2022-06-09 14:22:49

by Rafael J. Wysocki

Subject: [PATCH v1 09/16] ACPI: video: Use acpi_dev_for_each_child()

From: Rafael J. Wysocki <[email protected]>

Instead of walking the list of children of an ACPI device directly,
use acpi_dev_for_each_child() to carry out an action for all of
the given ACPI device's children.

This will help to eliminate the children list head from struct
acpi_device as it is redundant and it is used in questionable ways
in some places (in particular, locking is needed for walking the
list pointed to it safely, but it is often missing).

Signed-off-by: Rafael J. Wysocki <[email protected]>
---
drivers/acpi/acpi_video.c | 42 +++++++++++++++++-------------------------
1 file changed, 17 insertions(+), 25 deletions(-)

Index: linux-pm/drivers/acpi/acpi_video.c
===================================================================
--- linux-pm.orig/drivers/acpi/acpi_video.c
+++ linux-pm/drivers/acpi/acpi_video.c
@@ -1149,24 +1149,25 @@ acpi_video_get_device_type(struct acpi_v
return 0;
}

-static int
-acpi_video_bus_get_one_device(struct acpi_device *device,
- struct acpi_video_bus *video)
+static int acpi_video_bus_get_one_device(struct acpi_device *device, void *arg)
{
- unsigned long long device_id;
- int status, device_type;
- struct acpi_video_device *data;
+ struct acpi_video_bus *video = arg;
struct acpi_video_device_attrib *attribute;
+ struct acpi_video_device *data;
+ unsigned long long device_id;
+ acpi_status status;
+ int device_type;

- status =
- acpi_evaluate_integer(device->handle, "_ADR", NULL, &device_id);
- /* Some device omits _ADR, we skip them instead of fail */
+ status = acpi_evaluate_integer(device->handle, "_ADR", NULL, &device_id);
+ /* Skip devices without _ADR instead of failing. */
if (ACPI_FAILURE(status))
- return 0;
+ goto exit;

data = kzalloc(sizeof(struct acpi_video_device), GFP_KERNEL);
- if (!data)
+ if (!data) {
+ dev_dbg(&device->dev, "Cannot attach\n");
return -ENOMEM;
+ }

strcpy(acpi_device_name(device), ACPI_VIDEO_DEVICE_NAME);
strcpy(acpi_device_class(device), ACPI_VIDEO_CLASS);
@@ -1226,7 +1227,9 @@ acpi_video_bus_get_one_device(struct acp
list_add_tail(&data->entry, &video->video_device_list);
mutex_unlock(&video->device_list_lock);

- return status;
+exit:
+ video->child_count++;
+ return 0;
}

/*
@@ -1538,9 +1541,6 @@ static int
acpi_video_bus_get_devices(struct acpi_video_bus *video,
struct acpi_device *device)
{
- int status = 0;
- struct acpi_device *dev;
-
/*
* There are systems where video module known to work fine regardless
* of broken _DOD and ignoring returned value here doesn't cause
@@ -1548,16 +1548,8 @@ acpi_video_bus_get_devices(struct acpi_v
*/
acpi_video_device_enumerate(video);

- list_for_each_entry(dev, &device->children, node) {
-
- status = acpi_video_bus_get_one_device(dev, video);
- if (status) {
- dev_err(&dev->dev, "Can't attach device\n");
- break;
- }
- video->child_count++;
- }
- return status;
+ return acpi_dev_for_each_child(device, acpi_video_bus_get_one_device,
+ video);
}

/* acpi_video interface */

2022-06-09 15:49:29

by Andy Shevchenko

Subject: Re: [PATCH v1 09/16] ACPI: video: Use acpi_dev_for_each_child()

On Thu, Jun 09, 2022 at 04:03:37PM +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <[email protected]>
>
> Instead of walking the list of children of an ACPI device directly,
> use acpi_dev_for_each_child() to carry out an action for all of
> the given ACPI device's children.

...

> + return acpi_dev_for_each_child(device, acpi_video_bus_get_one_device,
> + video);

Perhaps one line?

--
With Best Regards,
Andy Shevchenko