Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 897 insertions, 0 deletions

diff --git a/drivers/acpi/acpica/dsmethod.c b/drivers/acpi/acpica/dsmethod.c
new file mode 100644
index 000000000..3b2ced5ab
--- /dev/null
+++ b/drivers/acpi/acpica/dsmethod.c
@@ -0,0 +1,897 @@
+// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
+/******************************************************************************
+ *
+ * Module Name: dsmethod - Parser/Interpreter interface - control method parsing
+ *
+ * Copyright (C) 2000 - 2026, Intel Corp.
+ *
+ *****************************************************************************/
+
+#include <acpi/acpi.h>
+#include "accommon.h"
+#include "acdispat.h"
+#include "acinterp.h"
+#include "acnamesp.h"
+#include "acparser.h"
+#include "amlcode.h"
+#include "acdebug.h"
+
+#define _COMPONENT          ACPI_DISPATCHER
+ACPI_MODULE_NAME("dsmethod")
+
+/* Local prototypes */
+static acpi_status
+acpi_ds_detect_named_opcodes(struct acpi_walk_state *walk_state,
+			     union acpi_parse_object **out_op);
+
+static acpi_status
+acpi_ds_create_method_mutex(union acpi_operand_object *method_desc);
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ds_auto_serialize_method
+ *
+ * PARAMETERS:  node                        - Namespace Node of the method
+ *              obj_desc                    - Method object attached to node
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Parse a control method AML to scan for control methods that
+ *              need serialization due to the creation of named objects.
+ *
+ * NOTE: It is a bit of overkill to mark all such methods serialized, since
+ * there is only a problem if the method actually blocks during execution.
+ * A blocking operation is, for example, a Sleep() operation, or any access
+ * to an operation region. However, it is probably not possible to easily
+ * detect whether a method will block or not, so we simply mark all suspicious
+ * methods as serialized.
+ *
+ * NOTE2: This code is essentially a generic routine for parsing a single
+ * control method.
+ *
+ ******************************************************************************/
+
+acpi_status
+acpi_ds_auto_serialize_method(struct acpi_namespace_node *node,
+			      union acpi_operand_object *obj_desc)
+{
+	acpi_status status;
+	union acpi_parse_object *op = NULL;
+	struct acpi_walk_state *walk_state;
+
+	ACPI_FUNCTION_TRACE_PTR(ds_auto_serialize_method, node);
+
+	ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
+			  "Method auto-serialization parse [%4.4s] %p\n",
+			  acpi_ut_get_node_name(node), node));
+
+	/* Create/Init a root op for the method parse tree */
+
+	op = acpi_ps_alloc_op(AML_METHOD_OP, obj_desc->method.aml_start);
+	if (!op) {
+		return_ACPI_STATUS(AE_NO_MEMORY);
+	}
+
+	acpi_ps_set_name(op, node->name.integer);
+	op->common.node = node;
+
+	/* Create and initialize a new walk state */
+
+	walk_state =
+	    acpi_ds_create_walk_state(node->owner_id, NULL, NULL, NULL);
+	if (!walk_state) {
+		acpi_ps_free_op(op);
+		return_ACPI_STATUS(AE_NO_MEMORY);
+	}
+
+	status = acpi_ds_init_aml_walk(walk_state, op, node,
+				       obj_desc->method.aml_start,
+				       obj_desc->method.aml_length, NULL, 0);
+	if (ACPI_FAILURE(status)) {
+		acpi_ds_delete_walk_state(walk_state);
+		acpi_ps_free_op(op);
+		return_ACPI_STATUS(status);
+	}
+
+	walk_state->descending_callback = acpi_ds_detect_named_opcodes;
+
+	/* Parse the method, scan for creation of named objects */
+
+	status = acpi_ps_parse_aml(walk_state);
+
+	acpi_ps_delete_parse_tree(op);
+	return_ACPI_STATUS(status);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ds_detect_named_opcodes
+ *
+ * PARAMETERS:  walk_state      - Current state of the parse tree walk
+ *              out_op          - Unused, required for parser interface
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Descending callback used during the loading of ACPI tables.
+ *              Currently used to detect methods that must be marked serialized
+ *              in order to avoid problems with the creation of named objects.
+ *
+ ******************************************************************************/
+
+static acpi_status
+acpi_ds_detect_named_opcodes(struct acpi_walk_state *walk_state,
+			     union acpi_parse_object **out_op)
+{
+
+	ACPI_FUNCTION_NAME(acpi_ds_detect_named_opcodes);
+
+	/* We are only interested in opcodes that create a new name */
+
+	if (!
+	    (walk_state->op_info->
+	     flags & (AML_NAMED | AML_CREATE | AML_FIELD))) {
+		return (AE_OK);
+	}
+
+	/*
+	 * At this point, we know we have a Named object opcode.
+	 * Mark the method as serialized. Later code will create a mutex for
+	 * this method to enforce serialization.
+	 *
+	 * Note, ACPI_METHOD_IGNORE_SYNC_LEVEL flag means that we will ignore the
+	 * Sync Level mechanism for this method, even though it is now serialized.
+	 * Otherwise, there can be conflicts with existing ASL code that actually
+	 * uses sync levels.
+	 */
+	walk_state->method_desc->method.sync_level = 0;
+	walk_state->method_desc->method.info_flags |=
+	    (ACPI_METHOD_SERIALIZED | ACPI_METHOD_IGNORE_SYNC_LEVEL);
+
+	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+			  "Method serialized [%4.4s] %p - [%s] (%4.4X)\n",
+			  walk_state->method_node->name.ascii,
+			  walk_state->method_node, walk_state->op_info->name,
+			  walk_state->opcode));
+
+	/* Abort the parse, no need to examine this method any further */
+
+	return (AE_CTRL_TERMINATE);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ds_method_error
+ *
+ * PARAMETERS:  status          - Execution status
+ *              walk_state      - Current state
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Called on method error. Invoke the global exception handler if
+ *              present, dump the method data if the debugger is configured
+ *
+ *              Note: Allows the exception handler to change the status code
+ *
+ ******************************************************************************/
+
+acpi_status
+acpi_ds_method_error(acpi_status status, struct acpi_walk_state *walk_state)
+{
+	u32 aml_offset;
+	acpi_name name = 0;
+
+	ACPI_FUNCTION_ENTRY();
+
+	/* Ignore AE_OK and control exception codes */
+
+	if (ACPI_SUCCESS(status) || (status & AE_CODE_CONTROL)) {
+		return (status);
+	}
+
+	/* Invoke the global exception handler */
+
+	if (acpi_gbl_exception_handler) {
+
+		/* Exit the interpreter, allow handler to execute methods */
+
+		acpi_ex_exit_interpreter();
+
+		/*
+		 * Handler can map the exception code to anything it wants, including
+		 * AE_OK, in which case the executing method will not be aborted.
+		 */
+		aml_offset = (u32)ACPI_PTR_DIFF(walk_state->aml,
+						walk_state->parser_state.
+						aml_start);
+
+		if (walk_state->method_node) {
+			name = walk_state->method_node->name.integer;
+		} else if (walk_state->deferred_node) {
+			name = walk_state->deferred_node->name.integer;
+		}
+
+		status = acpi_gbl_exception_handler(status, name,
+						    walk_state->opcode,
+						    aml_offset, NULL);
+		acpi_ex_enter_interpreter();
+	}
+
+	acpi_ds_clear_implicit_return(walk_state);
+
+	if (ACPI_FAILURE(status)) {
+		acpi_ds_dump_method_stack(status, walk_state, walk_state->op);
+
+		/* Display method locals/args if debugger is present */
+
+#ifdef ACPI_DEBUGGER
+		acpi_db_dump_method_info(status, walk_state);
+#endif
+	}
+
+	return (status);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ds_create_method_mutex
+ *
+ * PARAMETERS:  obj_desc            - The method object
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Create a mutex object for a serialized control method
+ *
+ ******************************************************************************/
+
+static acpi_status
+acpi_ds_create_method_mutex(union acpi_operand_object *method_desc)
+{
+	union acpi_operand_object *mutex_desc;
+	acpi_status status;
+
+	ACPI_FUNCTION_TRACE(ds_create_method_mutex);
+
+	/* Create the new mutex object */
+
+	mutex_desc = acpi_ut_create_internal_object(ACPI_TYPE_MUTEX);
+	if (!mutex_desc) {
+		return_ACPI_STATUS(AE_NO_MEMORY);
+	}
+
+	/* Create the actual OS Mutex */
+
+	status = acpi_os_create_mutex(&mutex_desc->mutex.os_mutex);
+	if (ACPI_FAILURE(status)) {
+		acpi_ut_delete_object_desc(mutex_desc);
+		return_ACPI_STATUS(status);
+	}
+
+	mutex_desc->mutex.sync_level = method_desc->method.sync_level;
+	method_desc->method.mutex = mutex_desc;
+	return_ACPI_STATUS(AE_OK);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ds_begin_method_execution
+ *
+ * PARAMETERS:  method_node         - Node of the method
+ *              obj_desc            - The method object
+ *              walk_state          - current state, NULL if not yet executing
+ *                                    a method.
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Prepare a method for execution. Parses the method if necessary,
+ *              increments the thread count, and waits at the method semaphore
+ *              for clearance to execute.
+ *
+ ******************************************************************************/
+
+acpi_status
+acpi_ds_begin_method_execution(struct acpi_namespace_node *method_node,
+			       union acpi_operand_object *obj_desc,
+			       struct acpi_walk_state *walk_state)
+{
+	acpi_status status = AE_OK;
+
+	ACPI_FUNCTION_TRACE_PTR(ds_begin_method_execution, method_node);
+
+	if (!method_node) {
+		return_ACPI_STATUS(AE_NULL_ENTRY);
+	}
+
+	acpi_ex_start_trace_method(method_node, obj_desc, walk_state);
+
+	/* Prevent wraparound of thread count */
+
+	if (obj_desc->method.thread_count == ACPI_UINT8_MAX) {
+		ACPI_ERROR((AE_INFO,
+			    "Method reached maximum reentrancy limit (255)"));
+		return_ACPI_STATUS(AE_AML_METHOD_LIMIT);
+	}
+
+	/*
+	 * If this method is serialized, we need to acquire the method mutex.
+	 */
+	if (obj_desc->method.info_flags & ACPI_METHOD_SERIALIZED) {
+		/*
+		 * Create a mutex for the method if it is defined to be Serialized
+		 * and a mutex has not already been created. We defer the mutex creation
+		 * until a method is actually executed, to minimize the object count
+		 */
+		if (!obj_desc->method.mutex) {
+			status = acpi_ds_create_method_mutex(obj_desc);
+			if (ACPI_FAILURE(status)) {
+				return_ACPI_STATUS(status);
+			}
+		}
+
+		/*
+		 * The current_sync_level (per-thread) must be less than or equal to
+		 * the sync level of the method. This mechanism provides some
+		 * deadlock prevention.
+		 *
+		 * If the method was auto-serialized, we just ignore the sync level
+		 * mechanism, because auto-serialization of methods can interfere
+		 * with ASL code that actually uses sync levels.
+		 *
+		 * Top-level method invocation has no walk state at this point
+		 */
+		if (walk_state &&
+		    (!(obj_desc->method.
+		       info_flags & ACPI_METHOD_IGNORE_SYNC_LEVEL))
+		    && (walk_state->thread->current_sync_level >
+			obj_desc->method.mutex->mutex.sync_level)) {
+			ACPI_ERROR((AE_INFO,
+				    "Cannot acquire Mutex for method [%4.4s]"
+				    ", current SyncLevel is too large (%u)",
+				    acpi_ut_get_node_name(method_node),
+				    walk_state->thread->current_sync_level));
+
+			return_ACPI_STATUS(AE_AML_MUTEX_ORDER);
+		}
+
+		/*
+		 * Obtain the method mutex if necessary. Do not acquire mutex for a
+		 * recursive call.
+		 */
+		if (!walk_state ||
+		    !obj_desc->method.mutex->mutex.thread_id ||
+		    (walk_state->thread->thread_id !=
+		     obj_desc->method.mutex->mutex.thread_id)) {
+			/*
+			 * Acquire the method mutex. This releases the interpreter if we
+			 * block (and reacquires it before it returns)
+			 */
+			status =
+			    acpi_ex_system_wait_mutex(obj_desc->method.mutex->
+						      mutex.os_mutex,
+						      ACPI_WAIT_FOREVER);
+			if (ACPI_FAILURE(status)) {
+				return_ACPI_STATUS(status);
+			}
+
+			/* Update the mutex and walk info and save the original sync_level */
+
+			if (walk_state) {
+				obj_desc->method.mutex->mutex.
+				    original_sync_level =
+				    walk_state->thread->current_sync_level;
+
+				obj_desc->method.mutex->mutex.thread_id =
+				    walk_state->thread->thread_id;
+
+				/*
+				 * Update the current sync_level only if this is not an auto-
+				 * serialized method. In the auto case, we have to ignore
+				 * the sync level for the method mutex (created for the
+				 * auto-serialization) because we have no idea of what the
+				 * sync level should be. Therefore, just ignore it.
+				 */
+				if (!(obj_desc->method.info_flags &
+				      ACPI_METHOD_IGNORE_SYNC_LEVEL)) {
+					walk_state->thread->current_sync_level =
+					    obj_desc->method.sync_level;
+				}
+			} else {
+				obj_desc->method.mutex->mutex.
+				    original_sync_level =
+				    obj_desc->method.mutex->mutex.sync_level;
+
+				obj_desc->method.mutex->mutex.thread_id =
+				    acpi_os_get_thread_id();
+			}
+		}
+
+		/* Always increase acquisition depth */
+
+		obj_desc->method.mutex->mutex.acquisition_depth++;
+	}
+
+	/*
+	 * Allocate an Owner ID for this method, only if this is the first thread
+	 * to begin concurrent execution. We only need one owner_id, even if the
+	 * method is invoked recursively.
+	 */
+	if (!obj_desc->method.owner_id) {
+		status = acpi_ut_allocate_owner_id(&obj_desc->method.owner_id);
+		if (ACPI_FAILURE(status)) {
+			goto cleanup;
+		}
+	}
+
+	/*
+	 * Increment the method parse tree thread count since it has been
+	 * reentered one more time (even if it is the same thread)
+	 */
+	obj_desc->method.thread_count++;
+	acpi_method_count++;
+	return_ACPI_STATUS(status);
+
+cleanup:
+	/* On error, must release the method mutex (if present) */
+
+	if (obj_desc->method.mutex) {
+		acpi_os_release_mutex(obj_desc->method.mutex->mutex.os_mutex);
+	}
+	return_ACPI_STATUS(status);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ds_call_control_method
+ *
+ * PARAMETERS:  thread              - Info for this thread
+ *              this_walk_state     - Current walk state
+ *              op                  - Current Op to be walked
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Transfer execution to a called control method
+ *
+ ******************************************************************************/
+
+acpi_status
+acpi_ds_call_control_method(struct acpi_thread_state *thread,
+			    struct acpi_walk_state *this_walk_state,
+			    union acpi_parse_object *op)
+{
+	acpi_status status;
+	struct acpi_namespace_node *method_node;
+	struct acpi_walk_state *next_walk_state = NULL;
+	union acpi_operand_object *obj_desc;
+	struct acpi_evaluate_info *info;
+
+	ACPI_FUNCTION_TRACE_PTR(ds_call_control_method, this_walk_state);
+
+	ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
+			  "Calling method %p, currentstate=%p\n",
+			  this_walk_state->prev_op, this_walk_state));
+
+	/*
+	 * Get the namespace entry for the control method we are about to call
+	 */
+	method_node = this_walk_state->method_call_node;
+	if (!method_node) {
+		return_ACPI_STATUS(AE_NULL_ENTRY);
+	}
+
+	obj_desc = acpi_ns_get_attached_object(method_node);
+	if (!obj_desc) {
+		return_ACPI_STATUS(AE_NULL_OBJECT);
+	}
+
+	if (this_walk_state->num_operands < obj_desc->method.param_count) {
+		ACPI_ERROR((AE_INFO, "Missing argument(s) for method [%4.4s]",
+			    acpi_ut_get_node_name(method_node)));
+
+		return_ACPI_STATUS(AE_AML_TOO_FEW_ARGUMENTS);
+	}
+
+	else if (this_walk_state->num_operands > obj_desc->method.param_count) {
+		ACPI_ERROR((AE_INFO, "Too many arguments for method [%4.4s]",
+			    acpi_ut_get_node_name(method_node)));
+
+		return_ACPI_STATUS(AE_AML_TOO_MANY_ARGUMENTS);
+	}
+
+	/* Init for new method, possibly wait on method mutex */
+
+	status =
+	    acpi_ds_begin_method_execution(method_node, obj_desc,
+					   this_walk_state);
+	if (ACPI_FAILURE(status)) {
+		return_ACPI_STATUS(status);
+	}
+
+	/* Begin method parse/execution. Create a new walk state */
+
+	next_walk_state =
+	    acpi_ds_create_walk_state(obj_desc->method.owner_id, NULL, obj_desc,
+				      thread);
+	if (!next_walk_state) {
+		status = AE_NO_MEMORY;
+		goto cleanup;
+	}
+
+	/*
+	 * The resolved arguments were put on the previous walk state's operand
+	 * stack. Operands on the previous walk state stack always
+	 * start at index 0. Also, null terminate the list of arguments
+	 */
+	this_walk_state->operands[this_walk_state->num_operands] = NULL;
+
+	/*
+	 * Allocate and initialize the evaluation information block
+	 * TBD: this is somewhat inefficient, should change interface to
+	 * ds_init_aml_walk. For now, keeps this struct off the CPU stack
+	 */
+	info = ACPI_ALLOCATE_ZEROED(sizeof(struct acpi_evaluate_info));
+	if (!info) {
+		status = AE_NO_MEMORY;
+		goto pop_walk_state;
+	}
+
+	info->parameters = &this_walk_state->operands[0];
+
+	status = acpi_ds_init_aml_walk(next_walk_state, NULL, method_node,
+				       obj_desc->method.aml_start,
+				       obj_desc->method.aml_length, info,
+				       ACPI_IMODE_EXECUTE);
+
+	ACPI_FREE(info);
+	if (ACPI_FAILURE(status)) {
+		goto pop_walk_state;
+	}
+
+	next_walk_state->method_nesting_depth =
+	    this_walk_state->method_nesting_depth + 1;
+
+	/*
+	 * Delete the operands on the previous walkstate operand stack
+	 * (they were copied to new objects)
+	 */
+	acpi_ds_clear_operands(this_walk_state);
+
+	ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
+			  "**** Begin nested execution of [%4.4s] **** WalkState=%p\n",
+			  method_node->name.ascii, next_walk_state));
+
+	this_walk_state->method_pathname =
+	    acpi_ns_get_normalized_pathname(method_node, TRUE);
+	this_walk_state->method_is_nested = TRUE;
+
+	/* Optional object evaluation log */
+
+	ACPI_DEBUG_PRINT_RAW((ACPI_DB_EVALUATION,
+			      "%-26s:  %*s%s\n", "   Nested method call",
+			      next_walk_state->method_nesting_depth * 3, " ",
+			      &this_walk_state->method_pathname[1]));
+
+	/* Invoke an internal method if necessary */
+
+	if (obj_desc->method.info_flags & ACPI_METHOD_INTERNAL_ONLY) {
+		status =
+		    obj_desc->method.dispatch.implementation(next_walk_state);
+		if (status == AE_OK) {
+			status = AE_CTRL_TERMINATE;
+		}
+	}
+
+	return_ACPI_STATUS(status);
+
+pop_walk_state:
+
+	/* On error, pop the walk state to be deleted from thread */
+
+	acpi_ds_pop_walk_state(thread);
+
+cleanup:
+
+	/* On error, we must terminate the method properly */
+
+	acpi_ds_terminate_control_method(obj_desc, next_walk_state);
+	acpi_ds_delete_walk_state(next_walk_state);
+
+	return_ACPI_STATUS(status);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ds_restart_control_method
+ *
+ * PARAMETERS:  walk_state          - State for preempted method (caller)
+ *              return_desc         - Return value from the called method
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Restart a method that was preempted by another (nested) method
+ *              invocation. Handle the return value (if any) from the callee.
+ *
+ ******************************************************************************/
+
+acpi_status
+acpi_ds_restart_control_method(struct acpi_walk_state *walk_state,
+			       union acpi_operand_object *return_desc)
+{
+	acpi_status status;
+	int same_as_implicit_return;
+
+	ACPI_FUNCTION_TRACE_PTR(ds_restart_control_method, walk_state);
+
+	ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
+			  "****Restart [%4.4s] Op %p ReturnValueFromCallee %p\n",
+			  acpi_ut_get_node_name(walk_state->method_node),
+			  walk_state->method_call_op, return_desc));
+
+	ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
+			  "    ReturnFromThisMethodUsed?=%X ResStack %p Walk %p\n",
+			  walk_state->return_used,
+			  walk_state->results, walk_state));
+
+	/* Did the called method return a value? */
+
+	if (return_desc) {
+
+		/* Is the implicit return object the same as the return desc? */
+
+		same_as_implicit_return =
+		    (walk_state->implicit_return_obj == return_desc);
+
+		/* Are we actually going to use the return value? */
+
+		if (walk_state->return_used) {
+
+			/* Save the return value from the previous method */
+
+			status = acpi_ds_result_push(return_desc, walk_state);
+			if (ACPI_FAILURE(status)) {
+				acpi_ut_remove_reference(return_desc);
+				return_ACPI_STATUS(status);
+			}
+
+			/*
+			 * Save as THIS method's return value in case it is returned
+			 * immediately to yet another method
+			 */
+			walk_state->return_desc = return_desc;
+		}
+
+		/*
+		 * The following code is the optional support for the so-called
+		 * "implicit return". Some AML code assumes that the last value of the
+		 * method is "implicitly" returned to the caller, in the absence of an
+		 * explicit return value.
+		 *
+		 * Just save the last result of the method as the return value.
+		 *
+		 * NOTE: this is optional because the ASL language does not actually
+		 * support this behavior.
+		 */
+		else if (!acpi_ds_do_implicit_return
+			 (return_desc, walk_state, FALSE)
+			 || same_as_implicit_return) {
+			/*
+			 * Delete the return value if it will not be used by the
+			 * calling method or remove one reference if the explicit return
+			 * is the same as the implicit return value.
+			 */
+			acpi_ut_remove_reference(return_desc);
+		}
+	}
+
+	return_ACPI_STATUS(AE_OK);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ds_terminate_control_method
+ *
+ * PARAMETERS:  method_desc         - Method object
+ *              walk_state          - State associated with the method
+ *
+ * RETURN:      None
+ *
+ * DESCRIPTION: Terminate a control method. Delete everything that the method
+ *              created, delete all locals and arguments, and delete the parse
+ *              tree if requested.
+ *
+ * MUTEX:       Interpreter is locked
+ *
+ ******************************************************************************/
+
+void
+acpi_ds_terminate_control_method(union acpi_operand_object *method_desc,
+				 struct acpi_walk_state *walk_state)
+{
+	u32 i;
+	struct acpi_namespace_node *ref_node;
+
+	ACPI_FUNCTION_TRACE_PTR(ds_terminate_control_method, walk_state);
+
+	/* method_desc is required, walk_state is optional */
+
+	if (!method_desc) {
+		return_VOID;
+	}
+
+	if (walk_state) {
+		/*
+		 * Check if the return value is a ref_of reference to a method local
+		 * or argument. If so, clear the reference to avoid use-after-free
+		 * when the walk state is deleted.
+		 */
+		if (walk_state->return_desc &&
+		    (walk_state->return_desc->common.type ==
+		     ACPI_TYPE_LOCAL_REFERENCE)
+		    && (walk_state->return_desc->reference.class ==
+			ACPI_REFCLASS_REFOF)) {
+			ref_node = walk_state->return_desc->reference.object;
+			if (ref_node) {
+
+				/* Check against method locals */
+				for (i = 0; i < ACPI_METHOD_NUM_LOCALS; i++) {
+					if (ref_node ==
+					    &walk_state->local_variables[i]) {
+						acpi_ut_remove_reference
+						    (walk_state->return_desc);
+						walk_state->return_desc = NULL;
+						break;
+					}
+				}
+
+				/* Check against method arguments if not already cleared */
+				if (walk_state->return_desc) {
+					for (i = 0; i < ACPI_METHOD_NUM_ARGS;
+					     i++) {
+						if (ref_node ==
+						    &walk_state->arguments[i]) {
+							acpi_ut_remove_reference
+							    (walk_state->
+							     return_desc);
+							walk_state->
+							    return_desc = NULL;
+							break;
+						}
+					}
+				}
+			}
+		}
+
+		/* Delete all arguments and locals */
+
+		acpi_ds_method_data_delete_all(walk_state);
+
+		/*
+		 * Delete any namespace objects created anywhere within the
+		 * namespace by the execution of this method. Unless:
+		 * 1) This method is a module-level executable code method, in which
+		 *    case we want make the objects permanent.
+		 * 2) There are other threads executing the method, in which case we
+		 *    will wait until the last thread has completed.
+		 */
+		if (!(method_desc->method.info_flags & ACPI_METHOD_MODULE_LEVEL)
+		    && (method_desc->method.thread_count == 1)) {
+
+			/* Delete any direct children of (created by) this method */
+
+			(void)acpi_ex_exit_interpreter();
+			acpi_ns_delete_namespace_subtree(walk_state->
+							 method_node);
+			(void)acpi_ex_enter_interpreter();
+
+			/*
+			 * Delete any objects that were created by this method
+			 * elsewhere in the namespace (if any were created).
+			 * Use of the ACPI_METHOD_MODIFIED_NAMESPACE optimizes the
+			 * deletion such that we don't have to perform an entire
+			 * namespace walk for every control method execution.
+			 */
+			if (method_desc->method.
+			    info_flags & ACPI_METHOD_MODIFIED_NAMESPACE) {
+				(void)acpi_ex_exit_interpreter();
+				acpi_ns_delete_namespace_by_owner(method_desc->
+								  method.
+								  owner_id);
+				(void)acpi_ex_enter_interpreter();
+				method_desc->method.info_flags &=
+				    ~ACPI_METHOD_MODIFIED_NAMESPACE;
+			}
+		}
+
+		/*
+		 * If method is serialized, release the mutex and restore the
+		 * current sync level for this thread
+		 */
+		if (method_desc->method.mutex) {
+
+			/* Acquisition Depth handles recursive calls */
+
+			method_desc->method.mutex->mutex.acquisition_depth--;
+			if (!method_desc->method.mutex->mutex.acquisition_depth) {
+				walk_state->thread->current_sync_level =
+				    method_desc->method.mutex->mutex.
+				    original_sync_level;
+
+				acpi_os_release_mutex(method_desc->method.
+						      mutex->mutex.os_mutex);
+				method_desc->method.mutex->mutex.thread_id = 0;
+			}
+		}
+	}
+
+	/* Decrement the thread count on the method */
+
+	if (method_desc->method.thread_count) {
+		method_desc->method.thread_count--;
+	} else {
+		ACPI_ERROR((AE_INFO, "Invalid zero thread count in method"));
+	}
+
+	/* Are there any other threads currently executing this method? */
+
+	if (method_desc->method.thread_count) {
+		/*
+		 * Additional threads. Do not release the owner_id in this case,
+		 * we immediately reuse it for the next thread executing this method
+		 */
+		ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
+				  "*** Completed execution of one thread, %u threads remaining\n",
+				  method_desc->method.thread_count));
+	} else {
+		/* This is the only executing thread for this method */
+
+		/*
+		 * Support to dynamically change a method from not_serialized to
+		 * Serialized if it appears that the method is incorrectly written and
+		 * does not support multiple thread execution. The best example of this
+		 * is if such a method creates namespace objects and blocks. A second
+		 * thread will fail with an AE_ALREADY_EXISTS exception.
+		 *
+		 * This code is here because we must wait until the last thread exits
+		 * before marking the method as serialized.
+		 */
+		if (method_desc->method.
+		    info_flags & ACPI_METHOD_SERIALIZED_PENDING) {
+			if (walk_state) {
+				ACPI_INFO(("Marking method %4.4s as Serialized "
+					   "because of AE_ALREADY_EXISTS error",
+					   walk_state->method_node->name.
+					   ascii));
+			}
+
+			/*
+			 * Method tried to create an object twice and was marked as
+			 * "pending serialized". The probable cause is that the method
+			 * cannot handle reentrancy.
+			 *
+			 * The method was created as not_serialized, but it tried to create
+			 * a named object and then blocked, causing the second thread
+			 * entrance to begin and then fail. Workaround this problem by
+			 * marking the method permanently as Serialized when the last
+			 * thread exits here.
+			 */
+			method_desc->method.info_flags &=
+			    ~ACPI_METHOD_SERIALIZED_PENDING;
+
+			method_desc->method.info_flags |=
+			    (ACPI_METHOD_SERIALIZED |
+			     ACPI_METHOD_IGNORE_SYNC_LEVEL);
+			method_desc->method.sync_level = 0;
+		}
+
+		/* No more threads, we can free the owner_id */
+
+		if (!
+		    (method_desc->method.
+		     info_flags & ACPI_METHOD_MODULE_LEVEL)) {
+			acpi_ut_release_owner_id(&method_desc->method.owner_id);
+		}
+	}
+
+	acpi_ex_stop_trace_method((struct acpi_namespace_node *)method_desc->
+				  method.node, method_desc, walk_state);
+
+	return_VOID;
+}