linux-kernel - Re: [PATCH 3/4] rtc: isl1208: enable interrupt after context preparation

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Date:   Tue, 30 Jan 2018 11:34:21 +0100
From:   Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To:     Michael Grzeschik <m.grzeschik@...gutronix.de>
Cc:     a.zummo@...ertech.it, linux-rtc@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux@...ck-us.net, jdelvare@...e.com, kernel@...gutronix.de,
        Denis.Osterland@...hl.com
Subject: Re: [PATCH 3/4] rtc: isl1208: enable interrupt after context
 preparation

Hi,

On 23/01/2018 at 13:18:00 +0100, Michael Grzeschik wrote:
> The interrupt handler got enabled very early. If the interrupt cause is
> triggering immediately before the context is fully prepared. This can
> lead to undefined behaviour. Therefor we move the interrupt enable code
> to the end of the probe function.
> 

Can you fix it using devm_rtc_allocate_device()/rtc_register_device() as
done in https://git.kernel.org/pub/scm/linux/kernel/git/abelloni/linux.git/commit/?h=rtc-next&id=994ec64c0a193940be7a6fd074668b9446d3b6c3

> Signed-off-by: Michael Grzeschik <m.grzeschik@...gutronix.de>
> Signed-off-by: Denis Osterland <Denis.Osterland@...hl.com>
> ---
>  drivers/rtc/rtc-isl1208.c | 34 +++++++++++++++++-----------------
>  1 file changed, 17 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/rtc/rtc-isl1208.c b/drivers/rtc/rtc-isl1208.c
> index c8b4953482296..a13a4ba79004d 100644
> --- a/drivers/rtc/rtc-isl1208.c
> +++ b/drivers/rtc/rtc-isl1208.c
> @@ -635,23 +635,6 @@ isl1208_probe(struct i2c_client *client, const struct i2c_device_id *id)
>  	if (isl1208_i2c_validate_client(client) < 0)
>  		return -ENODEV;
>  
> -	if (client->irq > 0) {
> -		rc = devm_request_threaded_irq(&client->dev, client->irq, NULL,
> -					       isl1208_rtc_interrupt,
> -					       IRQF_SHARED | IRQF_ONESHOT,
> -					       isl1208_driver.driver.name,
> -					       client);
> -		if (!rc) {
> -			device_init_wakeup(&client->dev, 1);
> -			enable_irq_wake(client->irq);
> -		} else {
> -			dev_err(&client->dev,
> -				"Unable to request irq %d, no alarm support\n",
> -				client->irq);
> -			client->irq = 0;
> -		}
> -	}
> -
>  	rtc = devm_rtc_device_register(&client->dev, isl1208_driver.driver.name,
>  				  &isl1208_rtc_ops,
>  				  THIS_MODULE);
> @@ -674,6 +657,23 @@ isl1208_probe(struct i2c_client *client, const struct i2c_device_id *id)
>  	if (rc)
>  		return rc;
>  
> +	if (client->irq > 0) {
> +		rc = devm_request_threaded_irq(&client->dev, client->irq, NULL,
> +					       isl1208_rtc_interrupt,
> +					       IRQF_SHARED | IRQF_ONESHOT,
> +					       isl1208_driver.driver.name,
> +					       client);
> +		if (!rc) {
> +			device_init_wakeup(&client->dev, 1);
> +			enable_irq_wake(client->irq);
> +		} else {
> +			dev_err(&client->dev,
> +				"Unable to request irq %d, no alarm support\n",
> +				client->irq);
> +			client->irq = 0;
> +		}
> +	}
> +
>  	return 0;
>  }
>  
> -- 
> 2.11.0
> 

-- 
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com