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

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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@xxxxxxxx>

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@xxxxxxxx>
---
  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





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