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From: Peter Maydell <peter.maydell@linaro.org>
Date: Mon, 15 Jun 2015 21:41:05 +0100
Message-ID: <CAFEAcA-WVHUvDS8AD4io5vaJRmQ58q661LJMpHx-5OxRXGNbQA@mail.gmail.com>
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Subject: Re: [Qemu-devel] [PATCH 04/11] qerror: Eliminate
	QERR_DEVICE_NOT_FOUND
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To: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Michael Roth <mdroth@linux.vnet.ibm.com>, Markus Armbruster <armbru@redhat.com>, Stefan Hajnoczi <stefanha@redhat.com>, QEMU Developers <qemu-devel@nongnu.org>

On 15 June 2015 at 16:18, Luiz Capitulino <lcapitulino@redhat.com> wrote:
> On Sat, 13 Jun 2015 16:20:51 +0200
> Markus Armbruster <armbru@redhat.com> wrote:
>
>> Error classes other than ERROR_CLASS_GENERIC_ERROR should not be used
>> in new code.  Hiding them in QERR_ macros makes new uses hard to spot.
>> Fortunately, there's just one such macro left.  Eliminate it with this
>> coccinelle semantic patch:
>>
>>     @@
>>     expression EP, E;
>>     @@
>>     -error_set(EP, QERR_DEVICE_NOT_FOUND, E)
>>     +error_set(EP, ERROR_CLASS_DEVICE_NOT_FOUND, "Device '%s' not found", E)
>
> This is a bit minor, but I think I'd have created a new function instead,
> say error_set_enodev(). This avoids all the duplication. But I'm not asking
> you to change, as the patch is good and this can be done in the future if
> we so want.

The thing about that kind of generic set-an-error function is that
it encourages people to use it rather than providing an error message
that's more specific and helpful for the particular situation. That
might not be a problem in this patch (I haven't read it), but I mention
it because I have a patch onlist elsewhere which undoes a bit of
"generic error based on an errno" in favour of being more specific
about why something didn't work.

thanks
-- PMM