linux-kernel - Re: [PATCH 1/5] ocxl: Rename struct link to ocxl

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Message-Id: <97ad5218-4876-956e-e6ef-fb3449eca68e@au1.ibm.com>
Date:   Wed, 27 Feb 2019 19:18:08 +1100
From:   Andrew Donnellan <andrew.donnellan@....ibm.com>
To:     "Alastair D'Silva" <alastair@...ilva.org>,
        "'Alastair D'Silva'" <alastair@....ibm.com>
Cc:     "'Greg Kurz'" <groug@...d.org>,
        "'Frederic Barrat'" <fbarrat@...ux.ibm.com>,
        "'Arnd Bergmann'" <arnd@...db.de>,
        "'Greg Kroah-Hartman'" <gregkh@...uxfoundation.org>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/5] ocxl: Rename struct link to ocxl_link

On 27/2/19 7:04 pm, Alastair D'Silva wrote:
>> -----Original Message-----
>> From: Andrew Donnellan <andrew.donnellan@....ibm.com>
>> Sent: Wednesday, 27 February 2019 6:55 PM
>> To: Alastair D'Silva <alastair@...ilva.org>; 'Alastair D'Silva'
>> <alastair@....ibm.com>
>> Cc: 'Greg Kurz' <groug@...d.org>; 'Frederic Barrat'
>> <fbarrat@...ux.ibm.com>; 'Arnd Bergmann' <arnd@...db.de>; 'Greg Kroah-
>> Hartman' <gregkh@...uxfoundation.org>; linuxppc-dev@...ts.ozlabs.org;
>> linux-kernel@...r.kernel.org
>> Subject: Re: [PATCH 1/5] ocxl: Rename struct link to ocxl_link
>>
>> On 27/2/19 6:34 pm, Alastair D'Silva wrote:>>> diff --git
>> a/drivers/misc/ocxl/file.c b/drivers/misc/ocxl/file.c index
>>>>> e6a607488f8a..16eb8a60d5c7 100644
>>>>> --- a/drivers/misc/ocxl/file.c
>>>>> +++ b/drivers/misc/ocxl/file.c
>>>>> @@ -152,7 +152,7 @@ static long afu_ioctl_enable_p9_wait(struct
>>>>> ocxl_context *ctx,
>>>>>
>>>>>     		if (status == ATTACHED) {
>>>>>     			int rc;
>>>>> -			struct link *link = ctx->afu->fn->link;
>>>>> +			void *link = ctx->afu->fn->link;
>>>>
>>>> This doesn't look like a rename...
>>>
>>> That corrects the type to what the member (and prototype for
>> ocxl_link_update_pe) declare it as.
>>>
>>> The struct link there is bogus, it shouldn't even compile (since the intended
>> struct link is defined in a different compilation unit), but instead picks up a
>> different definition of 'struct link' from elsewhere.
>>>
>>
>> Given there's only a handful of struct links defined across the entire kernel,
>> I'm going to guess that the definition it's picking up is in fact the ocxl one.
>>
> 
> Unlikely, since that's never in a header. It wasn't caught since it was assigned to/from a void*.

Ah, yeah that'd explain it... and it's a pointer so it never needs to 
know its size. I'm clearly not very good at C.

> 
>> I think the better solution here is to move struct ocxl_link into
>> ocxl_internal.h, change ocxl_fn::link to be struct ocxl_link * rather than void
>> *, and update the function signature for ocxl_link_update_pe() as well.
>   
> Not move it, but we could have an opaque declaration there.
> 

Putting it there would fit with all the other ocxl_* structs, but either 
way, we definitely need a declaration in there and get rid of the void*, t

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@....ibm.com  IBM Australia Limited