[PATCH 4.9 02/59] time: Introduce jiffies64_to_nsecs()

From: Greg Kroah-Hartman
Date: Mon Oct 08 2018 - 14:38:32 EST


4.9-stable review patch. If anyone has any objections, please let me know.

------------------

From: Frederic Weisbecker <fweisbec@xxxxxxxxx>

commit 07e5f5e353aaa61696c8353d87050994a0c4648a upstream.

This will be needed for the cputime_t to nsec conversion.

Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Stanislaw Gruszka <sgruszka@xxxxxxxxxx>
Cc: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1485832191-26889-2-git-send-email-fweisbec@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Ivan Delalande <colona@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
include/linux/jiffies.h | 2 ++
kernel/time/time.c | 10 ++++++++++
kernel/time/timeconst.bc | 6 ++++++
3 files changed, 18 insertions(+)

--- a/include/linux/jiffies.h
+++ b/include/linux/jiffies.h
@@ -292,6 +292,8 @@ static inline u64 jiffies_to_nsecs(const
return (u64)jiffies_to_usecs(j) * NSEC_PER_USEC;
}

+extern u64 jiffies64_to_nsecs(u64 j);
+
extern unsigned long __msecs_to_jiffies(const unsigned int m);
#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
/*
--- a/kernel/time/time.c
+++ b/kernel/time/time.c
@@ -704,6 +704,16 @@ u64 nsec_to_clock_t(u64 x)
#endif
}

+u64 jiffies64_to_nsecs(u64 j)
+{
+#if !(NSEC_PER_SEC % HZ)
+ return (NSEC_PER_SEC / HZ) * j;
+# else
+ return div_u64(j * HZ_TO_NSEC_NUM, HZ_TO_NSEC_DEN);
+#endif
+}
+EXPORT_SYMBOL(jiffies64_to_nsecs);
+
/**
* nsecs_to_jiffies64 - Convert nsecs in u64 to jiffies64
*
--- a/kernel/time/timeconst.bc
+++ b/kernel/time/timeconst.bc
@@ -98,6 +98,12 @@ define timeconst(hz) {
print "#define HZ_TO_USEC_DEN\t\t", hz/cd, "\n"
print "#define USEC_TO_HZ_NUM\t\t", hz/cd, "\n"
print "#define USEC_TO_HZ_DEN\t\t", 1000000/cd, "\n"
+
+ cd=gcd(hz,1000000000)
+ print "#define HZ_TO_NSEC_NUM\t\t", 1000000000/cd, "\n"
+ print "#define HZ_TO_NSEC_DEN\t\t", hz/cd, "\n"
+ print "#define NSEC_TO_HZ_NUM\t\t", hz/cd, "\n"
+ print "#define NSEC_TO_HZ_DEN\t\t", 1000000000/cd, "\n"
print "\n"

print "#endif /* KERNEL_TIMECONST_H */\n"