&cpustat[CPUTIME_IRQ]));
    	ret = 1;
    local_irq_restore(flags);
    return ret;
@@ -93,14 +93,14 @@ static int irqtime_account_hi_update(void)
static int irqtime_account_si_update(void)
 {
-	u64 *cpustat = kcpustat_this_cpu->cpustat;
+	atomic64_t *cpustat = kcpustat_this_cpu->cpustat;
    unsigned long flags;
    u64 latest_ns;
    int ret = 0;
local_irq_save(flags);
    latest_ns = this_cpu_read(cpu_softirq_time);
-	if (nsecs_to_cputime64(latest_ns) > cpustat[CPUTIME_SOFTIRQ])
+	if (nsecs_to_cputime64(latest_ns) > atomic64_read(&cpustat[CPUTIME_SOFTIRQ]))
    	ret = 1;
    local_irq_restore(flags);
    return ret;
@@ -125,7 +125,7 @@ static inline void task_group_account_field(struct task_struct *p, int index,
     * is the only cgroup, then nothing else should be necessary.
     *
     */
-	__get_cpu_var(kernel_cpustat).cpustat[index] += tmp;
+	atomic64_add(tmp, &__get_cpu_var(kernel_cpustat).cpustat[index]);
#ifdef CONFIG_CGROUP_CPUACCT
    if (unlikely(!cpuacct_subsys.active))
@@ -135,7 +135,7 @@ static inline void task_group_account_field(struct task_struct *p, int index,
    ca = task_ca(p);
    while (ca && (ca != &root_cpuacct)) {
    	kcpustat = this_cpu_ptr(ca->cpustat);
-		kcpustat->cpustat[index] += tmp;
+		atomic64_add(tmp, &kcpustat->cpustat[index]);
    	ca = parent_ca(ca);
    }
    rcu_read_unlock();
@@ -176,7 +176,7 @@ 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)
 {
-	u64 *cpustat = kcpustat_this_cpu->cpustat;
+	atomic64_t *cpustat = kcpustat_this_cpu->cpustat;
/* Add guest time to process. */
    p->utime += cputime;
@@ -186,11 +186,11 @@ static void account_guest_time(struct task_struct *p, cputime_t cputime,
/* Add guest time to cpustat. */
    if (TASK_NICE(p) > 0) {
-		cpustat[CPUTIME_NICE] += (__force u64) cputime;
-		cpustat[CPUTIME_GUEST_NICE] += (__force u64) cputime;
+		atomic64_add((__force u64) cputime, &cpustat[CPUTIME_NICE]);
+		atomic64_add((__force u64) cputime, &cpustat[CPUTIME_GUEST_NICE]);
    } else {
-		cpustat[CPUTIME_USER] += (__force u64) cputime;
-		cpustat[CPUTIME_GUEST] += (__force u64) cputime;
+		atomic64_add((__force u64) cputime, &cpustat[CPUTIME_USER]);
+		atomic64_add((__force u64) cputime, &cpustat[CPUTIME_GUEST]);
    }
 }
@@ -250,9 +250,9 @@ void account_system_time(struct task_struct *p, int hardirq_offset,
  */
 void account_steal_time(cputime_t cputime)
 {
-	u64 *cpustat = kcpustat_this_cpu->cpustat;
+	atomic64_t *cpustat = kcpustat_this_cpu->cpustat;
-	cpustat[CPUTIME_STEAL] += (__force u64) cputime;
+	atomic64_add((__force u64) cputime, &cpustat[CPUTIME_STEAL]);
 }
/*
@@ -261,13 +261,13 @@ void account_steal_time(cputime_t cputime)
  */
 void account_idle_time(cputime_t cputime)
 {
-	u64 *cpustat = kcpustat_this_cpu->cpustat;
+	atomic64_t *cpustat = kcpustat_this_cpu->cpustat;
    struct rq *rq = this_rq();
if (atomic_read(&rq->nr_iowait) > 0)
-		cpustat[CPUTIME_IOWAIT] += (__force u64) cputime;
+		atomic64_add((__force u64) cputime, &cpustat[CPUTIME_IOWAIT]);
    else
-		cpustat[CPUTIME_IDLE] += (__force u64) cputime;
+		atomic64_add((__force u64) cputime, &cpustat[CPUTIME_IDLE]);
 }
static __always_inline bool steal_account_process_tick(void)
@@ -345,15 +345,15 @@ 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);
-	u64 *cpustat = kcpustat_this_cpu->cpustat;
+	atomic64_t *cpustat = kcpustat_this_cpu->cpustat;
if (steal_account_process_tick())
    	return;
if (irqtime_account_hi_update()) {
-		cpustat[CPUTIME_IRQ] += (__force u64) cputime_one_jiffy;
+		atomic64_add((__force u64) cputime_one_jiffy, &cpustat[CPUTIME_IRQ]);
    } else if (irqtime_account_si_update()) {
-		cpustat[CPUTIME_SOFTIRQ] += (__force u64) cputime_one_jiffy;
+		atomic64_add((__force u64) cputime_one_jiffy, &cpustat[CPUTIME_SOFTIRQ]);
    } else if (this_cpu_ksoftirqd() == p) {
    	/*
    	 * ksoftirqd time do not get accounted in cpu_softirq_time.
-- 
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[RFC/PATCH 2/5] kernel_cpustat: convert to atomic 64-bit accessors