linux-kernel - Re: [PATCH 3/6] PCI: Introduce devm_of_pci_get_host_bridge

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Date:   Wed, 2 May 2018 07:39:42 +0200
From:   Jan Kiszka <jan.kiszka@...mens.com>
To:     Sinan Kaya <okaya@...eaurora.org>,
        Bjorn Helgaas <helgaas@...nel.org>
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 3/6] PCI: Introduce devm_of_pci_get_host_bridge_resources

On 2018-04-30 20:43, Sinan Kaya wrote:
> On 4/30/2018 2:40 PM, Bjorn Helgaas wrote:
>> On Sat, Apr 28, 2018 at 09:28:47AM +0200, Jan Kiszka wrote:
>>> On 2018-04-28 00:24, Bjorn Helgaas wrote:
>>>> On Tue, Apr 24, 2018 at 05:13:39PM +0200, Jan Kiszka wrote:
>>>>> From: Jan Kiszka <jan.kiszka@...mens.com>
>>>>>
>>>>> of_pci_get_host_bridge_resources allocates the resource structures it
>>>>> fills dynamically, but none of its callers care to release them so far.
>>>>> Rather than requiring everyone to do this explicitly, introduce a
>>>>> managed version of that service. This differs API-wise only in taking a
>>>>> reference to the associated device, rather than to the device tree node.
>>>>>
>>>>> As of_pci_get_host_bridge_resources is an exported interface, we cannot
>>>>> simply drop it at this point. After converting all in-tree users to the
>>>>> new API, we could phase out the unmanaged one over some grace period.
>>>>
>>>> It looks like it might be possible to split this into three or four
>>>> patches:
>>>>
>>>>   1) Factor __of_pci_get_host_bridge_resources() out of
>>>>      of_pci_get_host_bridge_resources()
>>>>
>>>>   2) Add struct device * argument
>>>>
>>>>   3) Convert pr_info() to dev_info()
>>>>
>>>>   4) Add devm_of_pci_get_host_bridge_resources()
>>>
>>> Will do. I'm even considering
>>>
>>> 5) mark of_pci_get_host_bridge_resources() __deprecated, due to the leak
>>>    and no remaining in-tree user - what do you think?
>>
>> Sounds good.
>>
>> It'd be nice if we had some guideline about deprecation -- whether we
>> actually need to mark things __deprecated, and then how long to wait
>> before actually removing them, but I don't see anything in
>> Documentation/.
> 
> I'm under the impression that we don't quite care about out-of-tree drivers.
> I have seen many times out-of-tree drivers to be broken due to API changes,
> renames or even parameter meaning change. 
> 
> If the plan is to remove the API, just remove the API today.

I've already sent a __deprecated patch on Monday [1], in v2 of this
series [2]. Please vote against that there, and I will replace it with a
complete removal of that API.

Thanks,
Jan

[1] https://lkml.org/lkml/2018/4/30/22
[2] https://lkml.org/lkml/2018/4/30/24

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