[PATCH] Use for_each_cpu() Where It's Meant To Be

From: Rusty Russell <rusty@rustcorp.com.au>

Some places use cpu_online() where they should be using cpu_possible, most
commonly for tallying statistics.  This makes no difference without hotplug
CPU.

Use the for_each_cpu() macro in those places, providing good examples (and
making the external hotplug CPU patch smaller).

Some places use cpu_online() where they should be using cpu_possible, most
commonly for tallying statistics.  This makes no difference without hotplug
CPU.

Use the for_each_cpu() macro in those places, providing good examples (and
making the external hotplug CPU patch smaller).

drivers/oprofile/oprofile_stats.c

@@ -9,6 +9,7 @@
 
 #include <linux/oprofile.h>
 #include <linux/smp.h>
+#include <linux/cpumask.h>
 #include <linux/threads.h>
  
 #include "oprofile_stats.h"

fs/buffer.c

@@ -2940,10 +2940,8 @@ static void recalc_bh_state(void)
 	if (__get_cpu_var(bh_accounting).ratelimit++ < 4096)
 		return;
 	__get_cpu_var(bh_accounting).ratelimit = 0;
-	for (i = 0; i < NR_CPUS; i++) {
-		if (cpu_online(i))
-			tot += per_cpu(bh_accounting, i).nr;
-	}
+	for_each_cpu(i)
+		tot += per_cpu(bh_accounting, i).nr;
 	buffer_heads_over_limit = (tot > max_buffer_heads);
 }
 	

fs/proc/proc_misc.c

@@ -378,10 +378,9 @@ int show_stat(struct seq_file *p, void *v)
 	jif = ((u64)now.tv_sec * HZ) + (now.tv_usec/(1000000/HZ)) - jif;
 	do_div(jif, HZ);
 
-	for (i = 0; i < NR_CPUS; i++) {
+	for_each_cpu(i) {
 		int j;
 
-		if (!cpu_online(i)) continue;
 		user += kstat_cpu(i).cpustat.user;
 		nice += kstat_cpu(i).cpustat.nice;
 		system += kstat_cpu(i).cpustat.system;
@@ -401,8 +400,7 @@ int show_stat(struct seq_file *p, void *v)
 		jiffies_to_clock_t(iowait),
 		jiffies_to_clock_t(irq),
 		jiffies_to_clock_t(softirq));
-	for (i = 0; i < NR_CPUS; i++){
-		if (!cpu_online(i)) continue;
+	for_each_online_cpu(i) {
 		seq_printf(p, "cpu%d %u %u %u %u %u %u %u\n",
 			i,
 			jiffies_to_clock_t(kstat_cpu(i).cpustat.user),

kernel/fork.c

@@ -60,10 +60,9 @@ int nr_processes(void)
 	int cpu;
 	int total = 0;
 
-	for (cpu = 0; cpu < NR_CPUS; cpu++) {
-		if (cpu_online(cpu))
-			total += per_cpu(process_counts, cpu);
-	}
+	for_each_cpu(cpu)
+		total += per_cpu(process_counts, cpu);
+
 	return total;
 }
 

kernel/sched.c

@@ -902,11 +902,9 @@ unsigned long nr_uninterruptible(void)
 {
 	unsigned long i, sum = 0;
 
-	for (i = 0; i < NR_CPUS; i++) {
-		if (!cpu_online(i))
-			continue;
+	for_each_cpu(i)
 		sum += cpu_rq(i)->nr_uninterruptible;
-	}
+
 	return sum;
 }
 
@@ -914,11 +912,9 @@ unsigned long nr_context_switches(void)
 {
 	unsigned long i, sum = 0;
 
-	for (i = 0; i < NR_CPUS; i++) {
-		if (!cpu_online(i))
-			continue;
+	for_each_cpu(i)
 		sum += cpu_rq(i)->nr_switches;
-	}
+
 	return sum;
 }
 
@@ -926,11 +922,9 @@ unsigned long nr_iowait(void)
 {
 	unsigned long i, sum = 0;
 
-	for (i = 0; i < NR_CPUS; ++i) {
-		if (!cpu_online(i))
-			continue;
+	for_each_cpu(i)
 		sum += atomic_read(&cpu_rq(i)->nr_iowait);
-	}
+
 	return sum;
 }
 

kernel/timer.c

@@ -332,10 +332,7 @@ int del_timer_sync(struct timer_list *timer)
 del_again:
 	ret += del_timer(timer);
 
-	for (i = 0; i < NR_CPUS; i++) {
-		if (!cpu_online(i))
-			continue;
-
+	for_each_cpu(i) {
 		base = &per_cpu(tvec_bases, i);
 		if (base->running_timer == timer) {
 			while (base->running_timer == timer) {

kernel/workqueue.c

@@ -366,9 +366,7 @@ int current_is_keventd(void)
 
 	BUG_ON(!keventd_wq);
 
-	for (cpu = 0; cpu < NR_CPUS; cpu++) {
-		if (!cpu_online(cpu))
-			continue;
+	for_each_cpu(cpu) {
 		cwq = keventd_wq->cpu_wq + cpu;
 		if (current == cwq->thread)
 			return 1;

mm/page_alloc.c

@@ -868,14 +868,14 @@ void __get_page_state(struct page_state *ret, int nr)
 	while (cpu < NR_CPUS) {
 		unsigned long *in, *out, off;
 
-		if (!cpu_online(cpu)) {
+		if (!cpu_possible(cpu)) {
 			cpu++;
 			continue;
 		}
 
 		in = (unsigned long *)&per_cpu(page_states, cpu);
 		cpu++;
-		if (cpu < NR_CPUS && cpu_online(cpu))
+		if (cpu < NR_CPUS && cpu_possible(cpu))
 			prefetch(&per_cpu(page_states, cpu));
 		out = (unsigned long *)ret;
 		for (off = 0; off < nr; off++)

net/ipv4/route.c

@@ -2703,12 +2703,9 @@ static int ip_rt_acct_read(char *buffer, char **start, off_t offset,
 		memcpy(dst, src, length);
 
 		/* Add the other cpus in, one int at a time */
-		for (i = 1; i < NR_CPUS; i++) {
+		for_each_cpu(i) {
 			unsigned int j;
 
-			if (!cpu_online(i))
-				continue;
-
 			src = ((u32 *) IP_RT_ACCT_CPU(i)) + offset;
 
 			for (j = 0; j < length/4; j++)