[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>

1 files changed, 34 insertions, 55 deletions

diff --git a/kernel/power/smp.c b/kernel/power/smp.c
index 457c2302ed42..bbe23079c62c 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);
-
-        /* FIXME: for this to work, all the CPUs must be running
-         * "idle" thread (or we deadlock). Is that guaranteed? */
+        int cpu, error;
 
-        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();
-        }
-        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);
 }
 
-