[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/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 */
/*