[PATCH] swsusp: preparation for smp support & fix device suspending

It fixes levels for calling driver model, puts devices into sleep before
powering down (so that emergency parking does not happen), and actually
introduces SMP support, but its disabled for now.  Plus noone should try to
freeze_processes() when thats not implemented, we now BUG()s -- we do not
want Heisenbugs.

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 98 insertions, 7 deletions

diff --git a/kernel/power/Makefile b/kernel/power/Makefile
index d00edd15c0fd..079dd4d678ce 100644
--- a/kernel/power/Makefile
+++ b/kernel/power/Makefile
@@ -1,4 +1,5 @@
 obj-y				:= main.o process.o console.o pm.o
+obj-$(CONFIG_SMP)		+= smp.o
 obj-$(CONFIG_SOFTWARE_SUSPEND)	+= swsusp.o
 obj-$(CONFIG_PM_DISK)		+= disk.o pmdisk.o
 
diff --git a/kernel/power/smp.c b/kernel/power/smp.c
new file mode 100644
index 000000000000..cda77cdfb8c1
--- /dev/null
+++ b/kernel/power/smp.c
@@ -0,0 +1,85 @@
+/*
+ * drivers/power/smp.c - Functions for stopping other CPUs.
+ *
+ * Copyright 2004 Pavel Machek <pavel@suse.cz>
+ * Copyright (C) 2002-2003 Nigel Cunningham <ncunningham@clear.net.nz>
+ *
+ * This file is released under the GPLv2.
+ */
+
+#undef DEBUG
+
+#include <linux/smp_lock.h>
+#include <linux/interrupt.h>
+#include <linux/suspend.h>
+#include <linux/module.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);
+}
+
+cpumask_t oldmask;
+
+void disable_nonboot_cpus(void)
+{
+	printk("Freezing CPUs (at %d)", smp_processor_id());
+	oldmask = current->cpus_allowed;
+	set_cpus_allowed(current, cpumask_of_cpu(0));
+	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();
+	}
+	printk("ok\n");
+}
+
+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");
+
+}
+
+
diff --git a/kernel/power/swsusp.c b/kernel/power/swsusp.c
index ff8fdbc21a45..6cfe0551088d 100644
--- a/kernel/power/swsusp.c
+++ b/kernel/power/swsusp.c
@@ -696,6 +696,7 @@ static void suspend_power_down(void)
 	else
 #endif
 	{
+		device_suspend(3);
 		device_shutdown();
 		machine_power_off();
 	}
@@ -716,7 +717,7 @@ asmlinkage void do_magic_resume_1(void)
 	mb();
 	spin_lock_irq(&suspend_pagedir_lock);	/* Done to disable interrupts */ 
 
-	device_power_down(4);
+	device_power_down(3);
 	PRINTK( "Waiting for DMAs to settle down...\n");
 	mdelay(1000);	/* We do not want some readahead with DMA to corrupt our memory, right?
 			   Do it with disabled interrupts for best effect. That way, if some
@@ -785,7 +786,7 @@ asmlinkage void do_magic_suspend_2(void)
 {
 	int is_problem;
 	read_swapfiles();
-	device_power_down(4);
+	device_power_down(3);
 	is_problem = suspend_prepare_image();
 	device_power_up();
 	spin_unlock_irq(&suspend_pagedir_lock);
@@ -802,7 +803,6 @@ asmlinkage void do_magic_suspend_2(void)
 	barrier();
 	mb();
 	spin_lock_irq(&suspend_pagedir_lock);	/* Done to disable interrupts */ 
-	mdelay(1000);
 
 	free_pages((unsigned long) pagedir_nosave, pagedir_order);
 	spin_unlock_irq(&suspend_pagedir_lock);
@@ -839,9 +839,10 @@ int software_suspend(void)
                    need half of memory free. */
 
 		free_some_memory();
-		
-		/* Save state of all device drivers, and stop them. */		   
-		if ((res = device_suspend(4))==0)
+		disable_nonboot_cpus();
+		/* Save state of all device drivers, and stop them. */
+		printk("Suspending devices... ");
+		if ((res = device_suspend(3))==0) {
 			/* If stopping device drivers worked, we proceed basically into
 			 * suspend_save_image.
 			 *
@@ -852,7 +853,9 @@ int software_suspend(void)
 			 * using normal kernel mechanism.
 			 */
 			do_magic(0);
+		}
 		thaw_processes();
+		enable_nonboot_cpus();
 	} else
 		res = -EBUSY;
 	software_suspend_enabled = 1;
@@ -1192,7 +1195,9 @@ static int __init software_resume(void)
 	printk( "resuming from %s\n", resume_file);
 	if (read_suspend_image(resume_file, 0))
 		goto read_failure;
-	device_suspend(4);
+	/* FIXME: Should we stop processes here, just to be safer? */
+	disable_nonboot_cpus();
+	device_suspend(3);
 	do_magic(1);
 	panic("This never returns");