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

On 05/31/2018 12:34 AM, Dongwon Kim wrote:

On Fri, May 25, 2018 at 06:33:24PM +0300, Oleksandr Andrushchenko wrote:

...

From: Oleksandr Andrushchenko oleksandr_andrushchenko@epam.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@epam.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)
  

Don't we have to free previously allocated "foreign"(s) if it fails in the middle (e.g. 0 < i && i < nr_pages - 1) before returning?

gnttab_free_pages(nr_pages, pages); will take care of it when called from outside, see below. It can also handle partial allocations, so no problem here

...

	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);

/**

• • 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);

+/**

• • gnttab_free_pages - free pages allocated by gnttab_alloc_pages()
• • @nr_pages; number of pages to free
• • @pages: the pages
• */

+void gnttab_free_pages(int nr_pages, struct page **pages) +{

• gnttab_pages_clear_private(nr_pages, pages); free_xenballooned_pages(nr_pages, pages); } EXPORT_SYMBOL(gnttab_free_pages);

diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h index 2e37741f6b8d..de03f2542bb7 100644 --- a/include/xen/grant_table.h +++ b/include/xen/grant_table.h @@ -198,6 +198,9 @@ void gnttab_free_auto_xlat_frames(void); int gnttab_alloc_pages(int nr_pages, struct page **pages); void gnttab_free_pages(int nr_pages, struct page **pages);

+int gnttab_pages_set_private(int nr_pages, struct page **pages); +void gnttab_pages_clear_private(int nr_pages, struct page **pages);

• int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops, struct gnttab_map_grant_ref *kmap_ops, struct page **pages, unsigned int count);

-- 2.17.0