Add `__free` function attribute to `np` device_node pointer
initialisation and remove of_node_put cleanup for this pointer.
The `__free` attribute is used for scope based cleanup instead of
manually freeing the resource using `of_node_put`, making cleanup
simpler and safer.
Suggested-by: Julia Lawall <[email protected]>
Signed-off-by: Shresth Prasad <[email protected]>
---
drivers/video/backlight/sky81452-backlight.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
diff --git a/drivers/video/backlight/sky81452-backlight.c b/drivers/video/backlight/sky81452-backlight.c
index eb18c6eb0ff0..3c5d8125080c 100644
--- a/drivers/video/backlight/sky81452-backlight.c
+++ b/drivers/video/backlight/sky81452-backlight.c
@@ -182,7 +182,7 @@ static const struct attribute_group sky81452_bl_attr_group = {
static struct sky81452_bl_platform_data *sky81452_bl_parse_dt(
struct device *dev)
{
- struct device_node *np = of_node_get(dev->of_node);
+ struct device_node *np __free(device_node) = of_node_get(dev->of_node);
struct sky81452_bl_platform_data *pdata;
int num_entry;
unsigned int sources[6];
@@ -194,10 +194,8 @@ static struct sky81452_bl_platform_data *sky81452_bl_parse_dt(
}
pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
- if (!pdata) {
- of_node_put(np);
+ if (!pdata)
return ERR_PTR(-ENOMEM);
- }
of_property_read_string(np, "name", &pdata->name);
pdata->ignore_pwm = of_property_read_bool(np, "skyworks,ignore-pwm");
@@ -217,7 +215,6 @@ static struct sky81452_bl_platform_data *sky81452_bl_parse_dt(
num_entry);
if (ret < 0) {
dev_err(dev, "led-sources node is invalid.\n");
- of_node_put(np);
return ERR_PTR(-EINVAL);
}
@@ -237,7 +234,6 @@ static struct sky81452_bl_platform_data *sky81452_bl_parse_dt(
if (ret < 0)
pdata->boost_current_limit = 2750;
- of_node_put(np);
return pdata;
}
#else
--
2.44.0
^^^
Please fix the subject line to be "backlight: <driver>: ...". I came
very close to deleting this patch without reading it ;-) .
On Fri, Apr 19, 2024 at 01:13:02AM +0530, Shresth Prasad wrote:
> diff --git a/drivers/video/backlight/sky81452-backlight.c b/drivers/video/backlight/sky81452-backlight.c
> index eb18c6eb0ff0..3c5d8125080c 100644
> --- a/drivers/video/backlight/sky81452-backlight.c
> +++ b/drivers/video/backlight/sky81452-backlight.c
> @@ -182,7 +182,7 @@ static const struct attribute_group sky81452_bl_attr_group = {
> static struct sky81452_bl_platform_data *sky81452_bl_parse_dt(
> struct device *dev)
> {
> - struct device_node *np = of_node_get(dev->of_node);
> + struct device_node *np __free(device_node) = of_node_get(dev->of_node);
Do we need to get dev->of_node at all? The device, which we are
borrowing, already owns a reference to the node so I don't see
any point in this function taking an extra one.
So why not simply make this:
struct device_node *np = dev->of_node;
Daniel.
> Please fix the subject line to be "backlight: <driver>: ...". I came
> very close to deleting this patch without reading it ;-) .
Really sorry about that, I'll fix it.
> Do we need to get dev->of_node at all? The device, which we are
> borrowing, already owns a reference to the node so I don't see
> any point in this function taking an extra one.
>
> So why not simply make this:
>
> struct device_node *np = dev->of_node;
Looking at it again, I'm not sure why the call to `of_node_put` is there in the first place. I think removing it will be fine.
I'll fix both of these issues and send a patch v2.
Regards,
Shresth
On Sat, Apr 20, 2024 at 12:22:41AM +0530, Shresth Prasad wrote:
>
> > Please fix the subject line to be "backlight: <driver>: ...". I came
> > very close to deleting this patch without reading it ;-) .
>
> Really sorry about that, I'll fix it.
>
> > Do we need to get dev->of_node at all? The device, which we are
> > borrowing, already owns a reference to the node so I don't see
> > any point in this function taking an extra one.
> >
> > So why not simply make this:
> >
> > ??? struct device_node *np = dev->of_node;
>
> Looking at it again, I'm not sure why the call to `of_node_put` is there in the first place. I think removing it will be fine.
>
> I'll fix both of these issues and send a patch v2.
Just a stupid quesiton: on which platform was this patch tested?
--
With best wishes
Dmitry
20 Apr 2024 1:13:42 am Dmitry Baryshkov <[email protected]>:
> On Sat, Apr 20, 2024 at 12:22:41AM +0530, Shresth Prasad wrote:
>>
>>> Please fix the subject line to be "backlight: <driver>: ...". I came
>>> very close to deleting this patch without reading it ;-) .
>>
>> Really sorry about that, I'll fix it.
>>
>>> Do we need to get dev->of_node at all? The device, which we are
>>> borrowing, already owns a reference to the node so I don't see
>>> any point in this function taking an extra one.
>>>
>>> So why not simply make this:
>>>
>>> struct device_node *np = dev->of_node;
>>
>> Looking at it again, I'm not sure why the call to `of_node_put` is there in the first place. I think removing it will be fine.
>>
>> I'll fix both of these issues and send a patch v2.
>
> Just a stupid quesiton: on which platform was this patch tested?
>
> --
> With best wishes
> Dmitry
I tested the patch on a x86_64 qemu virtual machine
Regards,
Shresth