linux-kernel - Re: [PATCH v6 07/18] of: dynamic: change type of of_{at,de}tach

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Date:   Thu, 08 Nov 2018 10:48:33 +1100
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Frank Rowand <frowand.list@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Pantelis Antoniou <pantelis.antoniou@...sulko.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Alan Tull <atull@...nel.org>, Moritz Fischer <mdf@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        devicetree@...r.kernel.org, linux-fpga@...r.kernel.org,
        nfont@...ux.vnet.ibm.com,
        Tyrel Datwyler <tyreld@...ux.vnet.ibm.com>
Subject: Re: [PATCH v6 07/18] of: dynamic: change type of of_{at,de}tach_node() to void

Frank Rowand <frowand.list@...il.com> writes:
> On 11/7/18 4:08 AM, Michael Ellerman wrote:
>> frowand.list@...il.com writes:
>> 
>>> From: Frank Rowand <frank.rowand@...y.com>
>>>
>>> of_attach_node() and of_detach_node() always return zero, so
>>> their return value is meaningless.
>> 
>> But should they always return zero?
>> 
>> At least __of_attach_node_sysfs() can fail in several ways.
>
> Sigh.  And of_reconfig_notify() can fail.  And at one point in the
> history the return value of of_reconfig_notify() was returned by
> of_attach_node() if of_reconfig_notify() failed.
>
>> And there's also this in __of_detach_node() which should probably be
>> returning an error:
>> 
>> 	if (WARN_ON(of_node_check_flag(np, OF_DETACHED)))
>>         	return;
>> 
>> 
>> Seems to me we should instead be fixing these to propagate errors,
>> rather than hiding them?
>
> The history of how of_attach_node() stopped propagating errors is
> a bit more complex than I want to dig into at the moment.  So I'll
> drop this patch from the series and add investigating this onto
> my todo list.  I suspect that the result of investigating will be
> that error return values should not be ignored in of_attach_node()
> and of_detach_node(), but should instead be propagated to the
> callers, as you suggest.

Thanks.

cheers