linux-kernel - Re: [PATCH] coresight: etm4x: return 0 instead of using local ret variable

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Message-ID: <20220421164217.GB1596562@p14s>
Date:   Thu, 21 Apr 2022 10:42:17 -0600
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Shile Zhang <shile.zhang@...ux.alibaba.com>
Cc:     Suzuki K Poulose <suzuki.poulose@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] coresight: etm4x: return 0 instead of using local ret
 variable

Hi Shile,

On Wed, Apr 20, 2022 at 01:28:31PM +0800, Shile Zhang wrote:
> The etm4_remove function (now it's rename to etm4_remove_dev) always
> return 0, and it has been changed to void in commit 4fd269e74f2f
> ("amba: Make the remove callback return void"). But its weird that the
> changes is gone in mainline. which is remained in 5.10.y branch.

Commit 4fd269e74f2f is not valid upstream.  Changes that don't have a critical
impact on user experience or fix a bug aren't backported to longterm kernels. 

> 
> Just backport the changes of etm4_remove_dev and return 0 directly in it's
> caller function etm4_remove_platform_dev.

I'm not sure why the work "backport" is used here since this patch is destine
for mainline.

> 
> Signed-off-by: Shile Zhang <shile.zhang@...ux.alibaba.com>
> ---
>  drivers/hwtracing/coresight/coresight-etm4x-core.c | 11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> index 7f416a12000e..141f8209a152 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> @@ -2104,7 +2104,7 @@ static void clear_etmdrvdata(void *info)
>  	etmdrvdata[cpu] = NULL;
>  }
>  
> -static int __exit etm4_remove_dev(struct etmv4_drvdata *drvdata)
> +static void __exit etm4_remove_dev(struct etmv4_drvdata *drvdata)
>  {
>  	etm_perf_symlink(drvdata->csdev, false);
>  	/*
> @@ -2125,8 +2125,6 @@ static int __exit etm4_remove_dev(struct etmv4_drvdata *drvdata)
>  
>  	cscfg_unregister_csdev(drvdata->csdev);
>  	coresight_unregister(drvdata->csdev);
> -
> -	return 0;
>  }
>  
>  static void __exit etm4_remove_amba(struct amba_device *adev)
> @@ -2139,13 +2137,14 @@ static void __exit etm4_remove_amba(struct amba_device *adev)
>  
>  static int __exit etm4_remove_platform_dev(struct platform_device *pdev)
>  {
> -	int ret = 0;
>  	struct etmv4_drvdata *drvdata = dev_get_drvdata(&pdev->dev);
>  
>  	if (drvdata)
> -		ret = etm4_remove_dev(drvdata);
> +		etm4_remove_dev(drvdata);
> +
>  	pm_runtime_disable(&pdev->dev);
> -	return ret;
> +
> +	return 0;

I'm fine with the code but the changelog needs to be re-worked.  The only
rational for this patch is that the return value for function etm4_remove_dev()
is never used and as such being removed. 

Thanks,
Mathieu

>  }
>  
>  static const struct amba_id etm4_ids[] = {
> -- 
> 2.33.0.rc2
>