[PATCH] suspend/resume SMP support
Using CPU hotplug to support suspend/resume SMP. Both S3 and S4 use
disable/enable_nonboot_cpus API. The S4 part is based on Pavel's original S4
SMP patch.
Signed-off-by: Li Shaohua<shaohua.li@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/kernel/power/smp.c b/kernel/power/smp.c
index 457c230..bbe2307 100644
--- a/kernel/power/smp.c
+++ b/kernel/power/smp.c
@@ -13,73 +13,52 @@
#include <linux/interrupt.h>
#include <linux/suspend.h>
#include <linux/module.h>
+#include <linux/cpu.h>
#include <asm/atomic.h>
#include <asm/tlbflush.h>
-static atomic_t cpu_counter, freeze;
-
-
-static void smp_pause(void * data)
-{
- struct saved_context ctxt;
- __save_processor_state(&ctxt);
- printk("Sleeping in:\n");
- dump_stack();
- atomic_inc(&cpu_counter);
- while (atomic_read(&freeze)) {
- /* FIXME: restore takes place at random piece inside this.
- This should probably be written in assembly, and
- preserve general-purpose registers, too
-
- What about stack? We may need to move to new stack here.
-
- This should better be ran with interrupts disabled.
- */
- cpu_relax();
- barrier();
- }
- atomic_dec(&cpu_counter);
- __restore_processor_state(&ctxt);
-}
-
-static cpumask_t oldmask;
+/* This is protected by pm_sem semaphore */
+static cpumask_t frozen_cpus;
void disable_nonboot_cpus(void)
{
- oldmask = current->cpus_allowed;
- set_cpus_allowed(current, cpumask_of_cpu(0));
- printk("Freezing CPUs (at %d)", raw_smp_processor_id());
- current->state = TASK_INTERRUPTIBLE;
- schedule_timeout(HZ);
- printk("...");
- BUG_ON(raw_smp_processor_id() != 0);
+ int cpu, error;
- /* FIXME: for this to work, all the CPUs must be running
- * "idle" thread (or we deadlock). Is that guaranteed? */
-
- atomic_set(&cpu_counter, 0);
- atomic_set(&freeze, 1);
- smp_call_function(smp_pause, NULL, 0, 0);
- while (atomic_read(&cpu_counter) < (num_online_cpus() - 1)) {
- cpu_relax();
- barrier();
+ error = 0;
+ cpus_clear(frozen_cpus);
+ printk("Freezing cpus ...\n");
+ for_each_online_cpu(cpu) {
+ if (cpu == 0)
+ continue;
+ error = cpu_down(cpu);
+ if (!error) {
+ cpu_set(cpu, frozen_cpus);
+ printk("CPU%d is down\n", cpu);
+ continue;
+ }
+ printk("Error taking cpu %d down: %d\n", cpu, error);
}
- printk("ok\n");
+ BUG_ON(smp_processor_id() != 0);
+ if (error)
+ panic("cpus not sleeping");
}
void enable_nonboot_cpus(void)
{
- printk("Restarting CPUs");
- atomic_set(&freeze, 0);
- while (atomic_read(&cpu_counter)) {
- cpu_relax();
- barrier();
+ int cpu, error;
+
+ printk("Thawing cpus ...\n");
+ for_each_cpu_mask(cpu, frozen_cpus) {
+ error = smp_prepare_cpu(cpu);
+ if (!error)
+ error = cpu_up(cpu);
+ if (!error) {
+ printk("CPU%d is up\n", cpu);
+ continue;
+ }
+ printk("Error taking cpu %d up: %d\n", cpu, error);
+ panic("Not enough cpus");
}
- printk("...");
- set_cpus_allowed(current, oldmask);
- schedule();
- printk("ok\n");
-
+ cpus_clear(frozen_cpus);
}
-