linux-kernel - Re: [PATCH 0/2] fix fwnode_irq_get

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Message-ID: <Y1eqWbyJLlEW5Mdo@smile.fi.intel.com>
Date:   Tue, 25 Oct 2022 12:20:25 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Matti Vaittinen <mazziesaccount@...il.com>
Cc:     Matti Vaittinen <matti.vaittinen@...rohmeurope.com>,
        Daniel Scally <djrscally@...il.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Wolfram Sang <wsa@...nel.org>,
        Akhil R <akhilrajeev@...dia.com>, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-i2c@...r.kernel.org
Subject: Re: [PATCH 0/2] fix fwnode_irq_get_byname() returnvalue

On Tue, Oct 25, 2022 at 11:50:24AM +0300, Matti Vaittinen wrote:
> The fix fwnode_irq_get_byname() may have returned zero if mapping the
> IRQ fails. This contradicts the documentation. Furthermore, returning
> zero or errno on error is unepected and can easily lead to problems
> like:
> 
> int probe(foo)
> {
> ...
> 	ret = fwnode_irq_get_byname(...);
> 	if (ret < 0)
> 		return ret;
> ...
> }
> 
> or
> 
> int probe(foo)
> {
> ...
> 	ret = fwnode_irq_get_byname(...);
> 	if (ret <= 0)
> 		return ret;
> ...
> }
> 
> which are both likely to be wrong. First treats zero as successful call and
> misses the IRQ mapping failure. Second returns zero from probe even though
> it detects the IRQ mapping failure correvtly.
> 
> Here we change the fwnode_irq_get_byname() to always return a negative
> errno upon failure. I have also audited following callers:
> 
> drivers/i2c/i2c-smbus.c
> drivers/iio/accel/adxl355_core.c
> drivers/iio/gyro/fxas21002c_core.c
> drivers/iio/imu/adis16480.c
> drivers/iio/imu/bmi160/bmi160_core.c
> drivers/iio/imu/bmi160/bmi160_core.c
> 
> and it seems to me these calls will be Ok after the change. The
> i2c-smbus.c will gain a functional change (bugfix?) as after this patch
> the probe will return -EINVAL should the IRQ mapping fail. The series
> will also adjust the return value check for zero to be omitted.

Thanks for doing this, no major comments except worrying about fwnode_irq_get()
which is left untouched an hence different error domain for the same
family of API.

For these patches:
Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>


-- 
With Best Regards,
Andy Shevchenko