[PATCH 2/2] Use for_each_cpu() Where It's Meant To Be

From: Rusty Russell
Date: Tue Dec 30 2003 - 20:33:35 EST

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Please apply.

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).

Name: Use for_each_cpu() where cpu_online() is incorrectly used.
Author: Rusty Russell
Status: Booted on 2.6.0
Depends: Hotcpu/cpu_iterator.patch.gz

D: Some places use cpu_online() where they should be using cpu_possible,
D: most commonly for tallying statistics. This makes no difference without
D: hotplug CPU.
D:
D: Use the for_each_cpu() macro in those places, providing good
D: examples (and making the external hotplug CPU patch smaller).

diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .908-linux-2.6.0-test7-bk3/fs/buffer.c .908-linux-2.6.0-test7-bk3.updated/fs/buffer.c
--- .908-linux-2.6.0-test7-bk3/fs/buffer.c 2003-10-09 18:02:57.000000000 +1000
+++ .908-linux-2.6.0-test7-bk3.updated/fs/buffer.c 2003-10-13 08:45:09.000000000 +1000
@@ -2944,10 +2944,8 @@ 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);
}

diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .908-linux-2.6.0-test7-bk3/fs/proc/proc_misc.c .908-linux-2.6.0-test7-bk3.updated/fs/proc/proc_misc.c
--- .908-linux-2.6.0-test7-bk3/fs/proc/proc_misc.c 2003-09-29 10:25:53.000000000 +1000
+++ .908-linux-2.6.0-test7-bk3.updated/fs/proc/proc_misc.c 2003-10-13 08:45:09.000000000 +1000
@@ -378,10 +378,9 @@ int show_stat(struct seq_file *p, void *
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 *
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),
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .908-linux-2.6.0-test7-bk3/kernel/fork.c .908-linux-2.6.0-test7-bk3.updated/kernel/fork.c
--- .908-linux-2.6.0-test7-bk3/kernel/fork.c 2003-10-12 11:04:17.000000000 +1000
+++ .908-linux-2.6.0-test7-bk3.updated/kernel/fork.c 2003-10-13 08:45:09.000000000 +1000
@@ -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;
}

diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .908-linux-2.6.0-test7-bk3/kernel/sched.c .908-linux-2.6.0-test7-bk3.updated/kernel/sched.c
--- .908-linux-2.6.0-test7-bk3/kernel/sched.c 2003-10-09 18:03:02.000000000 +1000
+++ .908-linux-2.6.0-test7-bk3.updated/kernel/sched.c 2003-10-13 08:45:09.000000000 +1000
@@ -829,11 +829,9 @@ 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;
}

@@ -841,11 +839,9 @@ 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;
}

@@ -853,11 +849,9 @@ 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;
}

diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .908-linux-2.6.0-test7-bk3/kernel/workqueue.c .908-linux-2.6.0-test7-bk3.updated/kernel/workqueue.c
--- .908-linux-2.6.0-test7-bk3/kernel/workqueue.c 2003-09-22 10:27:38.000000000 +1000
+++ .908-linux-2.6.0-test7-bk3.updated/kernel/workqueue.c 2003-10-13 08:45:09.000000000 +1000
@@ -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;
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .908-linux-2.6.0-test7-bk3/mm/page_alloc.c .908-linux-2.6.0-test7-bk3.updated/mm/page_alloc.c
--- .908-linux-2.6.0-test7-bk3/mm/page_alloc.c 2003-10-09 18:03:02.000000000 +1000
+++ .908-linux-2.6.0-test7-bk3.updated/mm/page_alloc.c 2003-10-13 08:49:27.000000000 +1000
@@ -867,14 +867,14 @@ void __get_page_state(struct page_state
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++)
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .908-linux-2.6.0-test7-bk3/net/ipv4/route.c .908-linux-2.6.0-test7-bk3.updated/net/ipv4/route.c
--- .908-linux-2.6.0-test7-bk3/net/ipv4/route.c 2003-10-09 18:03:03.000000000 +1000
+++ .908-linux-2.6.0-test7-bk3.updated/net/ipv4/route.c 2003-10-13 08:45:09.000000000 +1000
@@ -2703,12 +2703,9 @@ static int ip_rt_acct_read(char *buffer,
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++)
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .3441-2.6.0-test9-hotcpu-i386.pre/kernel/timer.c .3441-2.6.0-test9-hotcpu-i386/kernel/timer.c
--- .3441-2.6.0-test9-hotcpu-i386.pre/kernel/timer.c 2003-10-27 13:26:01.000000000 +1100
+++ .3441-2.6.0-test9-hotcpu-i386/kernel/timer.c 2003-10-27 13:26:02.000000000 +1100
@@ -332,10 +332,7 @@ int del_timer_sync(struct timer_list *ti
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) {

--
Anyone who quotes me in their sig is an idiot. -- Rusty Russell.
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Next message: Rusty Russell: "[PATCH 1/2] Make for_each_cpu() Iterator More Friendly"
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