[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 dae7143644fe8b87c18aa1fb57e175d6f61865c2..a6ddec141f96c83752ddb060079d0efa4e517aa4 100644 (file)
--- a/include/linux/ktime.h
+++ b/include/linux/ktime.h
@@ -102,6 +102,13 @@ static inline ktime_t ktime_set(const long secs, const unsigned long nsecs)
 #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)
 {
@@ -199,6 +206,15 @@ static inline ktime_t ktime_add(const ktime_t add1, const ktime_t add2)
  */
 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 @@ static inline ktime_t ktime_add_us(const ktime_t kt, const u64 usec)
        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 c21ca6bfaa6600dd864ef1b32798dc1a4ae8c081..dc8a4451d79b15d64a37caf55c9dc4595c6ec5d2 100644 (file)
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -277,6 +277,30 @@ ktime_t ktime_add_ns(const ktime_t kt, u64 nsec)
 }
 
 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 */
 
 /*