Merge tag 'acpi-5.12-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull more ACPI updates from Rafael Wysocki:
 "Fix race condition in generic_serial_bus (I2C) and GPIO Operation
  Region handling in ACPICA and reduce some related code duplication
  (Hans de Goede)"

* tag 'acpi-5.12-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPICA: Remove some code duplication from acpi_ev_address_space_dispatch
  ACPICA: Fix race in generic_serial_bus (I2C) and GPIO op_region parameter handling

4 files changed, 53 insertions, 26 deletions

diff --git a/drivers/acpi/acpica/acobject.h b/drivers/acpi/acpica/acobject.h
index af47a3ffd2a4..9db5ae0f79ea 100644
--- a/drivers/acpi/acpica/acobject.h
+++ b/drivers/acpi/acpica/acobject.h
@@ -284,6 +284,7 @@ struct acpi_object_addr_handler {
 	acpi_adr_space_handler handler;
 	struct acpi_namespace_node *node;	/* Parent device */
 	void *context;
+	acpi_mutex context_mutex;
 	acpi_adr_space_setup setup;
 	union acpi_operand_object *region_list;	/* Regions using this handler */
 	union acpi_operand_object *next;
diff --git a/drivers/acpi/acpica/evhandler.c b/drivers/acpi/acpica/evhandler.c
index ea9485e6a475..c0cd7147a5a3 100644
--- a/drivers/acpi/acpica/evhandler.c
+++ b/drivers/acpi/acpica/evhandler.c
@@ -489,6 +489,13 @@ acpi_ev_install_space_handler(struct acpi_namespace_node *node,
 
 	/* Init handler obj */
 
+	status =
+	    acpi_os_create_mutex(&handler_obj->address_space.context_mutex);
+	if (ACPI_FAILURE(status)) {
+		acpi_ut_remove_reference(handler_obj);
+		goto unlock_and_exit;
+	}
+
 	handler_obj->address_space.space_id = (u8)space_id;
 	handler_obj->address_space.handler_flags = flags;
 	handler_obj->address_space.region_list = NULL;
diff --git a/drivers/acpi/acpica/evregion.c b/drivers/acpi/acpica/evregion.c
index 3ed7d9ae95cf..4ef43c8ef5e7 100644
--- a/drivers/acpi/acpica/evregion.c
+++ b/drivers/acpi/acpica/evregion.c
@@ -112,6 +112,8 @@ acpi_ev_address_space_dispatch(union acpi_operand_object *region_obj,
 	union acpi_operand_object *region_obj2;
 	void *region_context = NULL;
 	struct acpi_connection_info *context;
+	acpi_mutex context_mutex;
+	u8 context_locked;
 	acpi_physical_address address;
 
 	ACPI_FUNCTION_TRACE(ev_address_space_dispatch);
@@ -136,6 +138,8 @@ acpi_ev_address_space_dispatch(union acpi_operand_object *region_obj,
 	}
 
 	context = handler_desc->address_space.context;
+	context_mutex = handler_desc->address_space.context_mutex;
+	context_locked = FALSE;
 
 	/*
 	 * It may be the case that the region has never been initialized.
@@ -204,6 +208,23 @@ acpi_ev_address_space_dispatch(union acpi_operand_object *region_obj,
 	handler = handler_desc->address_space.handler;
 	address = (region_obj->region.address + region_offset);
 
+	ACPI_DEBUG_PRINT((ACPI_DB_OPREGION,
+			  "Handler %p (@%p) Address %8.8X%8.8X [%s]\n",
+			  &region_obj->region.handler->address_space, handler,
+			  ACPI_FORMAT_UINT64(address),
+			  acpi_ut_get_region_name(region_obj->region.
+						  space_id)));
+
+	if (!(handler_desc->address_space.handler_flags &
+	      ACPI_ADDR_HANDLER_DEFAULT_INSTALLED)) {
+		/*
+		 * For handlers other than the default (supplied) handlers, we must
+		 * exit the interpreter because the handler *might* block -- we don't
+		 * know what it will do, so we can't hold the lock on the interpreter.
+		 */
+		acpi_ex_exit_interpreter();
+	}
+
 	/*
 	 * Special handling for generic_serial_bus and general_purpose_io:
 	 * There are three extra parameters that must be passed to the
@@ -212,48 +233,39 @@ acpi_ev_address_space_dispatch(union acpi_operand_object *region_obj,
 	 *   2) Length of the above buffer
 	 *   3) Actual access length from the access_as() op
 	 *
+	 * Since we pass these extra parameters via the context, which is
+	 * shared between threads, we must lock the context to avoid these
+	 * parameters being changed from another thread before the handler
+	 * has completed running.
+	 *
 	 * In addition, for general_purpose_io, the Address and bit_width fields
 	 * are defined as follows:
 	 *   1) Address is the pin number index of the field (bit offset from
 	 *      the previous Connection)
 	 *   2) bit_width is the actual bit length of the field (number of pins)
 	 */
-	if ((region_obj->region.space_id == ACPI_ADR_SPACE_GSBUS) &&
+	if ((region_obj->region.space_id == ACPI_ADR_SPACE_GSBUS ||
+	     region_obj->region.space_id == ACPI_ADR_SPACE_GPIO) &&
 	    context && field_obj) {
 
-		/* Get the Connection (resource_template) buffer */
+		status =
+		    acpi_os_acquire_mutex(context_mutex, ACPI_WAIT_FOREVER);
+		if (ACPI_FAILURE(status)) {
+			goto re_enter_interpreter;
+		}
 
-		context->connection = field_obj->field.resource_buffer;
-		context->length = field_obj->field.resource_length;
-		context->access_length = field_obj->field.access_length;
-	}
-	if ((region_obj->region.space_id == ACPI_ADR_SPACE_GPIO) &&
-	    context && field_obj) {
+		context_locked = TRUE;
 
 		/* Get the Connection (resource_template) buffer */
 
 		context->connection = field_obj->field.resource_buffer;
 		context->length = field_obj->field.resource_length;
 		context->access_length = field_obj->field.access_length;
-		address = field_obj->field.pin_number_index;
-		bit_width = field_obj->field.bit_length;
-	}
-
-	ACPI_DEBUG_PRINT((ACPI_DB_OPREGION,
-			  "Handler %p (@%p) Address %8.8X%8.8X [%s]\n",
-			  &region_obj->region.handler->address_space, handler,
-			  ACPI_FORMAT_UINT64(address),
-			  acpi_ut_get_region_name(region_obj->region.
-						  space_id)));
 
-	if (!(handler_desc->address_space.handler_flags &
-	      ACPI_ADDR_HANDLER_DEFAULT_INSTALLED)) {
-		/*
-		 * For handlers other than the default (supplied) handlers, we must
-		 * exit the interpreter because the handler *might* block -- we don't
-		 * know what it will do, so we can't hold the lock on the interpreter.
-		 */
-		acpi_ex_exit_interpreter();
+		if (region_obj->region.space_id == ACPI_ADR_SPACE_GPIO) {
+			address = field_obj->field.pin_number_index;
+			bit_width = field_obj->field.bit_length;
+		}
 	}
 
 	/* Call the handler */
@@ -261,6 +273,10 @@ acpi_ev_address_space_dispatch(union acpi_operand_object *region_obj,
 	status = handler(function, address, bit_width, value, context,
 			 region_obj2->extra.region_context);
 
+	if (context_locked) {
+		acpi_os_release_mutex(context_mutex);
+	}
+
 	if (ACPI_FAILURE(status)) {
 		ACPI_EXCEPTION((AE_INFO, status, "Returned by Handler for [%s]",
 				acpi_ut_get_region_name(region_obj->region.
@@ -277,6 +293,7 @@ acpi_ev_address_space_dispatch(union acpi_operand_object *region_obj,
 		}
 	}
 
+re_enter_interpreter:
 	if (!(handler_desc->address_space.handler_flags &
 	      ACPI_ADDR_HANDLER_DEFAULT_INSTALLED)) {
 		/*
diff --git a/drivers/acpi/acpica/evxfregn.c b/drivers/acpi/acpica/evxfregn.c
index 7672d70da850..b1ff0a8f9c14 100644
--- a/drivers/acpi/acpica/evxfregn.c
+++ b/drivers/acpi/acpica/evxfregn.c
@@ -201,6 +201,8 @@ acpi_remove_address_space_handler(acpi_handle device,
 
 			/* Now we can delete the handler object */
 
+			acpi_os_release_mutex(handler_obj->address_space.
+					      context_mutex);
 			acpi_ut_remove_reference(handler_obj);
 			goto unlock_and_exit;
 		}