Re: [PATCH 06/17] xen/x86: mm: Fix the comment on top put_page_from_l2e() to use 'mfn'

From: Julien Grall <julien@xen.org>
To: Jan Beulich <jbeulich@suse.com>
Cc: xen-devel@lists.xenproject.org,
	"Julien Grall" <jgrall@amazon.com>,
	"Roger Pau Monné" <roger.pau@citrix.com>, "Wei Liu" <wl@xen.org>,
	"Andrew Cooper" <andrew.cooper3@citrix.com>
Subject: Re: [PATCH 06/17] xen/x86: mm: Fix the comment on top put_page_from_l2e() to use 'mfn'
Date: Sat, 18 Apr 2020 11:54:30 +0100	[thread overview]
Message-ID: <09bf5a4a-e60f-3f98-1a3d-00e4777665fa@xen.org> (raw)
In-Reply-To: <4f6d47dd-997d-977e-690d-7f21be2617a0@suse.com>

Hi Jan,

On 26/03/2020 15:51, Jan Beulich wrote:
> On 22.03.2020 17:14, julien@xen.org wrote:
>> From: Julien Grall <jgrall@amazon.com>
>>
>> We are using the 'mfn' to refer to machine frame. As this function deal
>> with 'mfn', replace 'pfn' with 'mfn'.
>>
>> Signed-off-by: Julien Grall <jgrall@amazon.com>
>>
>> ---
>>
>> I am not entirely sure to understand the comment on top of the
>> function, so this change may be wrong.
> 
> Looking at the history of the function, ...
> 
>> --- a/xen/arch/x86/mm.c
>> +++ b/xen/arch/x86/mm.c
>> @@ -1321,7 +1321,7 @@ static int put_data_pages(struct page_info *page, bool writeable, int pt_shift)
>>   }
>>   
>>   /*
>> - * NB. Virtual address 'l2e' maps to a machine address within frame 'pfn'.
>> + * NB. Virtual address 'l2e' maps to a machine address within frame 'mfn'.
>>    * Note also that this automatically deals correctly with linear p.t.'s.
>>    */
>>   static int put_page_from_l2e(l2_pgentry_t l2e, mfn_t l2mfn, unsigned int flags)
> 
> ... it used to be
> 
> static int put_page_from_l2e(l2_pgentry_t l2e, unsigned long pfn)
> 
> When the rename occurred (in the context of or as a follow-up to an
> XSA iirc), the comment adjustment was apparently missed. With the
> referenced name matching that of the function argument (l2mfn)
> Acked-by: Jan Beulich <jbeulich@suse.com>

I will update the reference to use 'l2mfn' and also add a word that the 
comment was adjusted in ea51977a7aa5e645680a7194550fbceb59004ccf.

Cheers,

-- 
Julien Grall