PM / Hibernate: Migrate to ktime_t

This patch migrates swsusp_show_speed and its callers to using ktime_t instead
of 'struct timeval' which suffers from the y2038 problem.

Changes to swsusp_show_speed:
        - use ktime_t for start and stop times
        - pass start and stop times by value
Calling functions affected:
        - load_image
        - load_image_lzo
        - save_image
        - save_image_lzo
        - hibernate_preallocate_memory
Design decisions:
        - use ktime_t to preserve same granularity of reporting as before
        - use centisecs logic as before to avoid 'div by zero' issues caused by
          using seconds and nanoseconds directly
        - use monotonic time (ktime_get()) since we only care about elapsed time.

Signed-off-by: Tina Ruchandani <ruchandani.tina@gmail.com>
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

4 files changed, 33 insertions, 34 deletions

diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index 1f35a3478f3c..2329daae5255 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -28,6 +28,7 @@
 #include <linux/syscore_ops.h>
 #include <linux/ctype.h>
 #include <linux/genhd.h>
+#include <linux/ktime.h>
 #include <trace/events/power.h>
 
 #include "power.h"
@@ -232,20 +233,17 @@ static void platform_recover(int platform_mode)
  * @nr_pages: Number of memory pages processed between @start and @stop.
  * @msg: Additional diagnostic message to print.
  */
-void swsusp_show_speed(struct timeval *start, struct timeval *stop,
-                        unsigned nr_pages, char *msg)
+void swsusp_show_speed(ktime_t start, ktime_t stop,
+                      unsigned nr_pages, char *msg)
 {
+        ktime_t diff;
         u64 elapsed_centisecs64;
         unsigned int centisecs;
         unsigned int k;
         unsigned int kps;
 
-        elapsed_centisecs64 = timeval_to_ns(stop) - timeval_to_ns(start);
-        /*
-         * If "(s64)elapsed_centisecs64 < 0", it will print long elapsed time,
-         * it is obvious enough for what went wrong.
-         */
-        do_div(elapsed_centisecs64, NSEC_PER_SEC / 100);
+        diff = ktime_sub(stop, start);
+        elapsed_centisecs64 = ktime_divns(diff, 10*NSEC_PER_MSEC);
         centisecs = elapsed_centisecs64;
         if (centisecs == 0)
                 centisecs = 1;  /* avoid div-by-zero */
diff --git a/kernel/power/power.h b/kernel/power/power.h
index 2df883a9d3cb..ce9b8328a689 100644
--- a/kernel/power/power.h
+++ b/kernel/power/power.h
@@ -174,8 +174,7 @@ extern int hib_wait_on_bio_chain(struct bio **bio_chain);
 
 struct timeval;
 /* kernel/power/swsusp.c */
-extern void swsusp_show_speed(struct timeval *, struct timeval *,
-                                unsigned int, char *);
+extern void swsusp_show_speed(ktime_t, ktime_t, unsigned int, char *);
 
 #ifdef CONFIG_SUSPEND
 /* kernel/power/suspend.c */
diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index 791a61892bb5..0c40c16174b4 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -28,6 +28,7 @@
 #include <linux/list.h>
 #include <linux/slab.h>
 #include <linux/compiler.h>
+#include <linux/ktime.h>
 
 #include <asm/uaccess.h>
 #include <asm/mmu_context.h>
@@ -1576,11 +1577,11 @@ int hibernate_preallocate_memory(void)
         struct zone *zone;
         unsigned long saveable, size, max_size, count, highmem, pages = 0;
         unsigned long alloc, save_highmem, pages_highmem, avail_normal;
-        struct timeval start, stop;
+        ktime_t start, stop;
         int error;
 
         printk(KERN_INFO "PM: Preallocating image memory... ");
-        do_gettimeofday(&start);
+        start = ktime_get();
 
         error = memory_bm_create(&orig_bm, GFP_IMAGE, PG_ANY);
         if (error)
@@ -1709,9 +1710,9 @@ int hibernate_preallocate_memory(void)
         free_unnecessary_pages();
 
  out:
-        do_gettimeofday(&stop);
+        stop = ktime_get();
         printk(KERN_CONT "done (allocated %lu pages)\n", pages);
-        swsusp_show_speed(&start, &stop, pages, "Allocated");
+        swsusp_show_speed(start, stop, pages, "Allocated");
 
         return 0;
 
diff --git a/kernel/power/swap.c b/kernel/power/swap.c
index aaa3261dea5d..2c9d6d50a816 100644
--- a/kernel/power/swap.c
+++ b/kernel/power/swap.c
@@ -30,6 +30,7 @@
 #include <linux/atomic.h>
 #include <linux/kthread.h>
 #include <linux/crc32.h>
+#include <linux/ktime.h>
 
 #include "power.h"
 
@@ -445,8 +446,8 @@ static int save_image(struct swap_map_handle *handle,
         int nr_pages;
         int err2;
         struct bio *bio;
-        struct timeval start;
-        struct timeval stop;
+        ktime_t start;
+        ktime_t stop;
 
         printk(KERN_INFO "PM: Saving image data pages (%u pages)...\n",
                 nr_to_write);
@@ -455,7 +456,7 @@ static int save_image(struct swap_map_handle *handle,
                 m = 1;
         nr_pages = 0;
         bio = NULL;
-        do_gettimeofday(&start);
+        start = ktime_get();
         while (1) {
                 ret = snapshot_read_next(snapshot);
                 if (ret <= 0)
@@ -469,12 +470,12 @@ static int save_image(struct swap_map_handle *handle,
                 nr_pages++;
         }
         err2 = hib_wait_on_bio_chain(&bio);
-        do_gettimeofday(&stop);
+        stop = ktime_get();
         if (!ret)
                 ret = err2;
         if (!ret)
                 printk(KERN_INFO "PM: Image saving done.\n");
-        swsusp_show_speed(&start, &stop, nr_to_write, "Wrote");
+        swsusp_show_speed(start, stop, nr_to_write, "Wrote");
         return ret;
 }
 
@@ -580,8 +581,8 @@ static int save_image_lzo(struct swap_map_handle *handle,
         int nr_pages;
         int err2;
         struct bio *bio;
-        struct timeval start;
-        struct timeval stop;
+        ktime_t start;
+        ktime_t stop;
         size_t off;
         unsigned thr, run_threads, nr_threads;
         unsigned char *page = NULL;
@@ -674,7 +675,7 @@ static int save_image_lzo(struct swap_map_handle *handle,
                 m = 1;
         nr_pages = 0;
         bio = NULL;
-        do_gettimeofday(&start);
+        start = ktime_get();
         for (;;) {
                 for (thr = 0; thr < nr_threads; thr++) {
                         for (off = 0; off < LZO_UNC_SIZE; off += PAGE_SIZE) {
@@ -759,12 +760,12 @@ static int save_image_lzo(struct swap_map_handle *handle,
 
 out_finish:
         err2 = hib_wait_on_bio_chain(&bio);
-        do_gettimeofday(&stop);
+        stop = ktime_get();
         if (!ret)
                 ret = err2;
         if (!ret)
                 printk(KERN_INFO "PM: Image saving done.\n");
-        swsusp_show_speed(&start, &stop, nr_to_write, "Wrote");
+        swsusp_show_speed(start, stop, nr_to_write, "Wrote");
 out_clean:
         if (crc) {
                 if (crc->thr)
@@ -965,8 +966,8 @@ static int load_image(struct swap_map_handle *handle,
 {
         unsigned int m;
         int ret = 0;
-        struct timeval start;
-        struct timeval stop;
+        ktime_t start;
+        ktime_t stop;
         struct bio *bio;
         int err2;
         unsigned nr_pages;
@@ -978,7 +979,7 @@ static int load_image(struct swap_map_handle *handle,
                 m = 1;
         nr_pages = 0;
         bio = NULL;
-        do_gettimeofday(&start);
+        start = ktime_get();
         for ( ; ; ) {
                 ret = snapshot_write_next(snapshot);
                 if (ret <= 0)
@@ -996,7 +997,7 @@ static int load_image(struct swap_map_handle *handle,
                 nr_pages++;
         }
         err2 = hib_wait_on_bio_chain(&bio);
-        do_gettimeofday(&stop);
+        stop = ktime_get();
         if (!ret)
                 ret = err2;
         if (!ret) {
@@ -1005,7 +1006,7 @@ static int load_image(struct swap_map_handle *handle,
                 if (!snapshot_image_loaded(snapshot))
                         ret = -ENODATA;
         }
-        swsusp_show_speed(&start, &stop, nr_to_read, "Read");
+        swsusp_show_speed(start, stop, nr_to_read, "Read");
         return ret;
 }
 
@@ -1067,8 +1068,8 @@ static int load_image_lzo(struct swap_map_handle *handle,
         int ret = 0;
         int eof = 0;
         struct bio *bio;
-        struct timeval start;
-        struct timeval stop;
+        ktime_t start;
+        ktime_t stop;
         unsigned nr_pages;
         size_t off;
         unsigned i, thr, run_threads, nr_threads;
@@ -1190,7 +1191,7 @@ static int load_image_lzo(struct swap_map_handle *handle,
                 m = 1;
         nr_pages = 0;
         bio = NULL;
-        do_gettimeofday(&start);
+        start = ktime_get();
 
         ret = snapshot_write_next(snapshot);
         if (ret <= 0)
@@ -1343,7 +1344,7 @@ out_finish:
                 wait_event(crc->done, atomic_read(&crc->stop));
                 atomic_set(&crc->stop, 0);
         }
-        do_gettimeofday(&stop);
+        stop = ktime_get();
         if (!ret) {
                 printk(KERN_INFO "PM: Image loading done.\n");
                 snapshot_write_finalize(snapshot);
@@ -1359,7 +1360,7 @@ out_finish:
                         }
                 }
         }
-        swsusp_show_speed(&start, &stop, nr_to_read, "Read");
+        swsusp_show_speed(start, stop, nr_to_read, "Read");
 out_clean:
         for (i = 0; i < ring_size; i++)
                 free_page((unsigned long)page[i]);