Re: [PATCH] i2c: imx: Make sure to unregister adapter on remove()

From: Oleksij Rempel <o.rempel@pengutronix.de>
To: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: Oleksij Rempel <linux@rempel-privat.de>,
	Shawn Guo <shawnguo@kernel.org>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	NXP Linux Team <linux-imx@nxp.com>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	Fabio Estevam <festevam@gmail.com>,
	linux-arm-kernel@lists.infradead.org, linux-i2c@vger.kernel.org
Subject: Re: [PATCH] i2c: imx: Make sure to unregister adapter on remove()
Date: Fri, 29 Jul 2022 06:29:22 +0200	[thread overview]
Message-ID: <20220729042922.GD30201@pengutronix.de> (raw)
In-Reply-To: <20220720150933.239956-1-u.kleine-koenig@pengutronix.de>

Hi Uwe,

thank you for your work.

On Wed, Jul 20, 2022 at 05:09:33PM +0200, Uwe Kleine-König wrote:
> If for whatever reasons pm_runtime_resume_and_get() fails and .remove() is
> exited early, the i2c adapter stays around and the irq still calls its
> handler, while the driver data and the register mapping go away. So if
> later the i2c adapter is accessed or the irq triggers this results in
> havoc accessing freed memory and unmapped registers.
> 
> So unregister the software resources even if resume failed, and only skip
> the hardware access in that case.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Can you please add Fixes tag. I assume this patch can got to stable
kernel version too.

Otherwise:
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>

> ---
>  drivers/i2c/busses/i2c-imx.c | 20 +++++++++++---------
>  1 file changed, 11 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> index e9e2db68b9fb..7395560c13d0 100644
> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -1572,9 +1572,7 @@ static int i2c_imx_remove(struct platform_device *pdev)
>  	struct imx_i2c_struct *i2c_imx = platform_get_drvdata(pdev);
>  	int irq, ret;
>  
> -	ret = pm_runtime_resume_and_get(&pdev->dev);
> -	if (ret < 0)
> -		return ret;
> +	ret = pm_runtime_get_sync(&pdev->dev);
>  
>  	hrtimer_cancel(&i2c_imx->slave_timer);
>  
> @@ -1585,17 +1583,21 @@ static int i2c_imx_remove(struct platform_device *pdev)
>  	if (i2c_imx->dma)
>  		i2c_imx_dma_free(i2c_imx);
>  
> -	/* setup chip registers to defaults */
> -	imx_i2c_write_reg(0, i2c_imx, IMX_I2C_IADR);
> -	imx_i2c_write_reg(0, i2c_imx, IMX_I2C_IFDR);
> -	imx_i2c_write_reg(0, i2c_imx, IMX_I2C_I2CR);
> -	imx_i2c_write_reg(0, i2c_imx, IMX_I2C_I2SR);
> +	if (ret == 0) {
> +		/* setup chip registers to defaults */
> +		imx_i2c_write_reg(0, i2c_imx, IMX_I2C_IADR);
> +		imx_i2c_write_reg(0, i2c_imx, IMX_I2C_IFDR);
> +		imx_i2c_write_reg(0, i2c_imx, IMX_I2C_I2CR);
> +		imx_i2c_write_reg(0, i2c_imx, IMX_I2C_I2SR);
> +		clk_disable(i2c_imx->clk);
> +	}
>  
>  	clk_notifier_unregister(i2c_imx->clk, &i2c_imx->clk_change_nb);
>  	irq = platform_get_irq(pdev, 0);
>  	if (irq >= 0)
>  		free_irq(irq, i2c_imx);
> -	clk_disable_unprepare(i2c_imx->clk);
> +
> +	clk_unprepare(i2c_imx->clk);
>  
>  	pm_runtime_put_noidle(&pdev->dev);
>  	pm_runtime_disable(&pdev->dev);
> 
> base-commit: 6014cfa5bf32cf8c5c58b3cfd5ee0e1542c8a825
> -- 
> 2.36.1
> 
> 
> 

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |