ip: Use inline function dst_metric() instead of direct access to dst->metric[]

There are functions to refer to the value of dst->metric[THE_METRIC-1]
directly without use of a inline function "dst_metric" defined in
net/dst.h.

The following patch changes them to use the inline function
consistently.

Signed-off-by: Satoru SATOH <satoru.satoh@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index eda4f4a..8ac15a6 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -66,6 +66,7 @@
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/sysctl.h>
+#include <net/dst.h>
 #include <net/tcp.h>
 #include <net/inet_common.h>
 #include <linux/ipsec.h>
@@ -605,7 +606,7 @@
 	u32 rto_min = TCP_RTO_MIN;
 
 	if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
-		rto_min = dst->metrics[RTAX_RTO_MIN - 1];
+		rto_min = dst_metric(dst, RTAX_RTO_MIN);
 	return rto_min;
 }
 
@@ -769,7 +770,7 @@
 				dst->metrics[RTAX_RTTVAR - 1] = m;
 			else
 				dst->metrics[RTAX_RTTVAR-1] -=
-					(dst->metrics[RTAX_RTTVAR-1] - m)>>2;
+					(dst_metric(dst, RTAX_RTTVAR) - m)>>2;
 		}
 
 		if (tp->snd_ssthresh >= 0xFFFF) {
@@ -788,21 +789,21 @@
 				dst->metrics[RTAX_SSTHRESH-1] =
 					max(tp->snd_cwnd >> 1, tp->snd_ssthresh);
 			if (!dst_metric_locked(dst, RTAX_CWND))
-				dst->metrics[RTAX_CWND-1] = (dst->metrics[RTAX_CWND-1] + tp->snd_cwnd) >> 1;
+				dst->metrics[RTAX_CWND-1] = (dst_metric(dst, RTAX_CWND) + tp->snd_cwnd) >> 1;
 		} else {
 			/* Else slow start did not finish, cwnd is non-sense,
 			   ssthresh may be also invalid.
 			 */
 			if (!dst_metric_locked(dst, RTAX_CWND))
-				dst->metrics[RTAX_CWND-1] = (dst->metrics[RTAX_CWND-1] + tp->snd_ssthresh) >> 1;
-			if (dst->metrics[RTAX_SSTHRESH-1] &&
+				dst->metrics[RTAX_CWND-1] = (dst_metric(dst, RTAX_CWND) + tp->snd_ssthresh) >> 1;
+			if (dst_metric(dst, RTAX_SSTHRESH) &&
 			    !dst_metric_locked(dst, RTAX_SSTHRESH) &&
-			    tp->snd_ssthresh > dst->metrics[RTAX_SSTHRESH-1])
+			    tp->snd_ssthresh > dst_metric(dst, RTAX_SSTHRESH))
 				dst->metrics[RTAX_SSTHRESH-1] = tp->snd_ssthresh;
 		}
 
 		if (!dst_metric_locked(dst, RTAX_REORDERING)) {
-			if (dst->metrics[RTAX_REORDERING-1] < tp->reordering &&
+			if (dst_metric(dst, RTAX_REORDERING) < tp->reordering &&
 			    tp->reordering != sysctl_tcp_reordering)
 				dst->metrics[RTAX_REORDERING-1] = tp->reordering;
 		}