linux-kernel - Re: [PATCH 1/8] xen/grant-table: Make set/clear page private code shared

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Message-ID: <089b3c85-cdc4-f8bd-0895-50b2b4aa4ca2@gmail.com>
Date:   Wed, 30 May 2018 08:27:02 +0300
From:   Oleksandr Andrushchenko <andr2000@...il.com>
To:     Juergen Gross <jgross@...e.com>, xen-devel@...ts.xenproject.org,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-media@...r.kernel.org, boris.ostrovsky@...cle.com,
        konrad.wilk@...cle.com
Cc:     daniel.vetter@...el.com, dongwon.kim@...el.com,
        matthew.d.roper@...el.com,
        Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
Subject: Re: [PATCH 1/8] xen/grant-table: Make set/clear page private code
 shared

On 05/30/2018 07:24 AM, Juergen Gross wrote:
> On 25/05/18 17:33, Oleksandr Andrushchenko wrote:
>> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
>>
>> Make set/clear page private code shared and accessible to
>> other kernel modules which can re-use these instead of open-coding.
>>
>> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
>> ---
>>   drivers/xen/grant-table.c | 54 +++++++++++++++++++++++++--------------
>>   include/xen/grant_table.h |  3 +++
>>   2 files changed, 38 insertions(+), 19 deletions(-)
>>
>> diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
>> index 27be107d6480..d7488226e1f2 100644
>> --- a/drivers/xen/grant-table.c
>> +++ b/drivers/xen/grant-table.c
>> @@ -769,29 +769,18 @@ void gnttab_free_auto_xlat_frames(void)
>>   }
>>   EXPORT_SYMBOL_GPL(gnttab_free_auto_xlat_frames);
>>   
>> -/**
>> - * gnttab_alloc_pages - alloc pages suitable for grant mapping into
>> - * @nr_pages: number of pages to alloc
>> - * @pages: returns the pages
>> - */
>> -int gnttab_alloc_pages(int nr_pages, struct page **pages)
>> +int gnttab_pages_set_private(int nr_pages, struct page **pages)
>>   {
>>   	int i;
>> -	int ret;
>> -
>> -	ret = alloc_xenballooned_pages(nr_pages, pages);
>> -	if (ret < 0)
>> -		return ret;
>>   
>>   	for (i = 0; i < nr_pages; i++) {
>>   #if BITS_PER_LONG < 64
>>   		struct xen_page_foreign *foreign;
>>   
>>   		foreign = kzalloc(sizeof(*foreign), GFP_KERNEL);
>> -		if (!foreign) {
>> -			gnttab_free_pages(nr_pages, pages);
>> +		if (!foreign)
>>   			return -ENOMEM;
>> -		}
>> +
>>   		set_page_private(pages[i], (unsigned long)foreign);
>>   #endif
>>   		SetPagePrivate(pages[i]);
>> @@ -799,14 +788,30 @@ int gnttab_alloc_pages(int nr_pages, struct page **pages)
>>   
>>   	return 0;
>>   }
>> -EXPORT_SYMBOL(gnttab_alloc_pages);
>> +EXPORT_SYMBOL(gnttab_pages_set_private);
> EXPORT_SYMBOL_GPL()
Sure, I was confused by the fact that there are only 2 functions in the file
which are exported as:
  - EXPORT_SYMBOL(gnttab_alloc_pages);
  - EXPORT_SYMBOL(gnttab_free_pages);
and those were the base for the new 
gnttab_pages_set_private/gnttab_pages_clear_private
This made me think I have to retain the same EXPORT_SYMBOL for them.
Do you want me to add one more patch into this series and change
gnttab_alloc_pages/gnttab_free_pages to GPL as well?
>>   
>>   /**
>> - * gnttab_free_pages - free pages allocated by gnttab_alloc_pages()
>> - * @nr_pages; number of pages to free
>> - * @pages: the pages
>> + * gnttab_alloc_pages - alloc pages suitable for grant mapping into
>> + * @nr_pages: number of pages to alloc
>> + * @pages: returns the pages
>>    */
>> -void gnttab_free_pages(int nr_pages, struct page **pages)
>> +int gnttab_alloc_pages(int nr_pages, struct page **pages)
>> +{
>> +	int ret;
>> +
>> +	ret = alloc_xenballooned_pages(nr_pages, pages);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	ret = gnttab_pages_set_private(nr_pages, pages);
>> +	if (ret < 0)
>> +		gnttab_free_pages(nr_pages, pages);
>> +
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL(gnttab_alloc_pages);
>> +
>> +void gnttab_pages_clear_private(int nr_pages, struct page **pages)
>>   {
>>   	int i;
>>   
>> @@ -818,6 +823,17 @@ void gnttab_free_pages(int nr_pages, struct page **pages)
>>   			ClearPagePrivate(pages[i]);
>>   		}
>>   	}
>> +}
>> +EXPORT_SYMBOL(gnttab_pages_clear_private);
> EXPORT_SYMBOL_GPL()
Will change
>
> Juergen
Thank you,
Oleksandr