[PATCH] swsusp: reduce code duplication

The changes made by this patch are necessary for the pagedir relocation
simplification in the next patch.   Additionally, these changes allow us to
drop check_pagedir() and make get_safe_page() be a one-line wrapper around
alloc_image_page() (get_safe_page() goes to snapshot.c, because
alloc_image_page() is static and it does not make sense to export it).

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

kernel/power/power.h

@@ -66,7 +66,8 @@ extern asmlinkage int swsusp_arch_suspend(void);
 extern asmlinkage int swsusp_arch_resume(void);
 
 extern int restore_highmem(void);
-extern struct pbe * alloc_pagedir(unsigned nr_pages);
+extern struct pbe *alloc_pagedir(unsigned nr_pages, gfp_t gfp_mask, int safe_needed);
 extern void create_pbe_list(struct pbe *pblist, unsigned nr_pages);
 extern void swsusp_free(void);
+extern int alloc_data_pages(struct pbe *pblist, gfp_t gfp_mask, int safe_needed);
 extern int enough_swap(unsigned nr_pages);

kernel/power/snapshot.c

@@ -269,9 +269,30 @@ void create_pbe_list(struct pbe *pblist, unsigned int nr_pages)
 	pr_debug("create_pbe_list(): initialized %d PBEs\n", num);
 }
 
-static void *alloc_image_page(void)
+/**
+ *	@safe_needed - on resume, for storing the PBE list and the image,
+ *	we can only use memory pages that do not conflict with the pages
+ *	which had been used before suspend.
+ *
+ *	The unsafe pages are marked with the PG_nosave_free flag
+ *
+ *	Allocated but unusable (ie eaten) memory pages should be marked
+ *	so that swsusp_free() can release them
+ */
+
+static inline void *alloc_image_page(gfp_t gfp_mask, int safe_needed)
 {
-	void *res = (void *)get_zeroed_page(GFP_ATOMIC | __GFP_COLD);
+	void *res;
+
+	if (safe_needed)
+		do {
+			res = (void *)get_zeroed_page(gfp_mask);
+			if (res && PageNosaveFree(virt_to_page(res)))
+				/* This is for swsusp_free() */
+				SetPageNosave(virt_to_page(res));
+		} while (res && PageNosaveFree(virt_to_page(res)));
+	else
+		res = (void *)get_zeroed_page(gfp_mask);
 	if (res) {
 		SetPageNosave(virt_to_page(res));
 		SetPageNosaveFree(virt_to_page(res));
@@ -279,6 +300,11 @@ static void *alloc_image_page(void)
 	return res;
 }
 
+unsigned long get_safe_page(gfp_t gfp_mask)
+{
+	return (unsigned long)alloc_image_page(gfp_mask, 1);
+}
+
 /**
  *	alloc_pagedir - Allocate the page directory.
  *
@@ -292,7 +318,7 @@ static void *alloc_image_page(void)
  *	On each page we set up a list of struct_pbe elements.
  */
 
-struct pbe *alloc_pagedir(unsigned int nr_pages)
+struct pbe *alloc_pagedir(unsigned int nr_pages, gfp_t gfp_mask, int safe_needed)
 {
 	unsigned int num;
 	struct pbe *pblist, *pbe;
@@ -301,12 +327,12 @@ struct pbe *alloc_pagedir(unsigned int nr_pages)
 		return NULL;
 
 	pr_debug("alloc_pagedir(): nr_pages = %d\n", nr_pages);
-	pblist = alloc_image_page();
+	pblist = alloc_image_page(gfp_mask, safe_needed);
 	/* FIXME: rewrite this ugly loop */
 	for (pbe = pblist, num = PBES_PER_PAGE; pbe && num < nr_pages;
         		pbe = pbe->next, num += PBES_PER_PAGE) {
 		pbe += PB_PAGE_SKIP;
-		pbe->next = alloc_image_page();
+		pbe->next = alloc_image_page(gfp_mask, safe_needed);
 	}
 	if (!pbe) { /* get_zeroed_page() failed */
 		free_pagedir(pblist);
@@ -354,24 +380,32 @@ static int enough_free_mem(unsigned int nr_pages)
 		(nr_pages + PBES_PER_PAGE - 1) / PBES_PER_PAGE);
 }
 
+int alloc_data_pages(struct pbe *pblist, gfp_t gfp_mask, int safe_needed)
+{
+	struct pbe *p;
+
+	for_each_pbe (p, pblist) {
+		p->address = (unsigned long)alloc_image_page(gfp_mask, safe_needed);
+		if (!p->address)
+			return -ENOMEM;
+	}
+	return 0;
+}
 
 static struct pbe *swsusp_alloc(unsigned int nr_pages)
 {
-	struct pbe *pblist, *p;
+	struct pbe *pblist;
 
-	if (!(pblist = alloc_pagedir(nr_pages))) {
+	if (!(pblist = alloc_pagedir(nr_pages, GFP_ATOMIC | __GFP_COLD, 0))) {
 		printk(KERN_ERR "suspend: Allocating pagedir failed.\n");
 		return NULL;
 	}
 	create_pbe_list(pblist, nr_pages);
 
-	for_each_pbe (p, pblist) {
+	if (alloc_data_pages(pblist, GFP_ATOMIC | __GFP_COLD, 0)) {
-		p->address = (unsigned long)alloc_image_page();
+		printk(KERN_ERR "suspend: Allocating image pages failed.\n");
-		if (!p->address) {
+		swsusp_free();
-			printk(KERN_ERR "suspend: Allocating image pages failed.\n");
+		return NULL;
-			swsusp_free();
-			return NULL;
-		}
 	}
 
 	return pblist;

kernel/power/swsusp.c

@@ -628,59 +628,6 @@ int swsusp_resume(void)
 	return error;
 }
 
-/**
- *	On resume, for storing the PBE list and the image,
- *	we can only use memory pages that do not conflict with the pages
- *	which had been used before suspend.
- *
- *	We don't know which pages are usable until we allocate them.
- *
- *	Allocated but unusable (ie eaten) memory pages are marked so that
- *	swsusp_free() can release them
- */
-
-unsigned long get_safe_page(gfp_t gfp_mask)
-{
-	unsigned long m;
-
-	do {
-		m = get_zeroed_page(gfp_mask);
-		if (m && PageNosaveFree(virt_to_page(m)))
-			/* This is for swsusp_free() */
-			SetPageNosave(virt_to_page(m));
-	} while (m && PageNosaveFree(virt_to_page(m)));
-	if (m) {
-		/* This is for swsusp_free() */
-		SetPageNosave(virt_to_page(m));
-		SetPageNosaveFree(virt_to_page(m));
-	}
-	return m;
-}
-
-/**
- *	check_pagedir - We ensure here that pages that the PBEs point to
- *	won't collide with pages where we're going to restore from the loaded
- *	pages later
- */
-
-static int check_pagedir(struct pbe *pblist)
-{
-	struct pbe *p;
-
-	/* This is necessary, so that we can free allocated pages
-	 * in case of failure
-	 */
-	for_each_pbe (p, pblist)
-		p->address = 0UL;
-
-	for_each_pbe (p, pblist) {
-		p->address = get_safe_page(GFP_ATOMIC);
-		if (!p->address)
-			return -ENOMEM;
-	}
-	return 0;
-}
-
 /**
  *	swsusp_pagedir_relocate - It is possible, that some memory pages
  *	occupied by the list of PBEs collide with pages where we're going to
@@ -990,7 +937,7 @@ static int read_suspend_image(void)
 	int error = 0;
 	struct pbe *p;
 
-	if (!(p = alloc_pagedir(nr_copy_pages)))
+	if (!(p = alloc_pagedir(nr_copy_pages, GFP_ATOMIC, 0)))
 		return -ENOMEM;
 
 	if ((error = read_pagedir(p)))
@@ -1003,7 +950,7 @@ static int read_suspend_image(void)
 
 	/* Allocate memory for the image and read the data from swap */
 
-	error = check_pagedir(pagedir_nosave);
+	error = alloc_data_pages(pagedir_nosave, GFP_ATOMIC, 1);
 
 	if (!error)
 		error = data_read(pagedir_nosave);