[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>

3 files changed, 52 insertions, 70 deletions

diff --git a/kernel/power/power.h b/kernel/power/power.h
index d4fd96a135ab..c98923e13e75 100644
--- a/kernel/power/power.h
+++ b/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);
diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index 723f5179883e..96cc3e21e97d 100644
--- a/kernel/power/snapshot.c
+++ b/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) {
-                p->address = (unsigned long)alloc_image_page();
-                if (!p->address) {
-                        printk(KERN_ERR "suspend: Allocating image pages failed.\n");
-                        swsusp_free();
-                        return NULL;
-                }
+        if (alloc_data_pages(pblist, GFP_ATOMIC | __GFP_COLD, 0)) {
+                printk(KERN_ERR "suspend: Allocating image pages failed.\n");
+                swsusp_free();
+                return NULL;
         }
 
         return pblist;
diff --git a/kernel/power/swsusp.c b/kernel/power/swsusp.c
index e1ab28b9b217..a456ffe7a3c8 100644
--- a/kernel/power/swsusp.c
+++ b/kernel/power/swsusp.c
@@ -629,59 +629,6 @@ int swsusp_resume(void)
 }
 
 /**
- *      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
  *      restore from the loaded pages later.  We relocate them here.
@@ -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);