linux-kernel - Re: [PATCH] driver core: Make dev_err

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Date: Fri, 12 Apr 2024 20:07:29 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Raag Jadav <raag.jadav@...el.com>, linux-kernel@...r.kernel.org,
	kernel@...gutronix.de, "Rafael J. Wysocki" <rafael@...nel.org>
Subject: Re: [PATCH] driver core: Make dev_err_probe() silent for -ENOMEM

On Fri, Apr 12, 2024 at 07:03:01PM +0200, Uwe Kleine-König wrote:
> On Fri, Apr 12, 2024 at 07:51:48PM +0300, Andy Shevchenko wrote:
> > On Fri, Apr 12, 2024 at 06:44:05PM +0200, Uwe Kleine-König wrote:
> > > For an out-of-memory error there should be no additional output. Adapt
> > > dev_err_probe() to not emit the error message when err is -ENOMEM.
> > > This simplifies handling errors that might among others be -ENOMEM.

> > ...
> > 
> > 	BUILD_BUG_ON(err == -ENOMEM);
> > 
> > Done!
> 
> Well no, that doesn't do the trick. Consider for example device_add().
> That function can return (at least) -EINVAL and -ENOMEM. To properly
> ensure that the error handling is silent with the current
> dev_err_probe(), we'd need to do:
> 
> 	ret = device_add(...);
> 	if (ret) {
> 		if (ret != -ENOMEM)
> 			return dev_err_probe(...);
> 		else
> 			return ret;
> 	}
> 
> With my suggested patch this can be reduced to:
> 
> 	ret = device_add(...);
> 	if (ret)
> 		return dev_err_probe(...);

Fair enough, but these two should be combined.
Mine is for the rejecting a dead code on the phase of the submission.

-- 
With Best Regards,
Andy Shevchenko