From: Bob Moore <robert.moore@xxxxxxxxx>
Certain external interfaces need to update object references
without holding the interpreter or namespace mutex objects. To
prevent race conditions, add a spinlock around the increment
and decrement of the reference counts for internal ACPI
objects. Reported by Andriy Gapon (avg@xxxxxxxxxxx).
Signed-off-by: Bob Moore <robert.moore@xxxxxxxxx>
Signed-off-by: Andriy Gapon <avg@xxxxxxxxxxx>
Signed-off-by: Lv Zheng <lv.zheng@xxxxxxxxx>
---
drivers/acpi/acpica/acglobal.h | 1 +
drivers/acpi/acpica/utdelete.c | 82 +++++++++++++++++++++++-----------------
drivers/acpi/acpica/utmutex.c | 9 ++++-
3 files changed, 57 insertions(+), 35 deletions(-)
diff --git a/drivers/acpi/acpica/acglobal.h b/drivers/acpi/acpica/acglobal.h
index 833fbc5..0716092 100644
--- a/drivers/acpi/acpica/acglobal.h
+++ b/drivers/acpi/acpica/acglobal.h
@@ -224,6 +224,7 @@ ACPI_EXTERN u8 acpi_gbl_global_lock_pending;
*/
ACPI_EXTERN acpi_spinlock acpi_gbl_gpe_lock; /* For GPE data structs and registers */
ACPI_EXTERN acpi_spinlock acpi_gbl_hardware_lock; /* For ACPI H/W except GPE registers */
+ACPI_EXTERN acpi_spinlock acpi_gbl_reference_count_lock;
/* Mutex for _OSI support */
diff --git a/drivers/acpi/acpica/utdelete.c b/drivers/acpi/acpica/utdelete.c
index fc11ad1..29b9302 100644
--- a/drivers/acpi/acpica/utdelete.c
+++ b/drivers/acpi/acpica/utdelete.c
@@ -359,19 +359,20 @@ void acpi_ut_delete_internal_object_list(union acpi_operand_object **obj_list)
* FUNCTION: acpi_ut_update_ref_count
*
* PARAMETERS: object - Object whose ref count is to be updated
- * action - What to do
+ * action - What to do (REF_INCREMENT or REF_DECREMENT)
*
- * RETURN: New ref count
+ * RETURN: None. Sets new reference count within the object
*
- * DESCRIPTION: Modify the ref count and return it.
+ * DESCRIPTION: Modify the reference count for an internal acpi object
*
******************************************************************************/
static void
acpi_ut_update_ref_count(union acpi_operand_object *object, u32 action)
{
- u16 count;
- u16 new_count;
+ u16 original_count;
+ u16 new_count = 0;
+ acpi_cpu_flags lock_flags;
ACPI_FUNCTION_NAME(ut_update_ref_count);
@@ -379,46 +380,58 @@ acpi_ut_update_ref_count(union acpi_operand_object *object, u32 action)
return;
}
- count = object->common.reference_count;
- new_count = count;
-
/*
- * Perform the reference count action (increment, decrement, force delete)
+ * Always get the reference count lock. Note: Interpreter and/or
+ * Namespace is not always locked when this function is called.
*/
+ lock_flags = acpi_os_acquire_lock(acpi_gbl_reference_count_lock);
+ original_count = object->common.reference_count;
+
+ /* Perform the reference count action (increment, decrement) */
+
switch (action) {
case REF_INCREMENT:
- new_count++;
+ new_count = original_count + 1;
object->common.reference_count = new_count;
+ acpi_os_release_lock(acpi_gbl_reference_count_lock, lock_flags);
+
+ /* The current reference count should never be zero here */
+
+ if (!original_count) {
+ ACPI_WARNING((AE_INFO,
+ "Obj %p, Reference Count was zero before increment\n",
+ object));
+ }
ACPI_DEBUG_PRINT((ACPI_DB_ALLOCATIONS,
- "Obj %p Refs=%X, [Incremented]\n",
- object, new_count));
+ "Obj %p Type %.2X Refs %.2X [Incremented]\n",
+ object, object->common.type, new_count));
break;
case REF_DECREMENT:
- if (count < 1) {
- ACPI_DEBUG_PRINT((ACPI_DB_ALLOCATIONS,
- "Obj %p Refs=%X, can't decrement! (Set to 0)\n",
- object, new_count));
-
- new_count = 0;
- } else {
- new_count--;
+ /* The current reference count must be non-zero */
- ACPI_DEBUG_PRINT((ACPI_DB_ALLOCATIONS,
- "Obj %p Refs=%X, [Decremented]\n",
- object, new_count));
+ if (original_count) {
+ new_count = original_count - 1;
+ object->common.reference_count = new_count;
}
- if (object->common.type == ACPI_TYPE_METHOD) {
- ACPI_DEBUG_PRINT((ACPI_DB_ALLOCATIONS,
- "Method Obj %p Refs=%X, [Decremented]\n",
- object, new_count));
+ acpi_os_release_lock(acpi_gbl_reference_count_lock, lock_flags);
+
+ if (!original_count) {
+ ACPI_WARNING((AE_INFO,
+ "Obj %p, Reference Count is already zero, cannot decrement\n",
+ object));
}
- object->common.reference_count = new_count;
+ ACPI_DEBUG_PRINT((ACPI_DB_ALLOCATIONS,
+ "Obj %p Type %.2X Refs %.2X [Decremented]\n",
+ object, object->common.type, new_count));
+
+ /* Actually delete the object on a reference count of zero */
+
if (new_count == 0) {
acpi_ut_delete_internal_obj(object);
}
@@ -426,18 +439,20 @@ acpi_ut_update_ref_count(union acpi_operand_object *object, u32 action)
default:
- ACPI_ERROR((AE_INFO, "Unknown action (0x%X)", action));
- break;
+ acpi_os_release_lock(acpi_gbl_reference_count_lock, lock_flags);
+ ACPI_ERROR((AE_INFO, "Unknown Reference Count action (0x%X)",
+ action));
+ return;
}
/*
* Sanity check the reference count, for debug purposes only.
* (A deleted object will have a huge reference count)
*/
- if (count > ACPI_MAX_REFERENCE_COUNT) {
+ if (new_count > ACPI_MAX_REFERENCE_COUNT) {
ACPI_WARNING((AE_INFO,
- "Large Reference Count (0x%X) in object %p",
- count, object));
+ "Large Reference Count (0x%X) in object %p, Type=0x%.2X",
+ new_count, object, object->common.type));
}
}
@@ -702,7 +717,6 @@ void acpi_ut_remove_reference(union acpi_operand_object *object)
/*
* Allow a NULL pointer to be passed in, just ignore it. This saves
* each caller from having to check. Also, ignore NS nodes.
- *
*/
if (!object ||
(ACPI_GET_DESCRIPTOR_TYPE(object) == ACPI_DESC_TYPE_NAMED)) {
diff --git a/drivers/acpi/acpica/utmutex.c b/drivers/acpi/acpica/utmutex.c
index 22feb99..08c3232 100644
--- a/drivers/acpi/acpica/utmutex.c
+++ b/drivers/acpi/acpica/utmutex.c
@@ -81,7 +81,7 @@ acpi_status acpi_ut_mutex_initialize(void)
}
}
- /* Create the spinlocks for use at interrupt level */
+ /* Create the spinlocks for use at interrupt level or for speed */
status = acpi_os_create_lock (&acpi_gbl_gpe_lock);
if (ACPI_FAILURE (status)) {
@@ -93,7 +93,13 @@ acpi_status acpi_ut_mutex_initialize(void)
return_ACPI_STATUS (status);
}
+ status = acpi_os_create_lock(&acpi_gbl_reference_count_lock);
+ if (ACPI_FAILURE(status)) {
+ return_ACPI_STATUS(status);
+ }
+
/* Mutex for _OSI support */
+
status = acpi_os_create_mutex(&acpi_gbl_osi_mutex);
if (ACPI_FAILURE(status)) {
return_ACPI_STATUS(status);
@@ -136,6 +142,7 @@ void acpi_ut_mutex_terminate(void)
acpi_os_delete_lock(acpi_gbl_gpe_lock);
acpi_os_delete_lock(acpi_gbl_hardware_lock);
+ acpi_os_delete_lock(acpi_gbl_reference_count_lock);
/* Delete the reader/writer lock */
--
1.7.10
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