linux-kernel - Re: [PATCH v2 25/61] mmc: f-sdh30: Convert to platform remove callback returning void

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Message-ID: <20230726065357.afriboprvkup5kiw@pengutronix.de>
Date:   Wed, 26 Jul 2023 08:53:57 +0200
From:   Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
To:     Yangtao Li <frank.li@...o.com>
Cc:     Adrian Hunter <adrian.hunter@...el.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 25/61] mmc: f-sdh30: Convert to platform remove
 callback returning void

On Wed, Jul 26, 2023 at 12:00:05PM +0800, Yangtao Li wrote:
> The .remove() callback for a platform driver returns an int which makes
> many driver authors wrongly assume it's possible to do error handling by
> returning an error code. However the value returned is (mostly) ignored
> and this typically results in resource leaks. To improve here there is a
> quest to make the remove callback return void. In the first step of this
> quest all drivers are converted to .remove_new() which already returns
> void.
> 
> Trivially convert this driver from always returning zero in the remove
> callback to the void returning variant.
> 
> Cc: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
> Signed-off-by: Yangtao Li <frank.li@...o.com>
> Acked-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
> ---
>  drivers/mmc/host/sdhci_f_sdh30.c | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/mmc/host/sdhci_f_sdh30.c b/drivers/mmc/host/sdhci_f_sdh30.c
> index b01ffb4d0973..840084ee72e6 100644
> --- a/drivers/mmc/host/sdhci_f_sdh30.c
> +++ b/drivers/mmc/host/sdhci_f_sdh30.c
> @@ -206,7 +206,7 @@ static int sdhci_f_sdh30_probe(struct platform_device *pdev)
>  	return ret;
>  }
>  
> -static int sdhci_f_sdh30_remove(struct platform_device *pdev)
> +static void sdhci_f_sdh30_remove(struct platform_device *pdev)
>  {
>  	struct sdhci_host *host = platform_get_drvdata(pdev);
>  	struct f_sdhost_priv *priv = sdhci_f_sdhost_priv(host);
> @@ -216,8 +216,6 @@ static int sdhci_f_sdh30_remove(struct platform_device *pdev)
>  	clk_disable_unprepare(priv->clk_iface);
>  
>  	sdhci_pltfm_unregister(pdev);
> -
> -	return 0;
>  }

While looking in more detail into this series I noticed a problem in
this driver. (The patch is fine, and so is my Ack.)

The order of function calls in sdhci_f_sdh30_remove is wrong. It first
reasserts the reset and disables clocks and only then unregisters the
sdhci-host which should stay functional until sdhci_remove_host() (called
by sdhci_pltfm_unregister()) completes.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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