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Subject[PATCH v2 1/3] kernel/time: Add new helpers to convert ktime to/from jiffies
Date
From: Anton Vorontsov <anton@scarybugs.org>

Two new functions: jiffies_to_ktime() and ktime_to_jiffies(), we'll use
them for timerfd deferred timers handling.

We fully reuse the logic from timespec implementations, so the functions
are pretty straightforward.

The only tricky part is in headers: we have to include jiffies.h after
we defined ktime_t, this is because ktime.h needs some declarations from
jiffies.h (e.g. TICK_NSEC).

Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: Alexey Perevalov <a.perevalov@samsung.com>
---
include/linux/jiffies.h | 4 +++-
include/linux/ktime.h | 3 ++-
kernel/time.c | 23 +++++++++++++++++++++++
3 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/include/linux/jiffies.h b/include/linux/jiffies.h
index d235e88..1ba02ae 100644
--- a/include/linux/jiffies.h
+++ b/include/linux/jiffies.h
@@ -6,6 +6,7 @@
#include <linux/types.h>
#include <linux/time.h>
#include <linux/timex.h>
+#include <linux/ktime.h>
#include <asm/param.h> /* for HZ */

/*
@@ -302,7 +303,8 @@ extern void jiffies_to_timespec(const unsigned long jiffies,
extern unsigned long timeval_to_jiffies(const struct timeval *value);
extern void jiffies_to_timeval(const unsigned long jiffies,
struct timeval *value);
-
+extern unsigned long ktime_to_jiffies(ktime_t *value);
+extern void jiffies_to_ktime(const unsigned long jiffies, ktime_t *value);
extern clock_t jiffies_to_clock_t(unsigned long x);
static inline clock_t jiffies_delta_to_clock_t(long delta)
{
diff --git a/include/linux/ktime.h b/include/linux/ktime.h
index 31c0cd1..e8ed619 100644
--- a/include/linux/ktime.h
+++ b/include/linux/ktime.h
@@ -22,7 +22,6 @@
#define _LINUX_KTIME_H

#include <linux/time.h>
-#include <linux/jiffies.h>

/*
* ktime_t:
@@ -58,6 +57,8 @@ union ktime {

typedef union ktime ktime_t; /* Kill this */

+#include <linux/jiffies.h>
+
/*
* ktime_t definitions when using the 64-bit scalar representation:
*/
diff --git a/kernel/time.c b/kernel/time.c
index 7c7964c..22580a0 100644
--- a/kernel/time.c
+++ b/kernel/time.c
@@ -29,6 +29,7 @@

#include <linux/export.h>
#include <linux/timex.h>
+#include <linux/ktime.h>
#include <linux/capability.h>
#include <linux/timekeeper_internal.h>
#include <linux/errno.h>
@@ -575,6 +576,28 @@ void jiffies_to_timeval(const unsigned long jiffies, struct timeval *value)
}
EXPORT_SYMBOL(jiffies_to_timeval);

+unsigned long ktime_to_jiffies(ktime_t *value)
+{
+ struct timespec ts = ktime_to_timespec(*value);
+
+ /*
+ * nsecs_to_jiffies(ktime_to_ns(*ktime)) is unsafe as nsecs_to_jiffies
+ * doesn't handle MAX_JIFFY_OFFSET. So we reuse the logic from the
+ * timespec to jiffies conversion function.
+ */
+ return timespec_to_jiffies(&ts);
+}
+EXPORT_SYMBOL(ktime_to_jiffies);
+
+void jiffies_to_ktime(const unsigned long jiffies, ktime_t *value)
+{
+ struct timespec ts;
+
+ jiffies_to_timespec(jiffies, &ts);
+ *value = timespec_to_ktime(ts);
+}
+EXPORT_SYMBOL(jiffies_to_ktime);
+
/*
* Convert jiffies/jiffies_64 to clock_t and back.
*/
--
1.7.9.5


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