linux-kernel - Re: [PATCH] drm/vc4: remove all usages of of_node

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Date: Tue, 18 Jun 2024 13:54:15 +0200
From: Amer Al Shanawany <amer.shanawany@...il.com>
To: Maxime Ripard <mripard@...nel.org>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>,
 Daniel Vetter <daniel@...ll.ch>, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org
Cc: Julia Lawall <julia.lawall@...ia.fr>, Shuah Khan <shuah@...nel.org>,
 Javier Carrasco <javier.carrasco.cruz@...il.com>
Subject: Re: [PATCH] drm/vc4: remove all usages of of_node_put()

On 5/22/24 16:48, Amer Al Shanawany wrote:
> On 27/04/2024 15.40, Amer Al Shanawany wrote:
>> Use the scope-based cleanup feature to clean up 'struct device_node *'
>> when they go out of scope, and remove all instances of of_node_put()
>> within the same scope, to simplify function exit and avoid potential
>> memory leaks.
>>
>> Suggested-by: Julia Lawall <julia.lawall@...ia.fr>
>> Signed-off-by: Amer Al Shanawany <amer.shanawany@...il.com>
>> ---
>>   drivers/gpu/drm/vc4/vc4_drv.c  | 14 ++++++--------
>>   drivers/gpu/drm/vc4/vc4_hdmi.c |  4 +---
>>   drivers/gpu/drm/vc4/vc4_hvs.c  |  4 +---
>>   3 files changed, 8 insertions(+), 14 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/vc4/vc4_drv.c b/drivers/gpu/drm/vc4/vc4_drv.c
>> index c133e96b8aca..bb0bb052e595 100644
>> --- a/drivers/gpu/drm/vc4/vc4_drv.c
>> +++ b/drivers/gpu/drm/vc4/vc4_drv.c
>> @@ -289,7 +289,6 @@ static int vc4_drm_bind(struct device *dev)
>>       struct rpi_firmware *firmware = NULL;
>>       struct drm_device *drm;
>>       struct vc4_dev *vc4;
>> -    struct device_node *node;
>>       struct drm_crtc *crtc;
>>       bool is_vc5;
>>       int ret = 0;
>> @@ -302,11 +301,10 @@ static int vc4_drm_bind(struct device *dev)
>>       else
>>           driver = &vc4_drm_driver;
>>   -    node = of_find_matching_node_and_match(NULL, vc4_dma_range_matches,
>> -                           NULL);
>> +    struct device_node *node __free(device_node) =
>> +        of_find_matching_node_and_match(NULL, vc4_dma_range_matches, NULL);
>>       if (node) {
>>           ret = of_dma_configure(dev, node, true);
>> -        of_node_put(node);
>>             if (ret)
>>               return ret;
>> @@ -341,10 +339,10 @@ static int vc4_drm_bind(struct device *dev)
>>               goto err;
>>       }
>>   -    node = of_find_compatible_node(NULL, NULL, "raspberrypi,bcm2835-firmware");
>> -    if (node) {
>> -        firmware = rpi_firmware_get(node);
>> -        of_node_put(node);
>> +    struct device_node *np __free(device_node) =
>> +        of_find_compatible_node(NULL, NULL, "raspberrypi,bcm2835-firmware");
>> +    if (np) {
>> +        firmware = rpi_firmware_get(np);
>>             if (!firmware) {
>>               ret = -EPROBE_DEFER;
>> diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
>> index d30f8e8e8967..915e8da3f41a 100644
>> --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
>> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
>> @@ -3661,7 +3661,6 @@ static int vc4_hdmi_bind(struct device *dev, struct device *master, void *data)
>>       struct drm_device *drm = dev_get_drvdata(master);
>>       struct vc4_hdmi *vc4_hdmi;
>>       struct drm_encoder *encoder;
>> -    struct device_node *ddc_node;
>>       int ret;
>>         vc4_hdmi = drmm_kzalloc(drm, sizeof(*vc4_hdmi), GFP_KERNEL);
>> @@ -3699,14 +3698,13 @@ static int vc4_hdmi_bind(struct device *dev, struct device *master, void *data)
>>       if (ret)
>>           return ret;
>>   -    ddc_node = of_parse_phandle(dev->of_node, "ddc", 0);
>> +    struct device_node *ddc_node __free(device_node) = of_parse_phandle(dev->of_node, "ddc", 0);
>>       if (!ddc_node) {
>>           DRM_ERROR("Failed to find ddc node in device tree\n");
>>           return -ENODEV;
>>       }
>>         vc4_hdmi->ddc = of_find_i2c_adapter_by_node(ddc_node);
>> -    of_node_put(ddc_node);
>>       if (!vc4_hdmi->ddc) {
>>           DRM_DEBUG("Failed to get ddc i2c adapter by node\n");
>>           return -EPROBE_DEFER;
>> diff --git a/drivers/gpu/drm/vc4/vc4_hvs.c b/drivers/gpu/drm/vc4/vc4_hvs.c
>> index 04af672caacb..6e3613e06e09 100644
>> --- a/drivers/gpu/drm/vc4/vc4_hvs.c
>> +++ b/drivers/gpu/drm/vc4/vc4_hvs.c
>> @@ -845,15 +845,13 @@ static int vc4_hvs_bind(struct device *dev, struct device *master, void *data)
>>         if (vc4->is_vc5) {
>>           struct rpi_firmware *firmware;
>> -        struct device_node *node;
>> +        struct device_node *node __free(device_node) = rpi_firmware_find_node();
>>           unsigned int max_rate;
>>   -        node = rpi_firmware_find_node();
>>           if (!node)
>>               return -EINVAL;
>>             firmware = rpi_firmware_get(node);
>> -        of_node_put(node);
>>           if (!firmware)
>>               return -EPROBE_DEFER;
>>   
> Hi,
>
> This patch is marked as new/archived on patchwork[1], however it didn't receive any feedback, and a similar patch has been already merged [2].
>
>
> [1]: https://patchwork.kernel.org/project/dri-devel/patch/20240427134044.38910-1-amer.shanawany@gmail.com/
>
> [2]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d65bfb9546eb627e3c578336355c5b81797f2255
>
> Thank you
>
> Amer
>
Hello,

Could anyone kindly provide some feedback on this patch?

Thank you

Amer