PM: ACPI and APM must not be enabled at the same time

ACPI and APM used "pm_active" to guarantee that
they would not be simultaneously active.

But pm_active was recently moved under CONFIG_PM_LEGACY,
so that without CONFIG_PM_LEGACY, pm_active became a NOP --
allowing ACPI and APM to both be simultaneously enabled.
This caused unpredictable results, including boot hangs.

Further, the code under CONFIG_PM_LEGACY is scheduled
for removal.

So replace pm_active with pm_flags.
pm_flags depends only on CONFIG_PM,
which is present for both CONFIG_APM and CONFIG_ACPI.

http://bugzilla.kernel.org/show_bug.cgi?id=9194

Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

6 files changed, 17 insertions, 22 deletions

diff --git a/arch/x86/kernel/apm_32.c b/arch/x86/kernel/apm_32.c
index 17089a041028..af045ca0f653 100644
--- a/arch/x86/kernel/apm_32.c
+++ b/arch/x86/kernel/apm_32.c
@@ -2256,14 +2256,12 @@ static int __init apm_init(void)
                 apm_info.disabled = 1;
                 return -ENODEV;
         }
-        if (PM_IS_ACTIVE()) {
+        if (pm_flags & PM_ACPI) {
                 printk(KERN_NOTICE "apm: overridden by ACPI.\n");
                 apm_info.disabled = 1;
                 return -ENODEV;
         }
-#ifdef CONFIG_PM_LEGACY
-        pm_active = 1;
-#endif
+        pm_flags |= PM_APM;
 
         /*
          * Set up a segment that references the real mode segment 0x40
@@ -2366,9 +2364,7 @@ static void __exit apm_exit(void)
                 kthread_stop(kapmd_task);
                 kapmd_task = NULL;
         }
-#ifdef CONFIG_PM_LEGACY
-        pm_active = 0;
-#endif
+        pm_flags &= ~PM_APM;
 }
 
 module_init(apm_init);
diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index 49d432d0a12c..d7a115c362d1 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -29,7 +29,6 @@
 #include <linux/list.h>
 #include <linux/sched.h>
 #include <linux/pm.h>
-#include <linux/pm_legacy.h>
 #include <linux/device.h>
 #include <linux/proc_fs.h>
 #ifdef CONFIG_X86
@@ -764,16 +763,14 @@ static int __init acpi_init(void)
         result = acpi_bus_init();
 
         if (!result) {
-#ifdef CONFIG_PM_LEGACY
-                if (!PM_IS_ACTIVE())
-                        pm_active = 1;
+                if (!(pm_flags & PM_APM))
+                        pm_flags |= PM_ACPI;
                 else {
                         printk(KERN_INFO PREFIX
                                "APM is already active, exiting\n");
                         disable_acpi();
                         result = -ENODEV;
                 }
-#endif
         } else
                 disable_acpi();
 
diff --git a/include/linux/pm.h b/include/linux/pm.h
index 09a309b7b5d2..b78e0295adf4 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -246,6 +246,15 @@ static inline int call_platform_enable_wakeup(struct device *dev, int is_on)
                 device_set_wakeup_enable(dev,val); \
         } while(0)
 
+/*
+ * Global Power Management flags
+ * Used to keep APM and ACPI from both being active
+ */
+extern unsigned int     pm_flags;
+
+#define PM_APM  1
+#define PM_ACPI 2
+
 #endif /* __KERNEL__ */
 
 #endif /* _LINUX_PM_H */
diff --git a/include/linux/pm_legacy.h b/include/linux/pm_legacy.h
index 514729a44688..446f4f42b952 100644
--- a/include/linux/pm_legacy.h
+++ b/include/linux/pm_legacy.h
@@ -4,10 +4,6 @@
 
 #ifdef CONFIG_PM_LEGACY
 
-extern int pm_active;
-
-#define PM_IS_ACTIVE() (pm_active != 0)
-
 /*
  * Register a device with power management
  */
@@ -21,8 +17,6 @@ int __deprecated pm_send_all(pm_request_t rqst, void *data);
 
 #else /* CONFIG_PM_LEGACY */
 
-#define PM_IS_ACTIVE() 0
-
 static inline struct pm_dev *pm_register(pm_dev_t type,
                                          unsigned long id,
                                          pm_callback callback)
diff --git a/kernel/power/main.c b/kernel/power/main.c
index 3cdf95b1dc92..f71c9504a5c5 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -28,6 +28,9 @@ BLOCKING_NOTIFIER_HEAD(pm_chain_head);
 
 DEFINE_MUTEX(pm_mutex);
 
+unsigned int pm_flags;
+EXPORT_SYMBOL(pm_flags);
+
 #ifdef CONFIG_SUSPEND
 
 /* This is just an arbitrary number */
diff --git a/kernel/power/pm.c b/kernel/power/pm.c
index c50d15266c10..60c73fa670d5 100644
--- a/kernel/power/pm.c
+++ b/kernel/power/pm.c
@@ -27,8 +27,6 @@
 #include <linux/interrupt.h>
 #include <linux/mutex.h>
 
-int pm_active;
-
 /*
  *      Locking notes:
  *              pm_devs_lock can be a semaphore providing pm ops are not called
@@ -204,6 +202,4 @@ int pm_send_all(pm_request_t rqst, void *data)
 
 EXPORT_SYMBOL(pm_register);
 EXPORT_SYMBOL(pm_send_all);
-EXPORT_SYMBOL(pm_active);
-