linux-kernel - Re: [RESEND PATCH v5 1/5] driver core: add probe

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Date:   Wed, 24 Jun 2020 16:04:38 +0200
From:   Andrzej Hajda <a.hajda@...sung.com>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Jernej Skrabec <jernej.skrabec@...l.net>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Jonas Karlman <jonas@...boo.se>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        linux-kernel@...r.kernel.org,
        "open list:DRM DRIVERS" <dri-devel@...ts.freedesktop.org>,
        Russell King - ARM Linux <linux@...linux.org.uk>,
        Neil Armstrong <narmstrong@...libre.com>,
        andy.shevchenko@...il.com, Mark Brown <broonie@...nel.org>,
        linux-arm-kernel@...ts.infradead.org,
        Marek Szyprowski <m.szyprowski@...sung.com>
Subject: Re: [RESEND PATCH v5 1/5] driver core: add probe_err log helper


On 24.06.2020 15:23, Laurent Pinchart wrote:
> On Wed, Jun 24, 2020 at 02:31:40PM +0200, Greg Kroah-Hartman wrote:
>> On Wed, Jun 24, 2020 at 01:41:23PM +0200, Andrzej Hajda wrote:
>>> During probe every time driver gets resource it should usually check for error
>>> printk some message if it is not -EPROBE_DEFER and return the error. This
>>> pattern is simple but requires adding few lines after any resource acquisition
>>> code, as a result it is often omited or implemented only partially.
>>> probe_err helps to replace such code sequences with simple call, so code:
>>> 	if (err != -EPROBE_DEFER)
>>> 		dev_err(dev, ...);
>>> 	return err;
>>> becomes:
>>> 	return probe_err(dev, err, ...);
>>>
>>> Signed-off-by: Andrzej Hajda <a.hajda@...sung.com>
>>> Reviewed-by: Javier Martinez Canillas <javierm@...hat.com>
>>> Reviewed-by: Mark Brown <broonie@...nel.org>
>>> Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
>>> ---
>>>   drivers/base/core.c    | 39 +++++++++++++++++++++++++++++++++++++++
>>>   include/linux/device.h |  3 +++
>>>   2 files changed, 42 insertions(+)
>>>
>>> diff --git a/drivers/base/core.c b/drivers/base/core.c
>>> index 67d39a90b45c..ee9da66bff1b 100644
>>> --- a/drivers/base/core.c
>>> +++ b/drivers/base/core.c
>>> @@ -3953,6 +3953,45 @@ define_dev_printk_level(_dev_info, KERN_INFO);
>>>   
>>>   #endif
>>>   
>>> +/**
>>> + * probe_err - probe error check and log helper
>>> + * @dev: the pointer to the struct device
>>> + * @err: error value to test
>>> + * @fmt: printf-style format string
>>> + * @...: arguments as specified in the format string
>>> + *
>>> + * This helper implements common pattern present in probe functions for error
>>> + * checking: print message if the error is not -EPROBE_DEFER and propagate it.
>>> + * It replaces code sequence:
>>> + * 	if (err != -EPROBE_DEFER)
>>> + * 		dev_err(dev, ...);
>>> + * 	return err;
>>> + * with
>>> + * 	return probe_err(dev, err, ...);
>>> + *
>>> + * Returns @err.
>>> + *
>>> + */
>>> +int probe_err(const struct device *dev, int err, const char *fmt, ...)
>>> +{
>>> +	struct va_format vaf;
>>> +	va_list args;
>>> +
>>> +	if (err == -EPROBE_DEFER)
>>> +		return err;
>>> +
>>> +	va_start(args, fmt);
>>> +	vaf.fmt = fmt;
>>> +	vaf.va = &args;
>>> +
>>> +	dev_err(dev, "error %d: %pV", err, &vaf);
>>> +
>>> +	va_end(args);
>>> +
>>> +	return err;
>>> +}
>>> +EXPORT_SYMBOL_GPL(probe_err);
>> Please be specific in global symbols, how about "driver_probe_error()"?
> Or dev_err_probe() to match the existing dev_* functions ?


OK.


Regards

Andrzej


>
>> And merge the other patch into this one, as Raphael said, otherwise this
>> just looks odd to add something and then fix it up later.