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

[Satoru SATOH <satoru.satoh@gmail.com>]

# I'm very sorry, again. My patch was wrongly formatted by my mailer. Resend it.

YOSHIFUJI Hideaki / 吉藤英明 wrote:
> Sato-san, I think we have more places, e.g., in net/ipv4/route.c:
>     if (rt->u.dst.metrics[RTAX_HOPLIMIT-1] == 0)
> should be converted as
>     if (dst_metric(&rt->u.dst, RTAX_HOPLIMIT) == 0)
>
> Could you annotate those as well, please?
>
> Maybe we could introduce dst_metric_set(), but it is a
> different issue.
>
> --yoshfuji
Right. Here is a updated version.

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>

 net/decnet/dn_route.c |   12 ++++++------
 net/ipv4/route.c      |   16 ++++++++--------
 net/ipv4/tcp_input.c  |   15 ++++++++-------
 net/ipv6/route.c      |    6 +++---
 4 files changed, 25 insertions(+), 24 deletions(-)

diff --git a/net/decnet/dn_route.c b/net/decnet/dn_route.c
index 2f665a5..f50e88b 100644
--- a/net/decnet/dn_route.c
+++ b/net/decnet/dn_route.c
@@ -235,14 +235,14 @@ static void dn_dst_update_pmtu(struct dst_entry *dst, u32 mtu)
 	else
 		min_mtu -= 21;

-	if (dst->metrics[RTAX_MTU-1] > mtu && mtu >= min_mtu) {
+	if (dst_metric(dst, RTAX_MTU) > mtu && mtu >= min_mtu) {
 		if (!(dst_metric_locked(dst, RTAX_MTU))) {
 			dst->metrics[RTAX_MTU-1] = mtu;
 			dst_set_expires(dst, dn_rt_mtu_expires);
 		}
 		if (!(dst_metric_locked(dst, RTAX_ADVMSS))) {
 			u32 mss = mtu - DN_MAX_NSP_DATA_HEADER;
-			if (dst->metrics[RTAX_ADVMSS-1] > mss)
+			if (dst_metric(dst, RTAX_ADVMSS) > mss)
 				dst->metrics[RTAX_ADVMSS-1] = mss;
 		}
 	}
@@ -805,12 +805,12 @@ static int dn_rt_set_next_hop(struct dn_route *rt, struct dn_fib_res *res)
 		rt->u.dst.neighbour = n;
 	}

-	if (rt->u.dst.metrics[RTAX_MTU-1] == 0 ||
-	    rt->u.dst.metrics[RTAX_MTU-1] > rt->u.dst.dev->mtu)
+	if (dst_metric(&rt->u.dst, RTAX_MTU) == 0 ||
+	    dst_metric(&rt->u.dst, RTAX_MTU) > rt->u.dst.dev->mtu)
 		rt->u.dst.metrics[RTAX_MTU-1] = rt->u.dst.dev->mtu;
 	mss = dn_mss_from_pmtu(dev, dst_mtu(&rt->u.dst));
-	if (rt->u.dst.metrics[RTAX_ADVMSS-1] == 0 ||
-	    rt->u.dst.metrics[RTAX_ADVMSS-1] > mss)
+	if (dst_metric(&rt->u.dst, RTAX_ADVMSS) == 0 ||
+	    dst_metric(&rt->u.dst, RTAX_ADVMSS) > mss)
 		rt->u.dst.metrics[RTAX_ADVMSS-1] = mss;
 	return 0;
 }
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index ce25a13..24dc66b 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1462,14 +1462,14 @@ unsigned short ip_rt_frag_needed(struct net *net, struct iphdr *iph,

 					/* BSD 4.2 compatibility hack :-( */
 					if (mtu == 0 &&
-					    old_mtu >= rth->u.dst.metrics[RTAX_MTU-1] &&
+					    old_mtu >= dst_metric(&rth->u.dst, RTAX_MTU) &&
 					    old_mtu >= 68 + (iph->ihl << 2))
 						old_mtu -= iph->ihl << 2;

 					mtu = guess_mtu(old_mtu);
 				}
-				if (mtu <= rth->u.dst.metrics[RTAX_MTU-1]) {
-					if (mtu < rth->u.dst.metrics[RTAX_MTU-1]) {
+				if (mtu <= dst_metric(&rth->u.dst, RTAX_MTU)) {
+					if (mtu < dst_metric(&rth->u.dst, RTAX_MTU)) {
 						dst_confirm(&rth->u.dst);
 						if (mtu < ip_rt_min_pmtu) {
 							mtu = ip_rt_min_pmtu;
@@ -1491,7 +1491,7 @@ unsigned short ip_rt_frag_needed(struct net *net, struct iphdr *iph,

 static void ip_rt_update_pmtu(struct dst_entry *dst, u32 mtu)
 {
-	if (dst->metrics[RTAX_MTU-1] > mtu && mtu >= 68 &&
+	if (dst_metric(dst, RTAX_MTU) > mtu && mtu >= 68 &&
 	    !(dst_metric_locked(dst, RTAX_MTU))) {
 		if (mtu < ip_rt_min_pmtu) {
 			mtu = ip_rt_min_pmtu;
@@ -1618,14 +1618,14 @@ static void rt_set_nexthop(struct rtable *rt, struct fib_result *res, u32 itag)
 	} else
 		rt->u.dst.metrics[RTAX_MTU-1]= rt->u.dst.dev->mtu;

-	if (rt->u.dst.metrics[RTAX_HOPLIMIT-1] == 0)
+	if (dst_metric(&rt->u.dst, RTAX_HOPLIMIT) == 0)
 		rt->u.dst.metrics[RTAX_HOPLIMIT-1] = sysctl_ip_default_ttl;
-	if (rt->u.dst.metrics[RTAX_MTU-1] > IP_MAX_MTU)
+	if (dst_metric(&rt->u.dst, RTAX_MTU) > IP_MAX_MTU)
 		rt->u.dst.metrics[RTAX_MTU-1] = IP_MAX_MTU;
-	if (rt->u.dst.metrics[RTAX_ADVMSS-1] == 0)
+	if (dst_metric(&rt->u.dst, RTAX_ADVMSS) == 0)
 		rt->u.dst.metrics[RTAX_ADVMSS-1] = max_t(unsigned int, rt->u.dst.dev->mtu - 40,
 				       ip_rt_min_advmss);
-	if (rt->u.dst.metrics[RTAX_ADVMSS-1] > 65535 - 40)
+	if (dst_metric(&rt->u.dst, RTAX_ADVMSS) > 65535 - 40)
 		rt->u.dst.metrics[RTAX_ADVMSS-1] = 65535 - 40;

 #ifdef CONFIG_NET_CLS_ROUTE
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 0298f80..3754055 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 @@ static u32 tcp_rto_min(struct sock *sk)
 	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 @@ void tcp_update_metrics(struct sock *sk)
 				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 @@ void tcp_update_metrics(struct sock *sk)
 				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;
 		}
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index a493ad9..12bba08 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1243,11 +1243,11 @@ install_route:
 		}
 	}

-	if (rt->u.dst.metrics[RTAX_HOPLIMIT-1] == 0)
+	if (dst_metric(&rt->u.dst, RTAX_HOPLIMIT) == 0)
 		rt->u.dst.metrics[RTAX_HOPLIMIT-1] = -1;
-	if (!rt->u.dst.metrics[RTAX_MTU-1])
+	if (!dst_metric(&rt->u.dst, RTAX_MTU))
 		rt->u.dst.metrics[RTAX_MTU-1] = ipv6_get_mtu(dev);
-	if (!rt->u.dst.metrics[RTAX_ADVMSS-1])
+	if (!dst_metric(&rt->u.dst, RTAX_ADVMSS))
 		rt->u.dst.metrics[RTAX_ADVMSS-1] = ipv6_advmss(net, dst_mtu(&rt->u.dst));
 	rt->u.dst.dev = dev;
 	rt->rt6i_idev = idev;