[PATCH][Fix] swsusp: do not use memcpy for snapshotting memory

[PATCH][Fix] swsusp: do not use memcpy for snapshotting memory

[Rafael J. Wysocki]

swsusp should not use memcpy for snapshotting memory, because on some
architectures memcpy may increase preempt_count.  Then, as a result, wrong
value of preempt_count is stored in the image.

Replace memcpy in copy_data_pages with an open-coded loop.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
---
 kernel/power/snapshot.c |   10 ++++++++--
 1 files changed, 8 insertions(+), 2 deletions(-)

Index: linux-2.6.17-mm6/kernel/power/snapshot.c
===================================================================
--- linux-2.6.17-mm6.orig/kernel/power/snapshot.c
+++ linux-2.6.17-mm6/kernel/power/snapshot.c
@@ -227,11 +227,17 @@ static void copy_data_pages(struct pbe *
 		for (zone_pfn = 0; zone_pfn < zone->spanned_pages; ++zone_pfn) {
 			if (saveable(zone, &zone_pfn)) {
 				struct page *page;
+				long *src, *dst;
+				int n;
+
 				page = pfn_to_page(zone_pfn + zone->zone_start_pfn);
 				BUG_ON(!pbe);
 				pbe->orig_address = (unsigned long)page_address(page);
-				/* copy_page is not usable for copying task structs. */
-				memcpy((void *)pbe->address, (void *)pbe->orig_address, PAGE_SIZE);
+				/* copy_page and memcpy are not usable for copying task structs. */
+				dst = (long *)pbe->address;
+				src = (long *)pbe->orig_address;
+				for (n = PAGE_SIZE / sizeof(long); n; n--)
+					*dst++ = *src++;
 				pbe = pbe->next;
 			}
 		}