Re: [PATCH for-5.10] spi: mt7621: Don't leak SPI master in probe error path

[Stefan Roese <sr@denx.de>]

On 16.11.20 09:23, Lukas Wunner wrote:
> If the calls to device_reset() or devm_spi_register_controller() fail on
> probe of the MediaTek MT7621 SPI driver, the spi_controller struct is
> erroneously not freed.  Fix by switching over to the new
> devm_spi_alloc_master() helper.
> 
> Moreover, the SYS clock is enabled on probe but not disabled if any of
> the subsequent probe steps fails.
> 
> Finally, there's an ordering issue in mt7621_spi_remove() wherein
> the spi_controller is unregistered after disabling the SYS clock.
> The correct order is to call spi_unregister_controller() *before* this
> teardown step because bus accesses may still be ongoing until that
> function returns.
> 
> All of these bugs have existed since the driver was first introduced,
> so it seems fair to fix them together in a single commit.
> 
> Fixes: 1ab7f2a43558 ("staging: mt7621-spi: add mt7621 support")
> Signed-off-by: Lukas Wunner <lukas@wunner.de>
> Cc: <stable@vger.kernel.org> # v4.17+: 5e844cc37a5c: spi: Introduce device-managed SPI controller allocation
> Cc: <stable@vger.kernel.org> # v4.17+

Reviewed-by: Stefan Roese <sr@denx.de>

Thanks,
Stefan

> ---
>   drivers/spi/spi-mt7621.c | 18 ++++++++++++++----
>   1 file changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/spi/spi-mt7621.c b/drivers/spi/spi-mt7621.c
> index 2c3b7a2a1ec7..d7cda66c4b26 100644
> --- a/drivers/spi/spi-mt7621.c
> +++ b/drivers/spi/spi-mt7621.c
> @@ -350,10 +350,11 @@ static int mt7621_spi_probe(struct platform_device *pdev)
>   	if (status)
>   		return status;
>   
> -	master = spi_alloc_master(&pdev->dev, sizeof(*rs));
> +	master = devm_spi_alloc_master(&pdev->dev, sizeof(*rs));
>   	if (!master) {
>   		dev_info(&pdev->dev, "master allocation failed\n");
> -		return -ENOMEM;
> +		ret = -ENOMEM;
> +		goto err_clk_disable;
>   	}
>   
>   	master->mode_bits = SPI_LSB_FIRST;
> @@ -377,10 +378,18 @@ static int mt7621_spi_probe(struct platform_device *pdev)
>   	ret = device_reset(&pdev->dev);
>   	if (ret) {
>   		dev_err(&pdev->dev, "SPI reset failed!\n");
> -		return ret;
> +		goto err_clk_disable;
>   	}
>   
> -	return devm_spi_register_controller(&pdev->dev, master);
> +	ret = spi_register_controller(master);
> +	if (ret)
> +		goto err_clk_disable;
> +
> +	return 0;
> +
> +err_clk_disable:
> +	clk_disable_unprepare(clk);
> +	return ret;
>   }
>   
>   static int mt7621_spi_remove(struct platform_device *pdev)
> @@ -391,6 +400,7 @@ static int mt7621_spi_remove(struct platform_device *pdev)
>   	master = dev_get_drvdata(&pdev->dev);
>   	rs = spi_controller_get_devdata(master);
>   
> +	spi_unregister_controller(master);
>   	clk_disable_unprepare(rs->clk);
>   
>   	return 0;
>