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    Subject[PATCH 4/4] swsusp: reduce the use of global variables
    Date
    The following patch reduces the use of global variables in the
    snapshot-handling part of swsusp, snapshot.c.

    Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

    Index: linux-2.6.14-rc4-mm1/kernel/power/snapshot.c
    ===================================================================
    --- linux-2.6.14-rc4-mm1.orig/kernel/power/snapshot.c 2005-10-17 23:28:40.000000000 +0200
    +++ linux-2.6.14-rc4-mm1/kernel/power/snapshot.c 2005-10-18 00:13:02.000000000 +0200
    @@ -164,37 +164,38 @@
    return 1;
    }

    -static void count_data_pages(void)
    +static unsigned count_data_pages(void)
    {
    struct zone *zone;
    unsigned long zone_pfn;
    + unsigned n;

    - nr_copy_pages = 0;
    -
    + n = 0;
    for_each_zone (zone) {
    if (is_highmem(zone))
    continue;
    mark_free_pages(zone);
    for (zone_pfn = 0; zone_pfn < zone->spanned_pages; ++zone_pfn)
    - nr_copy_pages += saveable(zone, &zone_pfn);
    + n += saveable(zone, &zone_pfn);
    }
    + return n;
    }

    -static void copy_data_pages(void)
    +static void copy_data_pages(struct pbe *pblist)
    {
    struct zone *zone;
    unsigned long zone_pfn;
    - struct pbe *pbe = pagedir_nosave, *p;
    + struct pbe *pbe, *p;

    - pr_debug("copy_data_pages(): pages to copy: %d\n", nr_copy_pages);
    + pbe = pblist;
    for_each_zone (zone) {
    if (is_highmem(zone))
    continue;
    mark_free_pages(zone);
    /* This is necessary for swsusp_free() */
    - for_each_pb_page (p, pagedir_nosave)
    + for_each_pb_page (p, pblist)
    SetPageNosaveFree(virt_to_page(p));
    - for_each_pbe (p, pagedir_nosave)
    + for_each_pbe (p, pblist)
    SetPageNosaveFree(virt_to_page(p->address));
    for (zone_pfn = 0; zone_pfn < zone->spanned_pages; ++zone_pfn) {
    if (saveable(zone, &zone_pfn)) {
    @@ -347,46 +348,39 @@
    * free pages.
    */

    -static int enough_free_mem(void)
    +static int enough_free_mem(unsigned nr_pages)
    {
    pr_debug("swsusp: available memory: %u pages\n", nr_free_pages());
    - return nr_free_pages() > (nr_copy_pages + PAGES_FOR_IO +
    - nr_copy_pages/PBES_PER_PAGE + !!(nr_copy_pages%PBES_PER_PAGE));
    + return nr_free_pages() > (nr_pages + PAGES_FOR_IO +
    + (nr_pages + PBES_PER_PAGE - 1) / PBES_PER_PAGE);
    }


    -static int swsusp_alloc(void)
    +static struct pbe *swsusp_alloc(unsigned nr_pages)
    {
    - struct pbe *p;
    + struct pbe *pblist, *p;

    - pagedir_nosave = NULL;
    -
    - if (MAX_PBES < nr_copy_pages / PBES_PER_PAGE +
    - !!(nr_copy_pages % PBES_PER_PAGE))
    - return -ENOSPC;
    -
    - if (!(pagedir_save = alloc_pagedir(nr_copy_pages))) {
    + if (!(pblist = alloc_pagedir(nr_pages))) {
    printk(KERN_ERR "suspend: Allocating pagedir failed.\n");
    - return -ENOMEM;
    + return NULL;
    }
    - create_pbe_list(pagedir_save, nr_copy_pages);
    - pagedir_nosave = pagedir_save;
    + create_pbe_list(pblist, nr_pages);

    - for_each_pbe (p, pagedir_save) {
    + 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 -ENOMEM;
    + return NULL;
    }
    }

    - return 0;
    + return pblist;
    }

    int swsusp_save(void)
    {
    - int error;
    + unsigned nr_pages;

    pr_debug("swsusp: critical section: \n");
    if (save_highmem()) {
    @@ -396,33 +390,37 @@
    }

    drain_local_pages();
    - count_data_pages();
    - printk("swsusp: Need to copy %u pages\n", nr_copy_pages);
    + nr_pages = count_data_pages();
    + printk("swsusp: Need to copy %u pages\n", nr_pages);

    pr_debug("swsusp: pages needed: %u + %lu + %u, free: %u\n",
    - nr_copy_pages,
    - nr_copy_pages/PBES_PER_PAGE + !!(nr_copy_pages%PBES_PER_PAGE),
    + nr_pages,
    + (nr_pages + PBES_PER_PAGE - 1) / PBES_PER_PAGE,
    PAGES_FOR_IO, nr_free_pages());

    - if (!enough_free_mem()) {
    + /* This is needed because of the fixed size of swsusp_info */
    + if (MAX_PBES < (nr_pages + PBES_PER_PAGE - 1) / PBES_PER_PAGE)
    + return -ENOSPC;
    +
    + if (!enough_free_mem(nr_pages)) {
    printk(KERN_ERR "swsusp: Not enough free memory\n");
    return -ENOMEM;
    }

    - if (!enough_swap()) {
    + if (!enough_swap(nr_pages)) {
    printk(KERN_ERR "swsusp: Not enough free swap\n");
    return -ENOSPC;
    }

    - error = swsusp_alloc();
    - if (error)
    - return error;
    + pagedir_nosave = swsusp_alloc(nr_pages);
    + if (!pagedir_nosave)
    + return -ENOMEM;

    /* During allocating of suspend pagedir, new cold pages may appear.
    * Kill them.
    */
    drain_local_pages();
    - copy_data_pages();
    + copy_data_pages(pagedir_nosave);

    /*
    * End of critical section. From now on, we can write to memory,
    @@ -430,6 +428,8 @@
    * touch swap space! Except we must write out our image of course.
    */

    - printk("swsusp: critical section/: done (%d pages copied)\n", nr_copy_pages );
    + nr_copy_pages = nr_pages;
    +
    + printk("swsusp: critical section/: done (%d pages copied)\n", nr_pages);
    return 0;
    }
    Index: linux-2.6.14-rc4-mm1/kernel/power/swsusp.c
    ===================================================================
    --- linux-2.6.14-rc4-mm1.orig/kernel/power/swsusp.c 2005-10-17 23:28:52.000000000 +0200
    +++ linux-2.6.14-rc4-mm1/kernel/power/swsusp.c 2005-10-18 00:13:02.000000000 +0200
    @@ -543,14 +543,14 @@
    * We should only consider resume_device.
    */

    -int enough_swap(void)
    +int enough_swap(unsigned nr_pages)
    {
    struct sysinfo i;

    si_swapinfo(&i);
    pr_debug("swsusp: available swap: %lu pages\n", i.freeswap);
    - return i.freeswap > (nr_copy_pages + PAGES_FOR_IO +
    - nr_copy_pages/PBES_PER_PAGE + !!(nr_copy_pages%PBES_PER_PAGE));
    + return i.freeswap > (nr_pages + PAGES_FOR_IO +
    + (nr_pages + PBES_PER_PAGE - 1) / PBES_PER_PAGE);
    }


    Index: linux-2.6.14-rc4-mm1/kernel/power/power.h
    ===================================================================
    --- linux-2.6.14-rc4-mm1.orig/kernel/power/power.h 2005-10-17 23:28:29.000000000 +0200
    +++ linux-2.6.14-rc4-mm1/kernel/power/power.h 2005-10-18 00:13:02.000000000 +0200
    @@ -69,4 +69,4 @@
    extern struct pbe * alloc_pagedir(unsigned nr_pages);
    extern void create_pbe_list(struct pbe *pblist, unsigned nr_pages);
    extern void swsusp_free(void);
    -extern int enough_swap(void);
    +extern int enough_swap(unsigned nr_pages);
    -
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