[KTIME]: Introduce ktime_sub_ns and ktime_sub_us
First user will be the DCCP transport networking protocol.
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/ktime.h b/include/linux/ktime.h
index dae7143..a6ddec1 100644
--- a/include/linux/ktime.h
+++ b/include/linux/ktime.h
@@ -102,6 +102,13 @@
#define ktime_add_ns(kt, nsval) \
({ (ktime_t){ .tv64 = (kt).tv64 + (nsval) }; })
+/*
+ * Subtract a scalar nanosecod from a ktime_t variable
+ * res = kt - nsval:
+ */
+#define ktime_sub_ns(kt, nsval) \
+ ({ (ktime_t){ .tv64 = (kt).tv64 - (nsval) }; })
+
/* convert a timespec to ktime_t format: */
static inline ktime_t timespec_to_ktime(struct timespec ts)
{
@@ -200,6 +207,15 @@
extern ktime_t ktime_add_ns(const ktime_t kt, u64 nsec);
/**
+ * ktime_sub_ns - Subtract a scalar nanoseconds value from a ktime_t variable
+ * @kt: minuend
+ * @nsec: the scalar nsec value to subtract
+ *
+ * Returns the subtraction of @nsec from @kt in ktime_t format
+ */
+extern ktime_t ktime_sub_ns(const ktime_t kt, u64 nsec);
+
+/**
* timespec_to_ktime - convert a timespec to ktime_t format
* @ts: the timespec variable to convert
*
@@ -289,6 +305,11 @@
return ktime_add_ns(kt, usec * 1000);
}
+static inline ktime_t ktime_sub_us(const ktime_t kt, const u64 usec)
+{
+ return ktime_sub_ns(kt, usec * 1000);
+}
+
/*
* The resolution of the clocks. The resolution value is returned in
* the clock_getres() system call to give application programmers an
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index c21ca6b..dc8a445 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -277,6 +277,30 @@
}
EXPORT_SYMBOL_GPL(ktime_add_ns);
+
+/**
+ * ktime_sub_ns - Subtract a scalar nanoseconds value from a ktime_t variable
+ * @kt: minuend
+ * @nsec: the scalar nsec value to subtract
+ *
+ * Returns the subtraction of @nsec from @kt in ktime_t format
+ */
+ktime_t ktime_sub_ns(const ktime_t kt, u64 nsec)
+{
+ ktime_t tmp;
+
+ if (likely(nsec < NSEC_PER_SEC)) {
+ tmp.tv64 = nsec;
+ } else {
+ unsigned long rem = do_div(nsec, NSEC_PER_SEC);
+
+ tmp = ktime_set((long)nsec, rem);
+ }
+
+ return ktime_sub(kt, tmp);
+}
+
+EXPORT_SYMBOL_GPL(ktime_sub_ns);
# endif /* !CONFIG_KTIME_SCALAR */
/*