Re: [PATCH v2 05/11] xen/arm: Mark device as PCI while creating one

From: Oleksandr Andrushchenko <Oleksandr_Andrushchenko@epam.com>
To: Jan Beulich <jbeulich@suse.com>
Cc: "julien@xen.org" <julien@xen.org>,
	"sstabellini@kernel.org" <sstabellini@kernel.org>,
	Oleksandr Tyshchenko <Oleksandr_Tyshchenko@epam.com>,
	Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>,
	Artem Mygaiev <Artem_Mygaiev@epam.com>,
	"roger.pau@citrix.com" <roger.pau@citrix.com>,
	Bertrand Marquis <bertrand.marquis@arm.com>,
	Rahul Singh <rahul.singh@arm.com>,
	Oleksandr Andrushchenko <Oleksandr_Andrushchenko@epam.com>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Subject: Re: [PATCH v2 05/11] xen/arm: Mark device as PCI while creating one
Date: Tue, 28 Sep 2021 08:09:15 +0000	[thread overview]
Message-ID: <2e8f4316-002f-17d8-b9ec-9886c6bc28fa@epam.com> (raw)
In-Reply-To: <6eefff6f-97ed-e7f5-37f2-96065bd1f27e@suse.com>

On 27.09.21 13:26, Jan Beulich wrote:
> On 27.09.2021 12:04, Oleksandr Andrushchenko wrote:
>> On 27.09.21 13:00, Jan Beulich wrote:
>>> On 27.09.2021 11:35, Oleksandr Andrushchenko wrote:
>>>> On 27.09.21 12:19, Jan Beulich wrote:
>>>>> On 27.09.2021 10:45, Oleksandr Andrushchenko wrote:
>>>>>> On 27.09.21 10:45, Jan Beulich wrote:
>>>>>>> On 23.09.2021 14:54, Oleksandr Andrushchenko wrote:
>>>>>>>> --- a/xen/drivers/passthrough/pci.c
>>>>>>>> +++ b/xen/drivers/passthrough/pci.c
>>>>>>>> @@ -328,6 +328,9 @@ static struct pci_dev *alloc_pdev(struct pci_seg *pseg, u8 bus, u8 devfn)
>>>>>>>>          *((u8*) &pdev->bus) = bus;
>>>>>>>>          *((u8*) &pdev->devfn) = devfn;
>>>>>>>>          pdev->domain = NULL;
>>>>>>>> +#ifdef CONFIG_ARM
>>>>>>>> +    pci_to_dev(pdev)->type = DEV_PCI;
>>>>>>>> +#endif
>>>>>>> I have to admit that I'm not happy about new CONFIG_<arch> conditionals
>>>>>>> here. I'd prefer to see this done by a new arch helper, unless there are
>>>>>>> obstacles I'm overlooking.
>>>>>> Do you mean something like arch_pci_alloc_pdev(dev)?
>>>>> I'd recommend against "alloc" in its name; "new" instead maybe?
>>>> I am fine with arch_pci_new_pdev, but arch prefix points to the fact that
>>>> this is just an architecture specific part of the pdev allocation rather than
>>>> actual pdev allocation itself, so with this respect arch_pci_alloc_pdev seems
>>>> more natural to me.
>>> The bulk of the function is about populating the just allocated struct.
>>> There's no arch-specific part of the allocation (so far, leaving aside
>>> MSI-X), you only want and arch-specific part of the initialization. I
>>> would agree with "alloc" in the name if further allocation was to
>>> happen there.
>> Hm, then arch_pci_init_pdev sounds more reasonable
> Fine with me.

Do we want this to be void or returning an error code? If error code is needed,

then we would also need a roll-back function, e.g. arch_pci_free_pdev or

arch_pci_release_pdev or arch_pci_fini_pdev or something, so it can be used in

case of error or in free_pdev function.

If so, then what's your preference on the name of that function?

>
> Jan
>
>
Thank you,

Oleksandr