linux-kernel - Re: [PATCH 2/3] media: iris: Document difference in size during allocation

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Message-ID: <20251203091649.GA13064@pendragon.ideasonboard.com>
Date: Wed, 3 Dec 2025 18:16:49 +0900
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Ricardo Ribalda <ribalda@...omium.org>
Cc: Keke Li <keke.li@...ogic.com>,
	Jacopo Mondi <jacopo.mondi@...asonboard.com>,
	Daniel Scally <dan.scally@...asonboard.com>,
	Hans Verkuil <hverkuil+cisco@...nel.org>,
	Vikash Garodia <vikash.garodia@....qualcomm.com>,
	Dikshita Agarwal <dikshita.agarwal@....qualcomm.com>,
	Abhinav Kumar <abhinav.kumar@...ux.dev>,
	Bryan O'Donoghue <bod@...nel.org>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Sakari Ailus <sakari.ailus@...ux.intel.com>,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH 2/3] media: iris: Document difference in size during
 allocation

On Wed, Dec 03, 2025 at 08:55:35AM +0000, Ricardo Ribalda wrote:
> As we get ready for kzalloc checking for invalid sizes, let's add
> documentation for the cases where the size is different but valid.
> 
> This patch fixes this cocci warning:
> ./platform/qcom/iris/iris_hfi_gen2_command.c:1215:9-25: WARNING: casting value returned by memory allocation function to (struct iris_inst *) is useless.
> 
> Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
> ---
>  drivers/media/platform/qcom/iris/iris_hfi_gen2_command.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/platform/qcom/iris/iris_hfi_gen2_command.c b/drivers/media/platform/qcom/iris/iris_hfi_gen2_command.c
> index f9129553209922fda548ca320494ae6ae797854c..ab91afd0597045bd876d0411b08b5a3421b12c70 100644
> --- a/drivers/media/platform/qcom/iris/iris_hfi_gen2_command.c
> +++ b/drivers/media/platform/qcom/iris/iris_hfi_gen2_command.c
> @@ -1212,5 +1212,13 @@ void iris_hfi_gen2_command_ops_init(struct iris_core *core)
>  
>  struct iris_inst *iris_hfi_gen2_get_instance(void)
>  {
> -	return (struct iris_inst *)kzalloc(sizeof(struct iris_inst_hfi_gen2), GFP_KERNEL);
> +	struct iris_inst_hfi_gen2 *out;
> +
> +	/*
> +	 * The allocation is intentionally larger. The first member of
> +	 * struct iris_hfi_gen2 is struct iris_inst.
> +	 */
> +	out = kzalloc(sizeof(*out), GFP_KERNEL);
> +
> +	return (struct iris_inst *)out;

	return &out->inst;

would be more readable. You can then drop the comment.

>  }
> 

-- 
Regards,

Laurent Pinchart