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Subject[PATCH 6/6]suspend/resume SMP support
From
Date
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>
---
linux-2.6.11-root/drivers/acpi/Kconfig | 2
linux-2.6.11-root/include/linux/suspend.h | 2
linux-2.6.11-root/kernel/power/Kconfig | 2
linux-2.6.11-root/kernel/power/disk.c | 36 ++++++-----
linux-2.6.11-root/kernel/power/main.c | 16 +++--
linux-2.6.11-root/kernel/power/smp.c | 91 +++++++++++-------------------
linux-2.6.11-root/kernel/power/swsusp.c | 2
7 files changed, 69 insertions(+), 82 deletions(-)
diff -puN drivers/acpi/Kconfig~smp_sleep drivers/acpi/Kconfig
--- linux-2.6.11/drivers/acpi/Kconfig~smp_sleep 2005-04-12 11:11:14.884685080 +0800
+++ linux-2.6.11-root/drivers/acpi/Kconfig 2005-04-12 11:11:14.898682952 +0800
@@ -57,7 +57,7 @@ if ACPI_INTERPRETER

config ACPI_SLEEP
bool "Sleep States (EXPERIMENTAL)"
- depends on X86
+ depends on X86 && (!SMP || HOTPLUG_CPU)
depends on EXPERIMENTAL
default y
---help---
diff -puN include/linux/suspend.h~smp_sleep include/linux/suspend.h
--- linux-2.6.11/include/linux/suspend.h~smp_sleep 2005-04-12 11:11:14.885684928 +0800
+++ linux-2.6.11-root/include/linux/suspend.h 2005-04-12 11:11:14.898682952 +0800
@@ -58,7 +58,7 @@ static inline int software_suspend(void)
}
#endif

-#ifdef CONFIG_SMP
+#ifdef CONFIG_HOTPLUG_CPU
extern void disable_nonboot_cpus(void);
extern void enable_nonboot_cpus(void);
#else
diff -puN kernel/power/disk.c~smp_sleep kernel/power/disk.c
--- linux-2.6.11/kernel/power/disk.c~smp_sleep 2005-04-12 11:11:14.887684624 +0800
+++ linux-2.6.11-root/kernel/power/disk.c 2005-04-12 11:11:14.899682800 +0800
@@ -117,8 +117,8 @@ static void finish(void)
{
device_resume();
platform_finish();
- enable_nonboot_cpus();
thaw_processes();
+ enable_nonboot_cpus();
pm_restore_console();
}

@@ -131,28 +131,36 @@ static int prepare_processes(void)

sys_sync();

+ disable_nonboot_cpus();
+
if (freeze_processes()) {
error = -EBUSY;
- return error;
+ goto enable_cpu;
}

if (pm_disk_mode == PM_DISK_PLATFORM) {
if (pm_ops && pm_ops->prepare) {
if ((error = pm_ops->prepare(PM_SUSPEND_DISK)))
- return error;
+ goto thaw;
}
}

/* Free memory before shutting down devices. */
free_some_memory();
-
return 0;
+thaw:
+ thaw_processes();
+enable_cpu:
+ enable_nonboot_cpus();
+ pm_restore_console();
+ return error;
}

static void unprepare_processes(void)
{
- enable_nonboot_cpus();
+ platform_finish();
thaw_processes();
+ enable_nonboot_cpus();
pm_restore_console();
}

@@ -160,15 +168,9 @@ static int prepare_devices(void)
{
int error;

- disable_nonboot_cpus();
- if ((error = device_suspend(PMSG_FREEZE))) {
+ if ((error = device_suspend(PMSG_FREEZE)))
printk("Some devices failed to suspend\n");
- platform_finish();
- enable_nonboot_cpus();
- return error;
- }
-
- return 0;
+ return error;
}

/**
@@ -185,9 +187,9 @@ int pm_suspend_disk(void)
int error;

error = prepare_processes();
- if (!error) {
- error = prepare_devices();
- }
+ if (error)
+ return error;
+ error = prepare_devices();

if (error) {
unprepare_processes();
@@ -250,7 +252,7 @@ static int software_resume(void)

if ((error = prepare_processes())) {
swsusp_close();
- goto Cleanup;
+ goto Done;
}

pr_debug("PM: Reading swsusp image.\n");
diff -puN kernel/power/Kconfig~smp_sleep kernel/power/Kconfig
--- linux-2.6.11/kernel/power/Kconfig~smp_sleep 2005-04-12 11:11:14.888684472 +0800
+++ linux-2.6.11-root/kernel/power/Kconfig 2005-04-12 11:11:14.899682800 +0800
@@ -28,7 +28,7 @@ config PM_DEBUG

config SOFTWARE_SUSPEND
bool "Software Suspend (EXPERIMENTAL)"
- depends on EXPERIMENTAL && PM && SWAP
+ depends on EXPERIMENTAL && PM && SWAP && (HOTPLUG_CPU || !SMP)
---help---
Enable the possibility of suspending the machine.
It doesn't need APM.
diff -puN kernel/power/main.c~smp_sleep kernel/power/main.c
--- linux-2.6.11/kernel/power/main.c~smp_sleep 2005-04-12 11:11:14.890684168 +0800
+++ linux-2.6.11-root/kernel/power/main.c 2005-04-12 11:11:14.899682800 +0800
@@ -59,6 +59,13 @@ static int suspend_prepare(suspend_state

pm_prepare_console();

+ disable_nonboot_cpus();
+
+ if (num_online_cpus() != 1) {
+ error = -EPERM;
+ goto Enable_cpu;
+ }
+
if (freeze_processes()) {
error = -EAGAIN;
goto Thaw;
@@ -89,6 +96,8 @@ static int suspend_prepare(suspend_state
pm_ops->finish(state);
Thaw:
thaw_processes();
+ Enable_cpu:
+ enable_nonboot_cpus();
pm_restore_console();
return error;
}
@@ -127,6 +136,7 @@ static void suspend_finish(suspend_state
if (pm_ops && pm_ops->finish)
pm_ops->finish(state);
thaw_processes();
+ enable_nonboot_cpus();
pm_restore_console();
}

@@ -164,12 +174,6 @@ static int enter_state(suspend_state_t s
goto Unlock;
}

- /* Suspend is hard to get right on SMP. */
- if (num_online_cpus() != 1) {
- error = -EPERM;
- goto Unlock;
- }
-
pr_debug("PM: Preparing system for suspend\n");
if ((error = suspend_prepare(state)))
goto Unlock;
diff -puN kernel/power/smp.c~smp_sleep kernel/power/smp.c
--- linux-2.6.11/kernel/power/smp.c~smp_sleep 2005-04-12 11:11:14.891684016 +0800
+++ linux-2.6.11-root/kernel/power/smp.c 2005-04-12 11:11:14.899682800 +0800
@@ -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)", _smp_processor_id());
- current->state = TASK_INTERRUPTIBLE;
- schedule_timeout(HZ);
- printk("...");
- BUG_ON(_smp_processor_id() != 0);
-
- /* 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();
+ int cpu, error;
+
+ 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();
- }
- printk("...");
- set_cpus_allowed(current, oldmask);
- schedule();
- printk("ok\n");
+ 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");
+ }
+ cpus_clear(frozen_cpus);
}

-
diff -puN kernel/power/swsusp.c~smp_sleep kernel/power/swsusp.c
--- linux-2.6.11/kernel/power/swsusp.c~smp_sleep 2005-04-12 11:11:14.892683864 +0800
+++ linux-2.6.11-root/kernel/power/swsusp.c 2005-04-12 11:11:14.900682648 +0800
@@ -1194,8 +1194,10 @@ static const char * sanity_check(void)
return "version";
if (strcmp(swsusp_info.uts.machine,system_utsname.machine))
return "machine";
+#if 0
if(swsusp_info.cpus != num_online_cpus())
return "number of cpus";
+#endif
return NULL;
}

_

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