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

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Message-ID: <20200624132344.GA5980@pendragon.ideasonboard.com>
Date:   Wed, 24 Jun 2020 16:23:44 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Andrzej Hajda <a.hajda@...sung.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        andy.shevchenko@...il.com, Mark Brown <broonie@...nel.org>,
        Russell King - ARM Linux <linux@...linux.org.uk>,
        Neil Armstrong <narmstrong@...libre.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Daniel Vetter <daniel@...ll.ch>,
        "open list:DRM DRIVERS" <dri-devel@...ts.freedesktop.org>
Subject: Re: [RESEND PATCH v5 1/5] driver core: add probe_err log helper

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 ?

> 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.

-- 
Regards,

Laurent Pinchart