[TCP]: Congestion control API RTT sampling fix

Commit 164891aadf1721fca4dce473bb0e0998181537c6 broke RTT
sampling of congestion control modules. Inaccurate timestamps
could be fed to them without providing any way for them to
identify such cases. Previously RTT sampler was called only if
FLAG_RETRANS_DATA_ACKED was not set filtering inaccurate
timestamps nicely. In addition, the new behavior could give an
invalid timestamp (zero) to RTT sampler if only skbs with
TCPCB_RETRANS were ACKed. This solves both problems.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 12 insertions, 0 deletions

diff --git a/include/linux/ktime.h b/include/linux/ktime.h
index c762954bda14..2b139f66027f 100644
--- a/include/linux/ktime.h
+++ b/include/linux/ktime.h
@@ -261,6 +261,18 @@ static inline s64 ktime_to_ns(const ktime_t kt)
 
 #endif
 
+/**
+ * ktime_equal - Compares two ktime_t variables to see if they are equal
+ * @cmp1:       comparable1
+ * @cmp2:       comparable2
+ *
+ * Compare two ktime_t variables, returns 1 if equal
+ */
+static inline int ktime_equal(const ktime_t cmp1, const ktime_t cmp2)
+{
+        return cmp1.tv64 == cmp2.tv64;
+}
+
 static inline s64 ktime_to_us(const ktime_t kt)
 {
         struct timeval tv = ktime_to_timeval(kt);