[PATCH V7 1/8] ACPI: I/O Remapping Table (IORT) initial support

On 21/06/16 08:12, Hanjun Guo wrote:

quoted

Hi Tomasz,

Sorry for jumping out late, just one comment below.

On 2016/6/20 19:02, Tomasz Nowicki wrote:

quoted

IORT shows representation of IO topology for ARM based systems.
It describes how various components are connected together on
parent-child basis e.g. PCI RC -> SMMU -> ITS. Also see IORT spec.

Initial support allows to detect IORT table presence and save its
root pointer obtained through acpi_get_table(). The pointer validity
depends on acpi_gbl_permanent_mmap because if acpi_gbl_permanent_mmap
is not set while using IORT nodes we would dereference unmapped pointers.

For the aforementioned reason call iort_table_detect() from acpi_init()
which guarantees acpi_gbl_permanent_mmap to be set at that point.

Add generic helpers which are helpful for scanning and retrieving
information from IORT table content. List of the most important helpers:
- iort_find_dev_node() finds IORT node for a given device
- iort_node_map_rid() maps device RID and returns IORT node which provides
   final translation

Signed-off-by: Tomasz Nowicki <redacted>
---
  drivers/acpi/Kconfig  |   3 +
  drivers/acpi/Makefile |   1 +
  drivers/acpi/bus.c    |   2 +
  drivers/acpi/iort.c   | 220 ++++++++++++++++++++++++++++++++++++++++++++++++++
  include/linux/iort.h  |  30 +++++++

[...]

quoted

+static acpi_status
+iort_match_node_callback(struct acpi_iort_node *node, void *context)
+{
+	struct device *dev = context;
+
+	switch (node->type) {
+	case ACPI_IORT_NODE_NAMED_COMPONENT: {
+		struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };

ACPI_ALLOCATE_BUFFER is used here, so ...

quoted

+		struct acpi_device *adev = to_acpi_device_node(dev->fwnode);
+		struct acpi_iort_named_component *ncomp;
+
+		if (!adev)
+			break;
+
+		ncomp = (struct acpi_iort_named_component *)node->node_data;
+
+		if (ACPI_FAILURE(acpi_get_name(adev->handle,
+					       ACPI_FULL_PATHNAME, &buffer))) {
+			dev_warn(dev, "Can't get device full path name\n");
+			break;
+		}
+
+		if (!strcmp(ncomp->device_name, (char *)buffer.pointer))
+			return AE_OK;

... we need to kfree(buffer.pointer) before we return or break.

For the record, I've queued this patch on top:

diff --git a/drivers/acpi/iort.c b/drivers/acpi/iort.c
index 496dcf6..3b9e55b 100644
--- a/drivers/acpi/iort.c
+++ b/drivers/acpi/iort.c

@@ -158,11 +158,15 @@ iort_match_node_callback(struct acpi_iort_node *node, void *context)
  		if (ACPI_FAILURE(acpi_get_name(adev->handle,
  					       ACPI_FULL_PATHNAME, &buffer))) {
  			dev_warn(dev, "Can't get device full path name\n");
-			break;
-		}
+		} else {
+			int match;

-		if (!strcmp(ncomp->device_name, (char *)buffer.pointer))
-			return AE_OK;
+			match = !strcmp(ncomp->device_name, buffer.pointer);
+			acpi_os_free(&buffer);
+
+			if (match)
+				return AE_OK;
+		}

  		break;
  	}

assuming that Rafael is OK with the general approach, of course.