linux-kernel - Re: [PATCH linux-next] media:cdns-csi2tx: replace of_node_put() with _

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Message-ID: <80aaad79-9426-4ee4-afe9-a10c089df086@gmail.com>
Date: Wed, 1 May 2024 09:01:34 +0530
From: R Sundar <prosunofficial@...il.com>
To: Julia Lawall <julia.lawall@...ia.fr>
Cc: Christophe JAILLET <christophe.jaillet@...adoo.fr>, mripard@...nel.org,
 mchehab@...nel.org, linux-media@...r.kernel.org,
 linux-kernel@...r.kernel.org, skhan@...uxfoundation.org,
 javier.carrasco.cruz@...il.com
Subject: Re: [PATCH linux-next] media:cdns-csi2tx: replace of_node_put() with
 __free

On 30/04/24 22:53, Julia Lawall wrote:
> 
> 
> On Tue, 30 Apr 2024, R Sundar wrote:
> 
>> On 30/04/24 00:10, Christophe JAILLET wrote:
>>> Le 29/04/2024 à 19:15, R Sundar a écrit :
>>>> Use the new cleanup magic to replace of_node_put() with
>>>> __free(device_node) marking to auto release when they get out of scope.
>>>>
>>>> Suggested-by: Julia Lawall <julia.lawall@...ia.fr>
>>>> Signed-off-by: R Sundar <prosunofficial@...il.com>
>>>> ---
>>>>    drivers/media/platform/cadence/cdns-csi2tx.c | 19 +++++++------------
>>>>    1 file changed, 7 insertions(+), 12 deletions(-)
>>>>
>>>> diff --git a/drivers/media/platform/cadence/cdns-csi2tx.c
>>>> b/drivers/media/platform/cadence/cdns-csi2tx.c
>>>> index 3d98f91f1bee..88aed2f299fd 100644
>>>> --- a/drivers/media/platform/cadence/cdns-csi2tx.c
>>>> +++ b/drivers/media/platform/cadence/cdns-csi2tx.c
>>>> @@ -496,48 +496,43 @@ static int csi2tx_get_resources(struct csi2tx_priv
>>>> *csi2tx,
>>>>    static int csi2tx_check_lanes(struct csi2tx_priv *csi2tx)
>>>>    {
>>>>        struct v4l2_fwnode_endpoint v4l2_ep = { .bus_type = 0 };
>>>> -    struct device_node *ep;
>>>>        int ret, i;
>>>> -
>>>> -    ep = of_graph_get_endpoint_by_regs(csi2tx->dev->of_node, 0, 0);
>>>> +    struct device_node *ep __free(device_node) =
>>>> +        of_graph_get_endpoint_by_regs(csi2tx->dev->of_node, 0, 0);
>>>> +
>>>>        if (!ep)
>>>>            return -EINVAL;
>>>>        ret = v4l2_fwnode_endpoint_parse(of_fwnode_handle(ep), &v4l2_ep);
>>>>        if (ret) {
>>>>            dev_err(csi2tx->dev, "Could not parse v4l2 endpoint\n");
>>>> -        goto out;
>>>> +        return ret;
>>>>        }
>>>>        if (v4l2_ep.bus_type != V4L2_MBUS_CSI2_DPHY) {
>>>>            dev_err(csi2tx->dev, "Unsupported media bus type: 0x%x\n",
>>>>                v4l2_ep.bus_type);
>>>> -        ret = -EINVAL;
>>>> -        goto out;
>>>> +        return -EINVAL;
>>>>        }
>>>>        csi2tx->num_lanes = v4l2_ep.bus.mipi_csi2.num_data_lanes;
>>>>        if (csi2tx->num_lanes > csi2tx->max_lanes) {
>>>>            dev_err(csi2tx->dev,
>>>>                "Current configuration uses more lanes than supported\n");
>>>> -        ret = -EINVAL;
>>>> -        goto out;
>>>> +        return -EINVAL;
>>>>        }
>>>>        for (i = 0; i < csi2tx->num_lanes; i++) {
>>>>            if (v4l2_ep.bus.mipi_csi2.data_lanes[i] < 1) {
>>>>                dev_err(csi2tx->dev, "Invalid lane[%d] number: %u\n",
>>>>                    i, v4l2_ep.bus.mipi_csi2.data_lanes[i]);
>>>> -            ret = -EINVAL;
>>>> -            goto out;
>>>> +            return -EINVAL;
>>>>            }
>>>>        }
>>>>        memcpy(csi2tx->lanes, v4l2_ep.bus.mipi_csi2.data_lanes,
>>>>               sizeof(csi2tx->lanes));
>>>> -out:
>>>> -    of_node_put(ep);
>>>>        return ret;
>>>
>>> Hi,
>>>
>>> Nit: return 0; ?
>>>
>>> CJ
>>>
>>>>    }
>>>
>> Hi,
>>
>> In success case, ret variable value also will be zero, else for non-zero ret
>> value it will return from v4l2_fwnode_endpoint_parse()'s error case handling
>> block.
> 
> Indeed, but it seems that the return ret at the end of the function always
> returns 0?  If that is the case, return 0 would be better, as one can see
> that that code is only reached in the success case.
> 
> julia

Hi Julia,

Noted.

@CJ, Thanks for comments.  Understood the point of Nit.

Will update the changes.

Thanks,
Sundar