// SPDX-License-Identifier: GPL-2.0-only
/*
 * linux/kernel/power/swap.c
 *
 * This file provides functions for reading the suspend image from
 * and writing it to a swap partition.
 *
 * Copyright (C) 1998,2001-2005 Pavel Machek <pavel@ucw.cz>
 * Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
 * Copyright (C) 2010-2012 Bojan Smojver <bojan@rexursive.com>
 */

#define pr_fmt(fmt) "PM: " fmt

#include <crypto/acompress.h>
#include <linux/module.h>
#include <linux/file.h>
#include <linux/delay.h>
#include <linux/bitops.h>
#include <linux/device.h>
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/swap.h>
#include <linux/swapops.h>
#include <linux/pm.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/cpumask.h>
#include <linux/atomic.h>
#include <linux/kthread.h>
#include <linux/crc32.h>
#include <linux/ktime.h>

#include "power.h"

#define HIBERNATE_SIG   "S1SUSPEND"

u32 swsusp_hardware_signature;

/*
 * When reading an {un,}compressed image, we may restore pages in place,
 * in which case some architectures need these pages cleaning before they
 * can be executed. We don't know which pages these may be, so clean the lot.
 */
static bool clean_pages_on_read;
static bool clean_pages_on_decompress;

/*
 * The swap map is a data structure used for keeping track of each page
 * written to a swap partition.  It consists of many swap_map_page structures
 * that contain each an array of MAP_PAGE_ENTRIES swap entries.  These
 * structures are stored on the swap and linked together with the help of the
 * .next_swap member.
 *
 * The swap map is created during suspend.  The swap map pages are allocated and
 * populated one at a time, so we only need one memory page to set up the entire
 * structure.
 *
 * During resume we pick up all swap_map_page structures into a list.
 */
#define MAP_PAGE_ENTRIES        (PAGE_SIZE / sizeof(sector_t) - 1)

/*
 * Number of free pages that are not high.
 */
static inline unsigned long low_free_pages(void)
{
        return nr_free_pages() - nr_free_highpages();
}

/*
 * Number of pages required to be kept free while writing the image. Always
 * half of all available low pages before the writing starts.
 */
static inline unsigned long reqd_free_pages(void)
{
        return low_free_pages() / 2;
}

struct swap_map_page {
        sector_t entries[MAP_PAGE_ENTRIES];
        sector_t next_swap;
};

struct swap_map_page_list {
        struct swap_map_page *map;
        struct swap_map_page_list *next;
};

/*
 * The swap_map_handle structure is used for handling swap in a file-alike way.
 */
struct swap_map_handle {
        struct swap_map_page *cur;
        struct swap_map_page_list *maps;
        sector_t cur_swap;
        sector_t first_sector;
        unsigned int k;
        unsigned long reqd_free_pages;
        u32 crc32;
};

struct swsusp_header {
        char reserved[PAGE_SIZE - 20 - sizeof(sector_t) - sizeof(int) -
                      sizeof(u32) - sizeof(u32)];
        u32     hw_sig;
        u32     crc32;
        sector_t image;
        unsigned int flags;     /* Flags to pass to the "boot" kernel */
        char    orig_sig[10];
        char    sig[10];
} __packed;

static struct swsusp_header *swsusp_header;

/*
 * The following functions are used for tracing the allocated swap pages, so
 * that they can be freed in case of an error.
 */
struct swsusp_extent {
        struct rb_node node;
        unsigned long start;
        unsigned long end;
};

static struct rb_root swsusp_extents = RB_ROOT;

static int swsusp_extents_insert(unsigned long swap_offset)
{
        struct rb_node **new = &(swsusp_extents.rb_node);
        struct rb_node *parent = NULL;
        struct swsusp_extent *ext;

        /* Figure out where to put the new node */
        while (*new) {
                ext = rb_entry(*new, struct swsusp_extent, node);
                parent = *new;
                if (swap_offset < ext->start) {
                        /* Try to merge */
                        if (swap_offset == ext->start - 1) {
                                ext->start--;
                                return 0;
                        }
                        new = &((*new)->rb_left);
                } else if (swap_offset > ext->end) {
                        /* Try to merge */
                        if (swap_offset == ext->end + 1) {
                                ext->end++;
                                return 0;
                        }
                        new = &((*new)->rb_right);
                } else {
                        /* It already is in the tree */
                        return -EINVAL;
                }
        }
        /* Add the new node and rebalance the tree. */
        ext = kzalloc_obj(struct swsusp_extent);
        if (!ext)
                return -ENOMEM;

        ext->start = swap_offset;
        ext->end = swap_offset;
        rb_link_node(&ext->node, parent, new);
        rb_insert_color(&ext->node, &swsusp_extents);
        return 0;
}

sector_t alloc_swapdev_block(int swap)
{
        unsigned long offset;

        /*
         * Allocate a swap page and register that it has been allocated, so that
         * it can be freed in case of an error.
         */
        offset = swp_offset(swap_alloc_hibernation_slot(swap));
        if (offset) {
                if (swsusp_extents_insert(offset))
                        swap_free_hibernation_slot(swp_entry(swap, offset));
                else
                        return swapdev_block(swap, offset);
        }
        return 0;
}

void free_all_swap_pages(int swap)
{
        unsigned long offset;
        struct rb_node *node;

        /*
         * Free swap pages allocated for saving image data.  It also frees the
         * extents used to register which swap entries had been allocated.
         */
        while ((node = swsusp_extents.rb_node)) {
                struct swsusp_extent *ext;

                ext = rb_entry(node, struct swsusp_extent, node);
                rb_erase(node, &swsusp_extents);

                for (offset = ext->start; offset <= ext->end; offset++)
                        swap_free_hibernation_slot(swp_entry(swap, offset));

                kfree(ext);
        }
}

int swsusp_swap_in_use(void)
{
        return (swsusp_extents.rb_node != NULL);
}

/*
 * General things
 */

static unsigned short root_swap = 0xffff;
static struct file *hib_resume_bdev_file;

struct hib_bio_batch {
        atomic_t                count;
        wait_queue_head_t       wait;
        blk_status_t            error;
        struct blk_plug         plug;
};

static void hib_init_batch(struct hib_bio_batch *hb)
{
        atomic_set(&hb->count, 0);
        init_waitqueue_head(&hb->wait);
        hb->error = BLK_STS_OK;
        blk_start_plug(&hb->plug);
}

static void hib_finish_batch(struct hib_bio_batch *hb)
{
        blk_finish_plug(&hb->plug);
}

static void hib_end_io(struct bio *bio)
{
        struct hib_bio_batch *hb = bio->bi_private;
        struct page *page = bio_first_page_all(bio);

        if (bio->bi_status) {
                pr_alert("Read-error on swap-device (%u:%u:%Lu)\n",
                         MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),
                         (unsigned long long)bio->bi_iter.bi_sector);
        }

        if (bio_data_dir(bio) == WRITE)
                put_page(page);
        else if (clean_pages_on_read)
                flush_icache_range((unsigned long)page_address(page),
                                   (unsigned long)page_address(page) + PAGE_SIZE);

        if (bio->bi_status && !hb->error)
                hb->error = bio->bi_status;
        if (atomic_dec_and_test(&hb->count))
                wake_up(&hb->wait);

        bio_put(bio);
}

static int hib_submit_io_sync(blk_opf_t opf, pgoff_t page_off, void *addr)
{
        return bdev_rw_virt(file_bdev(hib_resume_bdev_file),
                        page_off * (PAGE_SIZE >> 9), addr, PAGE_SIZE, opf);
}

static int hib_submit_io_async(blk_opf_t opf, pgoff_t page_off, void *addr,
                         struct hib_bio_batch *hb)
{
        struct bio *bio;

        bio = bio_alloc(file_bdev(hib_resume_bdev_file), 1, opf,
                        GFP_NOIO | __GFP_HIGH);
        bio->bi_iter.bi_sector = page_off * (PAGE_SIZE >> 9);
        bio_add_virt_nofail(bio, addr, PAGE_SIZE);
        bio->bi_end_io = hib_end_io;
        bio->bi_private = hb;
        atomic_inc(&hb->count);
        submit_bio(bio);
        return 0;
}

static int hib_wait_io(struct hib_bio_batch *hb)
{
        /*
         * We are relying on the behavior of blk_plug that a thread with
         * a plug will flush the plug list before sleeping.
         */
        wait_event(hb->wait, atomic_read(&hb->count) == 0);
        return blk_status_to_errno(hb->error);
}

/*
 * Saving part
 */

static int mark_swapfiles(struct swap_map_handle *handle, unsigned int flags)
{
        int error;

        hib_submit_io_sync(REQ_OP_READ, swsusp_resume_block, swsusp_header);
        if (!memcmp("SWAP-SPACE",swsusp_header->sig, 10) ||
            !memcmp("SWAPSPACE2",swsusp_header->sig, 10)) {
                memcpy(swsusp_header->orig_sig,swsusp_header->sig, 10);
                memcpy(swsusp_header->sig, HIBERNATE_SIG, 10);
                swsusp_header->image = handle->first_sector;
                if (swsusp_hardware_signature) {
                        swsusp_header->hw_sig = swsusp_hardware_signature;
                        flags |= SF_HW_SIG;
                }
                swsusp_header->flags = flags;
                if (flags & SF_CRC32_MODE)
                        swsusp_header->crc32 = handle->crc32;
                error = hib_submit_io_sync(REQ_OP_WRITE | REQ_SYNC,
                                      swsusp_resume_block, swsusp_header);
        } else {
                pr_err("Swap header not found!\n");
                error = -ENODEV;
        }
        return error;
}

/*
 * Hold the swsusp_header flag. This is used in software_resume() in
 * 'kernel/power/hibernate' to check if the image is compressed and query
 * for the compression algorithm support(if so).
 */
unsigned int swsusp_header_flags;

static int swsusp_swap_check(void)
{
        int res;

        /*
         * Check if the resume device is a swap device and get its index (if so).
         * This is called before saving the image.
         */
        if (swsusp_resume_device)
                res = swap_type_of(swsusp_resume_device, swsusp_resume_block);
        else
                res = find_first_swap(&swsusp_resume_device);
        if (res < 0)
                return res;
        root_swap = res;

        hib_resume_bdev_file = bdev_file_open_by_dev(swsusp_resume_device,
                        BLK_OPEN_WRITE, NULL, NULL);
        if (IS_ERR(hib_resume_bdev_file))
                return PTR_ERR(hib_resume_bdev_file);

        return 0;
}

static int write_page(void *buf, sector_t offset, struct hib_bio_batch *hb)
{
        gfp_t gfp = GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY;
        void *src;
        int ret;

        if (!offset)
                return -ENOSPC;

        if (!hb)
                goto sync_io;

        src = (void *)__get_free_page(gfp);
        if (!src) {
                ret = hib_wait_io(hb); /* Free pages */
                if (ret)
                        return ret;
                src = (void *)__get_free_page(gfp);
                if (WARN_ON_ONCE(!src))
                        goto sync_io;
        }

        copy_page(src, buf);
        return hib_submit_io_async(REQ_OP_WRITE | REQ_SYNC, offset, src, hb);
sync_io:
        return hib_submit_io_sync(REQ_OP_WRITE | REQ_SYNC, offset, buf);
}

static void release_swap_writer(struct swap_map_handle *handle)
{
        if (handle->cur)
                free_page((unsigned long)handle->cur);
        handle->cur = NULL;
}

static int get_swap_writer(struct swap_map_handle *handle)
{
        int ret;

        ret = swsusp_swap_check();
        if (ret) {
                if (ret != -ENOSPC)
                        pr_err("Cannot find swap device, try swapon -a\n");
                return ret;
        }
        handle->cur = (struct swap_map_page *)get_zeroed_page(GFP_KERNEL);
        if (!handle->cur) {
                ret = -ENOMEM;
                goto err_close;
        }
        handle->cur_swap = alloc_swapdev_block(root_swap);
        if (!handle->cur_swap) {
                ret = -ENOSPC;
                goto err_rel;
        }
        handle->k = 0;
        handle->reqd_free_pages = reqd_free_pages();
        handle->first_sector = handle->cur_swap;
        return 0;
err_rel:
        release_swap_writer(handle);
err_close:
        swsusp_close();
        return ret;
}

static int swap_write_page(struct swap_map_handle *handle, void *buf,
                struct hib_bio_batch *hb)
{
        int error;
        sector_t offset;

        if (!handle->cur)
                return -EINVAL;
        offset = alloc_swapdev_block(root_swap);
        error = write_page(buf, offset, hb);
        if (error)
                return error;
        handle->cur->entries[handle->k++] = offset;
        if (handle->k >= MAP_PAGE_ENTRIES) {
                offset = alloc_swapdev_block(root_swap);
                if (!offset)
                        return -ENOSPC;
                handle->cur->next_swap = offset;
                error = write_page(handle->cur, handle->cur_swap, hb);
                if (error)
                        goto out;
                clear_page(handle->cur);
                handle->cur_swap = offset;
                handle->k = 0;

                if (hb && low_free_pages() <= handle->reqd_free_pages) {
                        error = hib_wait_io(hb);
                        if (error)
                                goto out;
                        /*
                         * Recalculate the number of required free pages, to
                         * make sure we never take more than half.
                         */
                        handle->reqd_free_pages = reqd_free_pages();
                }
        }
 out:
        return error;
}

static int flush_swap_writer(struct swap_map_handle *handle)
{
        if (handle->cur && handle->cur_swap)
                return write_page(handle->cur, handle->cur_swap, NULL);
        else
                return -EINVAL;
}

static int swap_writer_finish(struct swap_map_handle *handle,
                unsigned int flags, int error)
{
        if (!error) {
                pr_info("S");
                error = mark_swapfiles(handle, flags);
                pr_cont("|\n");
                flush_swap_writer(handle);
        }

        if (error)
                free_all_swap_pages(root_swap);
        release_swap_writer(handle);
        swsusp_close();

        return error;
}

/*
 * Bytes we need for compressed data in worst case. We assume(limitation)
 * this is the worst of all the compression algorithms.
 */
#define bytes_worst_compress(x) ((x) + ((x) / 16) + 64 + 3 + 2)

/* We need to remember how much compressed data we need to read. */
#define CMP_HEADER      sizeof(size_t)

/* Number of pages/bytes we'll compress at one time. */
#define UNC_PAGES       32
#define UNC_SIZE        (UNC_PAGES * PAGE_SIZE)

/* Number of pages we need for compressed data (worst case). */
#define CMP_PAGES       DIV_ROUND_UP(bytes_worst_compress(UNC_SIZE) + \
                                CMP_HEADER, PAGE_SIZE)
#define CMP_SIZE        (CMP_PAGES * PAGE_SIZE)

/* Default number of threads for compression/decompression. */
#define CMP_THREADS    3
static unsigned int hibernate_compression_threads = CMP_THREADS;

/* Minimum/maximum number of pages for read buffering. */
#define CMP_MIN_RD_PAGES        1024
#define CMP_MAX_RD_PAGES        8192

static int save_image(struct swap_map_handle *handle,
                      struct snapshot_handle *snapshot,
                      unsigned int nr_to_write)
{
        unsigned int m;
        int ret;
        int nr_pages;
        int err2;
        struct hib_bio_batch hb;
        ktime_t start;
        ktime_t stop;

        hib_init_batch(&hb);

        pr_info("Saving image data pages (%u pages)...\n",
                nr_to_write);
        m = nr_to_write / 10;
        if (!m)
                m = 1;
        nr_pages = 0;
        start = ktime_get();
        while (1) {
                ret = snapshot_read_next(snapshot);
                if (ret <= 0)
                        break;
                ret = swap_write_page(handle, data_of(*snapshot), &hb);
                if (ret)
                        break;
                if (!(nr_pages % m))
                        pr_info("Image saving progress: %3d%%\n",
                                nr_pages / m * 10);
                nr_pages++;
        }
        err2 = hib_wait_io(&hb);
        hib_finish_batch(&hb);
        stop = ktime_get();
        if (!ret)
                ret = err2;
        if (!ret)
                pr_info("Image saving done\n");
        swsusp_show_speed(start, stop, nr_to_write, "Wrote");
        return ret;
}

/*
 * Structure used for CRC32.
 */
struct crc_data {
        struct task_struct *thr;                  /* thread */
        atomic_t ready;                           /* ready to start flag */
        atomic_t stop;                            /* ready to stop flag */
        unsigned run_threads;                     /* nr current threads */
        wait_queue_head_t go;                     /* start crc update */
        wait_queue_head_t done;                   /* crc update done */
        u32 *crc32;                               /* points to handle's crc32 */
        size_t **unc_len;                         /* uncompressed lengths */
        unsigned char **unc;                      /* uncompressed data */
};

static struct crc_data *alloc_crc_data(int nr_threads)
{
        struct crc_data *crc;

        crc = kzalloc_obj(*crc);
        if (!crc)
                return NULL;

        crc->unc = kcalloc(nr_threads, sizeof(*crc->unc), GFP_KERNEL);
        if (!crc->unc)
                goto err_free_crc;

        crc->unc_len = kzalloc_objs(*crc->unc_len, nr_threads);
        if (!crc->unc_len)
                goto err_free_unc;

        return crc;

err_free_unc:
        kfree(crc->unc);
err_free_crc:
        kfree(crc);
        return NULL;
}

static void free_crc_data(struct crc_data *crc)
{
        if (!crc)
                return;

        if (crc->thr)
                kthread_stop(crc->thr);

        kfree(crc->unc_len);
        kfree(crc->unc);
        kfree(crc);
}

static int crc32_threadfn(void *data)
{
        struct crc_data *d = data;
        unsigned i;

        while (1) {
                wait_event(d->go, atomic_read_acquire(&d->ready) ||
                                  kthread_should_stop());
                if (kthread_should_stop()) {
                        d->thr = NULL;
                        atomic_set_release(&d->stop, 1);
                        wake_up(&d->done);
                        break;
                }
                atomic_set(&d->ready, 0);

                for (i = 0; i < d->run_threads; i++)
                        *d->crc32 = crc32_le(*d->crc32,
                                             d->unc[i], *d->unc_len[i]);
                atomic_set_release(&d->stop, 1);
                wake_up(&d->done);
        }
        return 0;
}

/*
 * Structure used for data compression.
 */
struct cmp_data {
        struct task_struct *thr;                  /* thread */
        struct crypto_acomp *cc;                  /* crypto compressor */
        struct acomp_req *cr;                     /* crypto request */
        atomic_t ready;                           /* ready to start flag */
        atomic_t stop;                            /* ready to stop flag */
        int ret;                                  /* return code */
        wait_queue_head_t go;                     /* start compression */
        wait_queue_head_t done;                   /* compression done */
        size_t unc_len;                           /* uncompressed length */
        size_t cmp_len;                           /* compressed length */
        unsigned char unc[UNC_SIZE];              /* uncompressed buffer */
        unsigned char cmp[CMP_SIZE];              /* compressed buffer */
};

/* Indicates the image size after compression */
static atomic64_t compressed_size = ATOMIC_INIT(0);

static int compress_threadfn(void *data)
{
        struct cmp_data *d = data;

        while (1) {
                wait_event(d->go, atomic_read_acquire(&d->ready) ||
                                  kthread_should_stop());
                if (kthread_should_stop()) {
                        d->thr = NULL;
                        d->ret = -1;
                        atomic_set_release(&d->stop, 1);
                        wake_up(&d->done);
                        break;
                }
                atomic_set(&d->ready, 0);

                acomp_request_set_callback(d->cr, CRYPTO_TFM_REQ_MAY_SLEEP,
                                           NULL, NULL);
                acomp_request_set_src_nondma(d->cr, d->unc, d->unc_len);
                acomp_request_set_dst_nondma(d->cr, d->cmp + CMP_HEADER,
                                             CMP_SIZE - CMP_HEADER);
                d->ret = crypto_acomp_compress(d->cr);
                d->cmp_len = d->cr->dlen;

                atomic64_add(d->cmp_len, &compressed_size);
                atomic_set_release(&d->stop, 1);
                wake_up(&d->done);
        }
        return 0;
}

static int save_compressed_image(struct swap_map_handle *handle,
                                 struct snapshot_handle *snapshot,
                                 unsigned int nr_to_write)
{
        unsigned int m;
        int ret = 0;
        int nr_pages;
        int err2;
        struct hib_bio_batch hb;
        ktime_t start;
        ktime_t stop;
        size_t off;
        unsigned int thr, run_threads, nr_threads;
        unsigned char *page = NULL;
        struct cmp_data *data = NULL;
        struct crc_data *crc = NULL;

        hib_init_batch(&hb);

        atomic64_set(&compressed_size, 0);

        /*
         * We'll limit the number of threads for compression to limit memory
         * footprint.
         */
        nr_threads = num_online_cpus() - 1;
        nr_threads = clamp_val(nr_threads, 1, hibernate_compression_threads);

        page = (void *)__get_free_page(GFP_NOIO | __GFP_HIGH);
        if (!page) {
                pr_err("Failed to allocate %s page\n", hib_comp_algo);
                ret = -ENOMEM;
                goto out_clean;
        }

        data = vcalloc(nr_threads, sizeof(*data));
        if (!data) {
                pr_err("Failed to allocate %s data\n", hib_comp_algo);
                ret = -ENOMEM;
                goto out_clean;
        }

        crc = alloc_crc_data(nr_threads);
        if (!crc) {
                pr_err("Failed to allocate crc\n");
                ret = -ENOMEM;
                goto out_clean;
        }

        /*
         * Start the compression threads.
         */
        for (thr = 0; thr < nr_threads; thr++) {
                init_waitqueue_head(&data[thr].go);
                init_waitqueue_head(&data[thr].done);

                data[thr].cc = crypto_alloc_acomp(hib_comp_algo, 0, CRYPTO_ALG_ASYNC);
                if (IS_ERR_OR_NULL(data[thr].cc)) {
                        pr_err("Could not allocate comp stream %ld\n", PTR_ERR(data[thr].cc));
                        ret = -EFAULT;
                        goto out_clean;
                }

                data[thr].cr = acomp_request_alloc(data[thr].cc);
                if (!data[thr].cr) {
                        pr_err("Could not allocate comp request\n");
                        ret = -ENOMEM;
                        goto out_clean;
                }

                data[thr].thr = kthread_run(compress_threadfn,
                                            &data[thr],
                                            "image_compress/%u", thr);
                if (IS_ERR(data[thr].thr)) {
                        data[thr].thr = NULL;
                        pr_err("Cannot start compression threads\n");
                        ret = -ENOMEM;
                        goto out_clean;
                }
        }

        /*
         * Start the CRC32 thread.
         */
        init_waitqueue_head(&crc->go);
        init_waitqueue_head(&crc->done);

        handle->crc32 = 0;
        crc->crc32 = &handle->crc32;
        for (thr = 0; thr < nr_threads; thr++) {
                crc->unc[thr] = data[thr].unc;
                crc->unc_len[thr] = &data[thr].unc_len;
        }

        crc->thr = kthread_run(crc32_threadfn, crc, "image_crc32");
        if (IS_ERR(crc->thr)) {
                crc->thr = NULL;
                pr_err("Cannot start CRC32 thread\n");
                ret = -ENOMEM;
                goto out_clean;
        }

        /*
         * Adjust the number of required free pages after all allocations have
         * been done. We don't want to run out of pages when writing.
         */
        handle->reqd_free_pages = reqd_free_pages();

        pr_info("Using %u thread(s) for %s compression\n", nr_threads, hib_comp_algo);
        pr_info("Compressing and saving image data (%u pages)...\n",
                nr_to_write);
        m = nr_to_write / 10;
        if (!m)
                m = 1;
        nr_pages = 0;
        start = ktime_get();
        for (;;) {
                for (thr = 0; thr < nr_threads; thr++) {
                        for (off = 0; off < UNC_SIZE; off += PAGE_SIZE) {
                                ret = snapshot_read_next(snapshot);
                                if (ret < 0)
                                        goto out_finish;

                                if (!ret)
                                        break;

                                memcpy(data[thr].unc + off,
                                       data_of(*snapshot), PAGE_SIZE);

                                if (!(nr_pages % m))
                                        pr_info("Image saving progress: %3d%%\n",
                                                nr_pages / m * 10);
                                nr_pages++;
                        }
                        if (!off)
                                break;

                        data[thr].unc_len = off;

                        atomic_set_release(&data[thr].ready, 1);
                        wake_up(&data[thr].go);
                }

                if (!thr)
                        break;

                crc->run_threads = thr;
                atomic_set_release(&crc->ready, 1);
                wake_up(&crc->go);

                for (run_threads = thr, thr = 0; thr < run_threads; thr++) {
                        wait_event(data[thr].done,
                                atomic_read_acquire(&data[thr].stop));
                        atomic_set(&data[thr].stop, 0);

                        ret = data[thr].ret;

                        if (ret < 0) {
                                pr_err("%s compression failed\n", hib_comp_algo);
                                goto out_finish;
                        }

                        if (unlikely(!data[thr].cmp_len ||
                                     data[thr].cmp_len >
                                     bytes_worst_compress(data[thr].unc_len))) {
                                pr_err("Invalid %s compressed length\n", hib_comp_algo);
                                ret = -1;
                                goto out_finish;
                        }

                        *(size_t *)data[thr].cmp = data[thr].cmp_len;

                        /*
                         * Given we are writing one page at a time to disk, we
                         * copy that much from the buffer, although the last
                         * bit will likely be smaller than full page. This is
                         * OK - we saved the length of the compressed data, so
                         * any garbage at the end will be discarded when we
                         * read it.
                         */
                        for (off = 0;
                             off < CMP_HEADER + data[thr].cmp_len;
                             off += PAGE_SIZE) {
                                memcpy(page, data[thr].cmp + off, PAGE_SIZE);

                                ret = swap_write_page(handle, page, &hb);
                                if (ret)
                                        goto out_finish;
                        }
                }

                wait_event(crc->done, atomic_read_acquire(&crc->stop));
                atomic_set(&crc->stop, 0);
        }

out_finish:
        err2 = hib_wait_io(&hb);
        stop = ktime_get();
        if (!ret)
                ret = err2;
        if (!ret) {
                swsusp_show_speed(start, stop, nr_to_write, "Wrote");
                pr_info("Image size after compression: %lld kbytes\n",
                        (atomic64_read(&compressed_size) / 1024));
                pr_info("Image saving done\n");
        } else {
                pr_err("Image saving failed: %d\n", ret);
        }

out_clean:
        hib_finish_batch(&hb);
        free_crc_data(crc);
        if (data) {
                for (thr = 0; thr < nr_threads; thr++) {
                        if (data[thr].thr)
                                kthread_stop(data[thr].thr);

                        acomp_request_free(data[thr].cr);

                        if (!IS_ERR_OR_NULL(data[thr].cc))
                                crypto_free_acomp(data[thr].cc);
                }
                vfree(data);
        }
        if (page)
                free_page((unsigned long)page);

        return ret;
}

static int enough_swap(unsigned int nr_pages)
{
        unsigned int free_swap = count_swap_pages(root_swap, 1);
        unsigned int required;

        pr_debug("Free swap pages: %u\n", free_swap);

        required = PAGES_FOR_IO + nr_pages;
        return free_swap > required;
}

/**
 * swsusp_write - Write entire image and metadata.
 * @flags: flags to pass to the "boot" kernel in the image header
 *
 * It is important _NOT_ to umount filesystems at this point. We want them
 * synced (in case something goes wrong) but we DO not want to mark filesystem
 * clean: it is not. (And it does not matter, if we resume correctly, we'll mark
 * system clean, anyway.)
 *
 * Return: 0 on success, negative error code on failure.
 */
int swsusp_write(unsigned int flags)
{
        struct swap_map_handle handle;
        struct snapshot_handle snapshot;
        struct swsusp_info *header;
        unsigned long pages;
        int error;

        pages = snapshot_get_image_size();
        error = get_swap_writer(&handle);
        if (error) {
                pr_err("Cannot get swap writer\n");
                return error;
        }
        if (flags & SF_NOCOMPRESS_MODE) {
                if (!enough_swap(pages)) {
                        pr_err("Not enough free swap\n");
                        error = -ENOSPC;
                        goto out_finish;
                }
        }
        memset(&snapshot, 0, sizeof(struct snapshot_handle));
        error = snapshot_read_next(&snapshot);
        if (error < (int)PAGE_SIZE) {
                if (error >= 0)
                        error = -EFAULT;

                goto out_finish;
        }
        header = (struct swsusp_info *)data_of(snapshot);
        error = swap_write_page(&handle, header, NULL);
        if (!error) {
                error = (flags & SF_NOCOMPRESS_MODE) ?
                        save_image(&handle, &snapshot, pages - 1) :
                        save_compressed_image(&handle, &snapshot, pages - 1);
        }
out_finish:
        error = swap_writer_finish(&handle, flags, error);
        return error;
}

/*
 * The following functions allow us to read data using a swap map in a file-like
 * way.
 */

static void release_swap_reader(struct swap_map_handle *handle)
{
        struct swap_map_page_list *tmp;

        while (handle->maps) {
                if (handle->maps->map)
                        free_page((unsigned long)handle->maps->map);
                tmp = handle->maps;
                handle->maps = handle->maps->next;
                kfree(tmp);
        }
        handle->cur = NULL;
}

static int get_swap_reader(struct swap_map_handle *handle,
                unsigned int *flags_p)
{
        int error;
        struct swap_map_page_list *tmp, *last;
        sector_t offset;

        *flags_p = swsusp_header->flags;

        if (!swsusp_header->image) /* how can this happen? */
                return -EINVAL;

        handle->cur = NULL;
        last = handle->maps = NULL;
        offset = swsusp_header->image;
        while (offset) {
                tmp = kzalloc_obj(*handle->maps);
                if (!tmp) {
                        release_swap_reader(handle);
                        return -ENOMEM;
                }
                if (!handle->maps)
                        handle->maps = tmp;
                if (last)
                        last->next = tmp;
                last = tmp;

                tmp->map = (struct swap_map_page *)
                           __get_free_page(GFP_NOIO | __GFP_HIGH);
                if (!tmp->map) {
                        release_swap_reader(handle);
                        return -ENOMEM;
                }

                error = hib_submit_io_sync(REQ_OP_READ, offset, tmp->map);
                if (error) {
                        release_swap_reader(handle);
                        return error;
                }
                offset = tmp->map->next_swap;
        }
        handle->k = 0;
        handle->cur = handle->maps->map;
        return 0;
}

static int swap_read_page(struct swap_map_handle *handle, void *buf,
                struct hib_bio_batch *hb)
{
        sector_t offset;
        int error;
        struct swap_map_page_list *tmp;

        if (!handle->cur)
                return -EINVAL;
        offset = handle->cur->entries[handle->k];
        if (!offset)
                return -EFAULT;
        if (hb)
                error = hib_submit_io_async(REQ_OP_READ, offset, buf, hb);
        else
                error = hib_submit_io_sync(REQ_OP_READ, offset, buf);
        if (error)
                return error;
        if (++handle->k >= MAP_PAGE_ENTRIES) {
                handle->k = 0;
                free_page((unsigned long)handle->maps->map);
                tmp = handle->maps;
                handle->maps = handle->maps->next;
                kfree(tmp);
                if (!handle->maps)
                        release_swap_reader(handle);
                else
                        handle->cur = handle->maps->map;
        }
        return error;
}

static int swap_reader_finish(struct swap_map_handle *handle)
{
        release_swap_reader(handle);

        return 0;
}

static int load_image(struct swap_map_handle *handle,
                      struct snapshot_handle *snapshot,
                      unsigned int nr_to_read)
{
        unsigned int m;
        int ret = 0;
        ktime_t start;
        ktime_t stop;
        struct hib_bio_batch hb;
        int err2;
        unsigned nr_pages;

        hib_init_batch(&hb);

        clean_pages_on_read = true;
        pr_info("Loading image data pages (%u pages)...\n", nr_to_read);
        m = nr_to_read / 10;
        if (!m)
                m = 1;
        nr_pages = 0;
        start = ktime_get();
        for ( ; ; ) {
                ret = snapshot_write_next(snapshot);
                if (ret <= 0)
                        break;
                ret = swap_read_page(handle, data_of(*snapshot), &hb);
                if (ret)
                        break;
                if (snapshot->sync_read)
                        ret = hib_wait_io(&hb);
                if (ret)
                        break;
                if (!(nr_pages % m))
                        pr_info("Image loading progress: %3d%%\n",
                                nr_pages / m * 10);
                nr_pages++;
        }
        err2 = hib_wait_io(&hb);
        hib_finish_batch(&hb);
        stop = ktime_get();
        if (!ret)
                ret = err2;
        if (!ret) {
                pr_info("Image loading done\n");
                ret = snapshot_write_finalize(snapshot);
                if (!ret && !snapshot_image_loaded(snapshot))
                        ret = -ENODATA;
        }
        swsusp_show_speed(start, stop, nr_to_read, "Read");
        return ret;
}

/*
 * Structure used for data decompression.
 */
struct dec_data {
        struct task_struct *thr;                  /* thread */
        struct crypto_acomp *cc;                  /* crypto compressor */
        struct acomp_req *cr;                     /* crypto request */
        atomic_t ready;                           /* ready to start flag */
        atomic_t stop;                            /* ready to stop flag */
        int ret;                                  /* return code */
        wait_queue_head_t go;                     /* start decompression */
        wait_queue_head_t done;                   /* decompression done */
        size_t unc_len;                           /* uncompressed length */
        size_t cmp_len;                           /* compressed length */
        unsigned char unc[UNC_SIZE];              /* uncompressed buffer */
        unsigned char cmp[CMP_SIZE];              /* compressed buffer */
};

static int decompress_threadfn(void *data)
{
        struct dec_data *d = data;

        while (1) {
                wait_event(d->go, atomic_read_acquire(&d->ready) ||
                                  kthread_should_stop());
                if (kthread_should_stop()) {
                        d->thr = NULL;
                        d->ret = -1;
                        atomic_set_release(&d->stop, 1);
                        wake_up(&d->done);
                        break;
                }
                atomic_set(&d->ready, 0);

                acomp_request_set_callback(d->cr, CRYPTO_TFM_REQ_MAY_SLEEP,
                                           NULL, NULL);
                acomp_request_set_src_nondma(d->cr, d->cmp + CMP_HEADER,
                                             d->cmp_len);
                acomp_request_set_dst_nondma(d->cr, d->unc, UNC_SIZE);
                d->ret = crypto_acomp_decompress(d->cr);
                d->unc_len = d->cr->dlen;

                if (clean_pages_on_decompress)
                        flush_icache_range((unsigned long)d->unc,
                                           (unsigned long)d->unc + d->unc_len);

                atomic_set_release(&d->stop, 1);
                wake_up(&d->done);
        }
        return 0;
}

static int load_compressed_image(struct swap_map_handle *handle,
                                 struct snapshot_handle *snapshot,
                                 unsigned int nr_to_read)
{
        unsigned int m;
        int ret = 0;
        int eof = 0;
        struct hib_bio_batch hb;
        ktime_t start;
        ktime_t stop;
        unsigned nr_pages;
        size_t off;
        unsigned i, thr, run_threads, nr_threads;
        unsigned ring = 0, pg = 0, ring_size = 0,
                 have = 0, want, need, asked = 0;
        unsigned long read_pages = 0;
        unsigned char **page = NULL;
        struct dec_data *data = NULL;
        struct crc_data *crc = NULL;

        hib_init_batch(&hb);

        /*
         * We'll limit the number of threads for decompression to limit memory
         * footprint.
         */
        nr_threads = num_online_cpus() - 1;
        nr_threads = clamp_val(nr_threads, 1, hibernate_compression_threads);

        page = vmalloc_array(CMP_MAX_RD_PAGES, sizeof(*page));
        if (!page) {
                pr_err("Failed to allocate %s page\n", hib_comp_algo);
                ret = -ENOMEM;
                goto out_clean;
        }

        data = vcalloc(nr_threads, sizeof(*data));
        if (!data) {
                pr_err("Failed to allocate %s data\n", hib_comp_algo);
                ret = -ENOMEM;
                goto out_clean;
        }

        crc = alloc_crc_data(nr_threads);
        if (!crc) {
                pr_err("Failed to allocate crc\n");
                ret = -ENOMEM;
                goto out_clean;
        }

        clean_pages_on_decompress = true;

        /*
         * Start the decompression threads.
         */
        for (thr = 0; thr < nr_threads; thr++) {
                init_waitqueue_head(&data[thr].go);
                init_waitqueue_head(&data[thr].done);

                data[thr].cc = crypto_alloc_acomp(hib_comp_algo, 0, CRYPTO_ALG_ASYNC);
                if (IS_ERR_OR_NULL(data[thr].cc)) {
                        pr_err("Could not allocate comp stream %ld\n", PTR_ERR(data[thr].cc));
                        ret = -EFAULT;
                        goto out_clean;
                }

                data[thr].cr = acomp_request_alloc(data[thr].cc);
                if (!data[thr].cr) {
                        pr_err("Could not allocate comp request\n");
                        ret = -ENOMEM;
                        goto out_clean;
                }

                data[thr].thr = kthread_run(decompress_threadfn,
                                            &data[thr],
                                            "image_decompress/%u", thr);
                if (IS_ERR(data[thr].thr)) {
                        data[thr].thr = NULL;
                        pr_err("Cannot start decompression threads\n");
                        ret = -ENOMEM;
                        goto out_clean;
                }
        }

        /*
         * Start the CRC32 thread.
         */
        init_waitqueue_head(&crc->go);
        init_waitqueue_head(&crc->done);

        handle->crc32 = 0;
        crc->crc32 = &handle->crc32;
        for (thr = 0; thr < nr_threads; thr++) {
                crc->unc[thr] = data[thr].unc;
                crc->unc_len[thr] = &data[thr].unc_len;
        }

        crc->thr = kthread_run(crc32_threadfn, crc, "image_crc32");
        if (IS_ERR(crc->thr)) {
                crc->thr = NULL;
                pr_err("Cannot start CRC32 thread\n");
                ret = -ENOMEM;
                goto out_clean;
        }

        /*
         * Set the number of pages for read buffering.
         * This is complete guesswork, because we'll only know the real
         * picture once prepare_image() is called, which is much later on
         * during the image load phase. We'll assume the worst case and
         * say that none of the image pages are from high memory.
         */
        if (low_free_pages() > snapshot_get_image_size())
                read_pages = (low_free_pages() - snapshot_get_image_size()) / 2;
        read_pages = clamp_val(read_pages, CMP_MIN_RD_PAGES, CMP_MAX_RD_PAGES);

        for (i = 0; i < read_pages; i++) {
                page[i] = (void *)__get_free_page(i < CMP_PAGES ?
                                                  GFP_NOIO | __GFP_HIGH :
                                                  GFP_NOIO | __GFP_NOWARN |
                                                  __GFP_NORETRY);

                if (!page[i]) {
                        if (i < CMP_PAGES) {
                                ring_size = i;
                                pr_err("Failed to allocate %s pages\n", hib_comp_algo);
                                ret = -ENOMEM;
                                goto out_clean;
                        } else {
                                break;
                        }
                }
        }
        want = ring_size = i;

        pr_info("Using %u thread(s) for %s decompression\n", nr_threads, hib_comp_algo);
        pr_info("Loading and decompressing image data (%u pages)...\n",
                nr_to_read);
        m = nr_to_read / 10;
        if (!m)
                m = 1;
        nr_pages = 0;
        start = ktime_get();

        ret = snapshot_write_next(snapshot);
        if (ret <= 0)
                goto out_finish;

        for(;;) {
                for (i = 0; !eof && i < want; i++) {
                        ret = swap_read_page(handle, page[ring], &hb);
                        if (ret) {
                                /*
                                 * On real read error, finish. On end of data,
                                 * set EOF flag and just exit the read loop.
                                 */
                                if (handle->cur &&
                                    handle->cur->entries[handle->k]) {
                                        goto out_finish;
                                } else {
                                        eof = 1;
                                        break;
                                }
                        }
                        if (++ring >= ring_size)
                                ring = 0;
                }
                asked += i;
                want -= i;

                /*
                 * We are out of data, wait for some more.
                 */
                if (!have) {
                        if (!asked)
                                break;

                        ret = hib_wait_io(&hb);
                        if (ret)
                                goto out_finish;
                        have += asked;
                        asked = 0;
                        if (eof)
                                eof = 2;
                }

                if (crc->run_threads) {
                        wait_event(crc->done, atomic_read_acquire(&crc->stop));
                        atomic_set(&crc->stop, 0);
                        crc->run_threads = 0;
                }

                for (thr = 0; have && thr < nr_threads; thr++) {
                        data[thr].cmp_len = *(size_t *)page[pg];
                        if (unlikely(!data[thr].cmp_len ||
                                     data[thr].cmp_len >
                                        bytes_worst_compress(UNC_SIZE))) {
                                pr_err("Invalid %s compressed length\n", hib_comp_algo);
                                ret = -1;
                                goto out_finish;
                        }

                        need = DIV_ROUND_UP(data[thr].cmp_len + CMP_HEADER,
                                            PAGE_SIZE);
                        if (need > have) {
                                if (eof > 1) {
                                        ret = -1;
                                        goto out_finish;
                                }
                                break;
                        }

                        for (off = 0;
                             off < CMP_HEADER + data[thr].cmp_len;
                             off += PAGE_SIZE) {
                                memcpy(data[thr].cmp + off,
                                       page[pg], PAGE_SIZE);
                                have--;
                                want++;
                                if (++pg >= ring_size)
                                        pg = 0;
                        }

                        atomic_set_release(&data[thr].ready, 1);
                        wake_up(&data[thr].go);
                }

                /*
                 * Wait for more data while we are decompressing.
                 */
                if (have < CMP_PAGES && asked) {
                        ret = hib_wait_io(&hb);
                        if (ret)
                                goto out_finish;
                        have += asked;
                        asked = 0;
                        if (eof)
                                eof = 2;
                }

                for (run_threads = thr, thr = 0; thr < run_threads; thr++) {
                        wait_event(data[thr].done,
                                atomic_read_acquire(&data[thr].stop));
                        atomic_set(&data[thr].stop, 0);

                        ret = data[thr].ret;

                        if (ret < 0) {
                                pr_err("%s decompression failed\n", hib_comp_algo);
                                goto out_finish;
                        }

                        if (unlikely(!data[thr].unc_len ||
                                data[thr].unc_len > UNC_SIZE ||
                                data[thr].unc_len & (PAGE_SIZE - 1))) {
                                pr_err("Invalid %s uncompressed length\n", hib_comp_algo);
                                ret = -1;
                                goto out_finish;
                        }

                        for (off = 0;
                             off < data[thr].unc_len; off += PAGE_SIZE) {
                                memcpy(data_of(*snapshot),
                                       data[thr].unc + off, PAGE_SIZE);

                                if (!(nr_pages % m))
                                        pr_info("Image loading progress: %3d%%\n",
                                                nr_pages / m * 10);
                                nr_pages++;

                                ret = snapshot_write_next(snapshot);
                                if (ret <= 0) {
                                        crc->run_threads = thr + 1;
                                        atomic_set_release(&crc->ready, 1);
                                        wake_up(&crc->go);
                                        goto out_finish;
                                }
                        }
                }

                crc->run_threads = thr;
                atomic_set_release(&crc->ready, 1);
                wake_up(&crc->go);
        }

out_finish:
        if (crc->run_threads) {
                wait_event(crc->done, atomic_read_acquire(&crc->stop));
                atomic_set(&crc->stop, 0);
        }
        stop = ktime_get();
        if (!ret) {
                pr_info("Image loading done\n");
                ret = snapshot_write_finalize(snapshot);
                if (!ret && !snapshot_image_loaded(snapshot))
                        ret = -ENODATA;
                if (!ret) {
                        if (swsusp_header->flags & SF_CRC32_MODE) {
                                if(handle->crc32 != swsusp_header->crc32) {
                                        pr_err("Invalid image CRC32!\n");
                                        ret = -ENODATA;
                                }
                        }
                }
        }
        swsusp_show_speed(start, stop, nr_to_read, "Read");
out_clean:
        hib_finish_batch(&hb);
        for (i = 0; i < ring_size; i++)
                free_page((unsigned long)page[i]);
        free_crc_data(crc);
        if (data) {
                for (thr = 0; thr < nr_threads; thr++) {
                        if (data[thr].thr)
                                kthread_stop(data[thr].thr);

                        acomp_request_free(data[thr].cr);

                        if (!IS_ERR_OR_NULL(data[thr].cc))
                                crypto_free_acomp(data[thr].cc);
                }
                vfree(data);
        }
        vfree(page);

        return ret;
}

/**
 *      swsusp_read - read the hibernation image.
 *      @flags_p: flags passed by the "frozen" kernel in the image header should
 *                be written into this memory location
 *
 *      Return: 0 on success, negative error code on failure.
 */
int swsusp_read(unsigned int *flags_p)
{
        int error;
        struct swap_map_handle handle;
        struct snapshot_handle snapshot;
        struct swsusp_info *header;

        memset(&snapshot, 0, sizeof(struct snapshot_handle));
        error = snapshot_write_next(&snapshot);
        if (error < (int)PAGE_SIZE)
                return error < 0 ? error : -EFAULT;
        header = (struct swsusp_info *)data_of(snapshot);
        error = get_swap_reader(&handle, flags_p);
        if (error)
                goto end;
        if (!error)
                error = swap_read_page(&handle, header, NULL);
        if (!error) {
                error = (*flags_p & SF_NOCOMPRESS_MODE) ?
                        load_image(&handle, &snapshot, header->pages - 1) :
                        load_compressed_image(&handle, &snapshot, header->pages - 1);
        }
        swap_reader_finish(&handle);
end:
        if (!error)
                pr_debug("Image successfully loaded\n");
        else
                pr_debug("Error %d resuming\n", error);
        return error;
}

static void *swsusp_holder;

/**
 * swsusp_check - Open the resume device and check for the swsusp signature.
 * @exclusive: Open the resume device exclusively.
 *
 * Return: 0 if a valid image is found, negative error code otherwise.
 */
int swsusp_check(bool exclusive)
{
        void *holder = exclusive ? &swsusp_holder : NULL;
        int error;

        hib_resume_bdev_file = bdev_file_open_by_dev(swsusp_resume_device,
                                BLK_OPEN_READ, holder, NULL);
        if (!IS_ERR(hib_resume_bdev_file)) {
                clear_page(swsusp_header);
                error = hib_submit_io_sync(REQ_OP_READ, swsusp_resume_block,
                                        swsusp_header);
                if (error)
                        goto put;

                if (!memcmp(HIBERNATE_SIG, swsusp_header->sig, 10)) {
                        memcpy(swsusp_header->sig, swsusp_header->orig_sig, 10);
                        swsusp_header_flags = swsusp_header->flags;
                        /* Reset swap signature now */
                        error = hib_submit_io_sync(REQ_OP_WRITE | REQ_SYNC,
                                                swsusp_resume_block,
                                                swsusp_header);
                } else {
                        error = -EINVAL;
                }
                if (!error && swsusp_header->flags & SF_HW_SIG &&
                    swsusp_header->hw_sig != swsusp_hardware_signature) {
                        pr_info("Suspend image hardware signature mismatch (%08x now %08x); aborting resume.\n",
                                swsusp_header->hw_sig, swsusp_hardware_signature);
                        error = -EINVAL;
                }

put:
                if (error)
                        bdev_fput(hib_resume_bdev_file);
                else
                        pr_debug("Image signature found, resuming\n");
        } else {
                error = PTR_ERR(hib_resume_bdev_file);
        }

        if (error)
                pr_debug("Image not found (code %d)\n", error);

        return error;
}

/**
 * swsusp_close - close resume device.
 */
void swsusp_close(void)
{
        if (IS_ERR(hib_resume_bdev_file)) {
                pr_debug("Image device not initialised\n");
                return;
        }

        fput(hib_resume_bdev_file);
}

/**
 * swsusp_unmark - Unmark swsusp signature in the resume device
 *
 * Return: 0 on success, negative error code on failure.
 */
#ifdef CONFIG_SUSPEND
int swsusp_unmark(void)
{
        int error;

        hib_submit_io_sync(REQ_OP_READ, swsusp_resume_block, swsusp_header);
        if (!memcmp(HIBERNATE_SIG,swsusp_header->sig, 10)) {
                memcpy(swsusp_header->sig,swsusp_header->orig_sig, 10);
                error = hib_submit_io_sync(REQ_OP_WRITE | REQ_SYNC,
                                        swsusp_resume_block,
                                        swsusp_header);
        } else {
                pr_err("Cannot find swsusp signature!\n");
                error = -ENODEV;
        }

        /*
         * We just returned from suspend, we don't need the image any more.
         */
        free_all_swap_pages(root_swap);

        return error;
}
#endif

static ssize_t hibernate_compression_threads_show(struct kobject *kobj,
                                struct kobj_attribute *attr, char *buf)
{
        return sysfs_emit(buf, "%d\n", hibernate_compression_threads);
}

static ssize_t hibernate_compression_threads_store(struct kobject *kobj,
                                struct kobj_attribute *attr,
                                const char *buf, size_t n)
{
        unsigned long val;

        if (kstrtoul(buf, 0, &val))
                return -EINVAL;

        if (val < 1)
                return -EINVAL;

        hibernate_compression_threads = val;
        return n;
}
power_attr(hibernate_compression_threads);

static struct attribute *g[] = {
        &hibernate_compression_threads_attr.attr,
        NULL,
};

static const struct attribute_group attr_group = {
        .attrs = g,
};

static int __init swsusp_header_init(void)
{
        int error;

        error = sysfs_create_group(power_kobj, &attr_group);
        if (error)
                return -ENOMEM;

        swsusp_header = (struct swsusp_header*) __get_free_page(GFP_KERNEL);
        if (!swsusp_header)
                panic("Could not allocate memory for swsusp_header\n");
        return 0;
}

core_initcall(swsusp_header_init);

static int __init hibernate_compression_threads_setup(char *str)
{
        int rc = kstrtouint(str, 0, &hibernate_compression_threads);

        if (rc)
                return rc;

        if (hibernate_compression_threads < 1)
                hibernate_compression_threads = CMP_THREADS;

        return 1;

}

__setup("hibernate_compression_threads=", hibernate_compression_threads_setup);