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cpumask: convert kernel/cpu.c 

Impact: Reduce kernel stack and memory usage, use new cpumask API.

Use cpumask_var_t for take_cpu_down() stack var, and frozen_cpus.

Note that notify_cpu_starting() can be called before core_initcall
allocates frozen_cpus, but the NULL check is optimized out by gcc for
the CONFIG_CPUMASK_OFFSTACK=n case.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2009-01-01 10:12:28 +10:30
parent c309b917ca
commit e0b582ec56
1 changed files with 29 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

48
kernel/cpu.c
View File

@ -194,7 +194,7 @@ static int __ref take_cpu_down(void *_param)
static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
{
int err, nr_calls = 0;
cpumask_t old_allowed, tmp;
cpumask_var_t old_allowed;
void *hcpu = (void *)(long)cpu;
unsigned long mod = tasks_frozen ? CPU_TASKS_FROZEN : 0;
struct take_cpu_down_param tcd_param = {
@ -208,6 +208,9 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
if (!cpu_online(cpu))
return -EINVAL;
if (!alloc_cpumask_var(&old_allowed, GFP_KERNEL))
return -ENOMEM;
cpu_hotplug_begin();
err = __raw_notifier_call_chain(&cpu_chain, CPU_DOWN_PREPARE | mod,
hcpu, -1, &nr_calls);
@ -222,13 +225,11 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
}
/* Ensure that we are not runnable on dying cpu */
old_allowed = current->cpus_allowed;
cpus_setall(tmp);
cpu_clear(cpu, tmp);
set_cpus_allowed_ptr(current, &tmp);
tmp = cpumask_of_cpu(cpu);
cpumask_copy(old_allowed, &current->cpus_allowed);
set_cpus_allowed_ptr(current,
cpumask_of(cpumask_any_but(cpu_online_mask, cpu)));
err = __stop_machine(take_cpu_down, &tcd_param, &tmp);
err = __stop_machine(take_cpu_down, &tcd_param, cpumask_of(cpu));
if (err) {
/* CPU didn't die: tell everyone. Can't complain. */
if (raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod,
@ -254,7 +255,7 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
check_for_tasks(cpu);
out_allowed:
set_cpus_allowed_ptr(current, &old_allowed);
set_cpus_allowed_ptr(current, old_allowed);
out_release:
cpu_hotplug_done();
if (!err) {
@ -262,6 +263,7 @@ out_release:
hcpu) == NOTIFY_BAD)
BUG();
}
free_cpumask_var(old_allowed);
return err;
}
@ -280,7 +282,7 @@ int __ref cpu_down(unsigned int cpu)
/*
* Make sure the all cpus did the reschedule and are not
* using stale version of the cpu_active_map.
* using stale version of the cpu_active_mask.
* This is not strictly necessary becuase stop_machine()
* that we run down the line already provides the required
* synchronization. But it's really a side effect and we do not
@ -344,7 +346,7 @@ out_notify:
int __cpuinit cpu_up(unsigned int cpu)
{
int err = 0;
if (!cpu_isset(cpu, cpu_possible_map)) {
if (!cpu_possible(cpu)) {
printk(KERN_ERR "can't online cpu %d because it is not "
"configured as may-hotadd at boot time\n", cpu);
#if defined(CONFIG_IA64) || defined(CONFIG_X86_64)
@ -369,25 +371,25 @@ out:
}
#ifdef CONFIG_PM_SLEEP_SMP
static cpumask_t frozen_cpus;
static cpumask_var_t frozen_cpus;
int disable_nonboot_cpus(void)
{
int cpu, first_cpu, error = 0;
cpu_maps_update_begin();
first_cpu = first_cpu(cpu_online_map);
first_cpu = cpumask_first(cpu_online_mask);
/* We take down all of the non-boot CPUs in one shot to avoid races
* with the userspace trying to use the CPU hotplug at the same time
*/
cpus_clear(frozen_cpus);
cpumask_clear(frozen_cpus);
printk("Disabling non-boot CPUs ...\n");
for_each_online_cpu(cpu) {
if (cpu == first_cpu)
continue;
error = _cpu_down(cpu, 1);
if (!error) {
cpu_set(cpu, frozen_cpus);
cpumask_set_cpu(cpu, frozen_cpus);
printk("CPU%d is down\n", cpu);
} else {
printk(KERN_ERR "Error taking CPU%d down: %d\n",
@ -413,11 +415,11 @@ void __ref enable_nonboot_cpus(void)
/* Allow everyone to use the CPU hotplug again */
cpu_maps_update_begin();
cpu_hotplug_disabled = 0;
if (cpus_empty(frozen_cpus))
if (cpumask_empty(frozen_cpus))
goto out;
printk("Enabling non-boot CPUs ...\n");
for_each_cpu_mask_nr(cpu, frozen_cpus) {
for_each_cpu(cpu, frozen_cpus) {
error = _cpu_up(cpu, 1);
if (!error) {
printk("CPU%d is up\n", cpu);
@ -425,10 +427,18 @@ void __ref enable_nonboot_cpus(void)
}
printk(KERN_WARNING "Error taking CPU%d up: %d\n", cpu, error);
}
cpus_clear(frozen_cpus);
cpumask_clear(frozen_cpus);
out:
cpu_maps_update_done();
}
static int alloc_frozen_cpus(void)
{
if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO))
return -ENOMEM;
return 0;
}
core_initcall(alloc_frozen_cpus);
#endif /* CONFIG_PM_SLEEP_SMP */
/**
@ -444,7 +454,7 @@ void __cpuinit notify_cpu_starting(unsigned int cpu)
unsigned long val = CPU_STARTING;
#ifdef CONFIG_PM_SLEEP_SMP
if (cpu_isset(cpu, frozen_cpus))
if (frozen_cpus != NULL && cpumask_test_cpu(cpu, frozen_cpus))
val = CPU_STARTING_FROZEN;
#endif /* CONFIG_PM_SLEEP_SMP */
raw_notifier_call_chain(&cpu_chain, val, (void *)(long)cpu);
@ -456,7 +466,7 @@ void __cpuinit notify_cpu_starting(unsigned int cpu)
* cpu_bit_bitmap[] is a special, "compressed" data structure that
* represents all NR_CPUS bits binary values of 1<<nr.
*
* It is used by cpumask_of_cpu() to get a constant address to a CPU
* It is used by cpumask_of() to get a constant address to a CPU
* mask value that has a single bit set only.
*/