linux-kernel - Re: [PATCH] PM / OPP: -ENOSYS is applicable only to syscalls

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Date:	Wed, 27 Apr 2016 08:17:04 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>
Cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	linaro-kernel@...ts.linaro.org, linux-pm@...r.kernel.org,
	arnd.bergmann@...aro.org, andrew@...n.ch,
	gregory.clement@...e-electrons.com, jason@...edaemon.net,
	sebastian.hesselbarth@...il.com,
	thomas.petazzoni@...e-electrons.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PM / OPP: -ENOSYS is applicable only to syscalls

On 22-04-16, 15:59, One Thousand Gnomes wrote:
> On Fri, 22 Apr 2016 14:42:31 +0200
> "Rafael J. Wysocki" <rjw@...ysocki.net> wrote:
> 
> > On Friday, April 22, 2016 08:46:51 AM Viresh Kumar wrote:
> > > Some of the routines have use -ENOSYS, which is supposed to be used only
> > > for syscalls. Replace that with -EINVAL.  
> > 
> > -EINVAL specifically means "invalid argument".
> > 
> > What about using -ENXIO instead?
> 
> That specifically means "device not present", but might be reasonable.
> Quite a bit of the kernel uses EOPNOTSUPP (operation not supported).

That looks reasonable to me.. Will switch to that.

> Before you change it though please check how existing userspace does
> error handling. It's nice to use more "correct" error codes, but that's
> not sufficient reason if it turns out that existing user space checks for
> ENOSYS for example.

Userspace doesn't interact directly with this stuff, its pretty much within the
kernel. So it should be fine.

Thanks Alan.

-- 
viresh