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

> 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
>

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