ACPI: convert acpi_device_lock spinlock to mutex

Convert acpi_device_lock to a mutex to avoid
a potential race upon access to /proc/acpi/wakeup

Delete the lock entirely in wakeup.c
since it is not necessary (and can not sleep)

Found-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 7 insertions, 23 deletions

diff --git a/drivers/acpi/wakeup.c b/drivers/acpi/wakeup.c
index 5aee8c26cc9f..88725dcdf8bc 100644
--- a/drivers/acpi/wakeup.c
+++ b/drivers/acpi/wakeup.c
@@ -12,12 +12,14 @@
 #include "internal.h"
 #include "sleep.h"
 
+/*
+ * We didn't lock acpi_device_lock in the file, because it invokes oops in
+ * suspend/resume and isn't really required as this is called in S-state. At
+ * that time, there is no device hotplug
+ **/
 #define _COMPONENT		ACPI_SYSTEM_COMPONENT
 ACPI_MODULE_NAME("wakeup_devices")
 
-extern struct list_head acpi_wakeup_device_list;
-extern spinlock_t acpi_device_lock;
-
 /**
  * acpi_enable_wakeup_device_prep - prepare wakeup devices
  *	@sleep_state:	ACPI state
@@ -29,7 +31,6 @@ void acpi_enable_wakeup_device_prep(u8 sleep_state)
 {
 	struct list_head *node, *next;
 
-	spin_lock(&acpi_device_lock);
 	list_for_each_safe(node, next, &acpi_wakeup_device_list) {
 		struct acpi_device *dev = container_of(node,
 						       struct acpi_device,
@@ -40,11 +41,8 @@ void acpi_enable_wakeup_device_prep(u8 sleep_state)
 		    (sleep_state > (u32) dev->wakeup.sleep_state))
 			continue;
 
-		spin_unlock(&acpi_device_lock);
 		acpi_enable_wakeup_device_power(dev, sleep_state);
-		spin_lock(&acpi_device_lock);
 	}
-	spin_unlock(&acpi_device_lock);
 }
 
 /**
@@ -60,7 +58,6 @@ void acpi_enable_wakeup_device(u8 sleep_state)
 	 * Caution: this routine must be invoked when interrupt is disabled 
 	 * Refer ACPI2.0: P212
 	 */
-	spin_lock(&acpi_device_lock);
 	list_for_each_safe(node, next, &acpi_wakeup_device_list) {
 		struct acpi_device *dev =
 			container_of(node, struct acpi_device, wakeup_list);
@@ -74,22 +71,17 @@ void acpi_enable_wakeup_device(u8 sleep_state)
 		if ((!dev->wakeup.state.enabled && !dev->wakeup.flags.prepared)
 		    || sleep_state > (u32) dev->wakeup.sleep_state) {
 			if (dev->wakeup.flags.run_wake) {
-				spin_unlock(&acpi_device_lock);
 				/* set_gpe_type will disable GPE, leave it like that */
 				acpi_set_gpe_type(dev->wakeup.gpe_device,
 						  dev->wakeup.gpe_number,
 						  ACPI_GPE_TYPE_RUNTIME);
-				spin_lock(&acpi_device_lock);
 			}
 			continue;
 		}
-		spin_unlock(&acpi_device_lock);
 		if (!dev->wakeup.flags.run_wake)
 			acpi_enable_gpe(dev->wakeup.gpe_device,
 					dev->wakeup.gpe_number);
-		spin_lock(&acpi_device_lock);
 	}
-	spin_unlock(&acpi_device_lock);
 }
 
 /**
@@ -101,7 +93,6 @@ void acpi_disable_wakeup_device(u8 sleep_state)
 {
 	struct list_head *node, *next;
 
-	spin_lock(&acpi_device_lock);
 	list_for_each_safe(node, next, &acpi_wakeup_device_list) {
 		struct acpi_device *dev =
 			container_of(node, struct acpi_device, wakeup_list);
@@ -112,19 +103,16 @@ void acpi_disable_wakeup_device(u8 sleep_state)
 		if ((!dev->wakeup.state.enabled && !dev->wakeup.flags.prepared)
 		    || sleep_state > (u32) dev->wakeup.sleep_state) {
 			if (dev->wakeup.flags.run_wake) {
-				spin_unlock(&acpi_device_lock);
 				acpi_set_gpe_type(dev->wakeup.gpe_device,
 						  dev->wakeup.gpe_number,
 						  ACPI_GPE_TYPE_WAKE_RUN);
 				/* Re-enable it, since set_gpe_type will disable it */
 				acpi_enable_gpe(dev->wakeup.gpe_device,
 						dev->wakeup.gpe_number);
-				spin_lock(&acpi_device_lock);
 			}
 			continue;
 		}
 
-		spin_unlock(&acpi_device_lock);
 		acpi_disable_wakeup_device_power(dev);
 		/* Never disable run-wake GPE */
 		if (!dev->wakeup.flags.run_wake) {
@@ -133,16 +121,14 @@ void acpi_disable_wakeup_device(u8 sleep_state)
 			acpi_clear_gpe(dev->wakeup.gpe_device,
 				       dev->wakeup.gpe_number, ACPI_NOT_ISR);
 		}
-		spin_lock(&acpi_device_lock);
 	}
-	spin_unlock(&acpi_device_lock);
 }
 
 int __init acpi_wakeup_device_init(void)
 {
 	struct list_head *node, *next;
 
-	spin_lock(&acpi_device_lock);
+	mutex_lock(&acpi_device_lock);
 	list_for_each_safe(node, next, &acpi_wakeup_device_list) {
 		struct acpi_device *dev = container_of(node,
 						       struct acpi_device,
@@ -150,15 +136,13 @@ int __init acpi_wakeup_device_init(void)
 		/* In case user doesn't load button driver */
 		if (!dev->wakeup.flags.run_wake || dev->wakeup.state.enabled)
 			continue;
-		spin_unlock(&acpi_device_lock);
 		acpi_set_gpe_type(dev->wakeup.gpe_device,
 				  dev->wakeup.gpe_number,
 				  ACPI_GPE_TYPE_WAKE_RUN);
 		acpi_enable_gpe(dev->wakeup.gpe_device,
 				dev->wakeup.gpe_number);
 		dev->wakeup.state.enabled = 1;
-		spin_lock(&acpi_device_lock);
 	}
-	spin_unlock(&acpi_device_lock);
+	mutex_unlock(&acpi_device_lock);
 	return 0;
 }