[PATCH] PM / Hibernate: Migrate to ktime_t

Tina Ruchandani
2014-10-30T18:04:58Z

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>

--
Changes in v4:
- Rebased patch off of 3.18-rc1
Changes in v3:
- Use monotonic clock (ktime_get())
instead of ktime_get_real()
- Fix incorrect denominator in ktime_divns
Changes in v2:
- Incorporate whitespace fixes suggested by
Arnd Bergmann <arnd@arndb.de>
- Use ktime_divns instead of ktime_to_ns and
then do_div to get centisecs
- Explain reason for changing elapsed_centisecs
to u64.
---
kernel/power/hibernate.c | 14 ++++++--------
kernel/power/power.h | 3 +--
kernel/power/snapshot.c | 9 +++++----
kernel/power/swap.c | 41 +++++++++++++++++++++--------------------
4 files changed, 33 insertions(+), 34 deletions(-)

diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index a9dfa79..6e6cb96 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 2df883a..ce9b832 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 791a618..0c40c16 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 aaa3261..2c9d6d5 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]);
--
2.1.0.rc2.206.gedb03e5