Re: [PATCH v3] i2c: imx: Fix external abort on interrupt in exit paths

[Oleksij Rempel]

On Sun, Sep 20, 2020 at 11:12:38PM +0200, Krzysztof Kozlowski wrote:
> If interrupt comes late, during probe error path or device remove (could
> be triggered with CONFIG_DEBUG_SHIRQ), the interrupt handler
> i2c_imx_isr() will access registers with the clock being disabled.  This
> leads to external abort on non-linefetch on Toradex Colibri VF50 module
> (with Vybrid VF5xx):
> 
>     Unhandled fault: external abort on non-linefetch (0x1008) at 0x8882d003
>     Internal error: : 1008 [#1] ARM
>     Modules linked in:
>     CPU: 0 PID: 1 Comm: swapper Not tainted 5.7.0 #607
>     Hardware name: Freescale Vybrid VF5xx/VF6xx (Device Tree)
>       (i2c_imx_isr) from [<8017009c>] (free_irq+0x25c/0x3b0)
>       (free_irq) from [<805844ec>] (release_nodes+0x178/0x284)
>       (release_nodes) from [<80580030>] (really_probe+0x10c/0x348)
>       (really_probe) from [<80580380>] (driver_probe_device+0x60/0x170)
>       (driver_probe_device) from [<80580630>] (device_driver_attach+0x58/0x60)
>       (device_driver_attach) from [<805806bc>] (__driver_attach+0x84/0xc0)
>       (__driver_attach) from [<8057e228>] (bus_for_each_dev+0x68/0xb4)
>       (bus_for_each_dev) from [<8057f3ec>] (bus_add_driver+0x144/0x1ec)
>       (bus_add_driver) from [<80581320>] (driver_register+0x78/0x110)
>       (driver_register) from [<8010213c>] (do_one_initcall+0xa8/0x2f4)
>       (do_one_initcall) from [<80c0100c>] (kernel_init_freeable+0x178/0x1dc)
>       (kernel_init_freeable) from [<80807048>] (kernel_init+0x8/0x110)
>       (kernel_init) from [<80100114>] (ret_from_fork+0x14/0x20)
> 
> Additionally, the i2c_imx_isr() could wake up the wait queue
> (imx_i2c_struct->queue) before its initialization happens.
> 
> The resource-managed framework should not be used for interrupt handling,
> because the resource will be released too late - after disabling clocks.
> The interrupt handler is not prepared for such case.
> 
> Fixes: 1c4b6c3bcf30 ("i2c: imx: implement bus recovery")
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Krzysztof Kozlowski <krzk@xxxxxxxxxx>

Acked-by: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>

Thank you!

> ---
> 
> Changes since v2:
> 1. Rebase
> 
> Changes since v1:
> 1. Remove the devm- and use regular methods.
> ---
>  drivers/i2c/busses/i2c-imx.c | 24 +++++++++++++-----------
>  1 file changed, 13 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> index 63f4367c312b..c98529c76348 100644
> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -1169,14 +1169,6 @@ static int i2c_imx_probe(struct platform_device *pdev)
>  		return ret;
>  	}
>  
> -	/* Request IRQ */
> -	ret = devm_request_irq(&pdev->dev, irq, i2c_imx_isr, IRQF_SHARED,
> -				pdev->name, i2c_imx);
> -	if (ret) {
> -		dev_err(&pdev->dev, "can't claim irq %d\n", irq);
> -		goto clk_disable;
> -	}
> -
>  	/* Init queue */
>  	init_waitqueue_head(&i2c_imx->queue);
>  
> @@ -1195,6 +1187,14 @@ static int i2c_imx_probe(struct platform_device *pdev)
>  	if (ret < 0)
>  		goto rpm_disable;
>  
> +	/* Request IRQ */
> +	ret = request_threaded_irq(irq, i2c_imx_isr, NULL, IRQF_SHARED,
> +				   pdev->name, i2c_imx);
> +	if (ret) {
> +		dev_err(&pdev->dev, "can't claim irq %d\n", irq);
> +		goto rpm_disable;
> +	}
> +
>  	/* Set up clock divider */
>  	i2c_imx->bitrate = I2C_MAX_STANDARD_MODE_FREQ;
>  	ret = of_property_read_u32(pdev->dev.of_node,
> @@ -1237,13 +1237,12 @@ static int i2c_imx_probe(struct platform_device *pdev)
>  
>  clk_notifier_unregister:
>  	clk_notifier_unregister(i2c_imx->clk, &i2c_imx->clk_change_nb);
> +	free_irq(irq, i2c_imx);
>  rpm_disable:
>  	pm_runtime_put_noidle(&pdev->dev);
>  	pm_runtime_disable(&pdev->dev);
>  	pm_runtime_set_suspended(&pdev->dev);
>  	pm_runtime_dont_use_autosuspend(&pdev->dev);
> -
> -clk_disable:
>  	clk_disable_unprepare(i2c_imx->clk);
>  	return ret;
>  }
> @@ -1251,7 +1250,7 @@ static int i2c_imx_probe(struct platform_device *pdev)
>  static int i2c_imx_remove(struct platform_device *pdev)
>  {
>  	struct imx_i2c_struct *i2c_imx = platform_get_drvdata(pdev);
> -	int ret;
> +	int irq, ret;
>  
>  	ret = pm_runtime_get_sync(&pdev->dev);
>  	if (ret < 0)
> @@ -1271,6 +1270,9 @@ static int i2c_imx_remove(struct platform_device *pdev)
>  	imx_i2c_write_reg(0, i2c_imx, IMX_I2C_I2SR);
>  
>  	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);
>  
>  	pm_runtime_put_noidle(&pdev->dev);
> -- 
> 2.17.1
> 
> 
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> 

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