net: mpls: Convert number of nexthops to u8

Number of nexthops and number of alive nexthops are tracked using an
unsigned int. A route should never have more than 255 nexthops so
convert both to u8. Update all references and intermediate variables
to consistently use u8 as well.

Shrinks the size of mpls_route from 32 bytes to 24 bytes with a 2-byte
hole before the nexthops.

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
index 6bdd2f95b5762d177932b53a9d7f03e213e5ff33..665dec84f001024a64b0d8e12b3021e847327d90 100644 (file)
--- a/net/mpls/af_mpls.c
+++ b/net/mpls/af_mpls.c
@@ -197,10 +197,10 @@ static u32 mpls_multipath_hash(struct mpls_route *rt, struct sk_buff *skb)
 static struct mpls_nh *mpls_select_multipath(struct mpls_route *rt,
                                             struct sk_buff *skb)
 {
-       unsigned int alive;
        u32 hash = 0;
        int nh_index = 0;
        int n = 0;
+       u8 alive;
 
        /* No need to look further into packet if there's only
         * one path
@@ -466,7 +466,7 @@ struct mpls_route_config {
        int                     rc_mp_len;
 };
 
-static struct mpls_route *mpls_rt_alloc(int num_nh, u8 max_alen)
+static struct mpls_route *mpls_rt_alloc(u8 num_nh, u8 max_alen)
 {
        u8 max_alen_aligned = ALIGN(max_alen, VIA_ALEN_ALIGN);
        struct mpls_route *rt;
@@ -744,11 +744,11 @@ errout:
        return err;
 }
 
-static int mpls_count_nexthops(struct rtnexthop *rtnh, int len,
-                              u8 cfg_via_alen, u8 *max_via_alen)
+static u8 mpls_count_nexthops(struct rtnexthop *rtnh, int len,
+                             u8 cfg_via_alen, u8 *max_via_alen)
 {
-       int nhs = 0;
        int remaining = len;
+       u8 nhs = 0;
 
        if (!rtnh) {
                *max_via_alen = cfg_via_alen;
@@ -773,7 +773,13 @@ static int mpls_count_nexthops(struct rtnexthop *rtnh, int len,
                                                      via_alen);
                }
 
+               /* number of nexthops is tracked by a u8.
+                * Check for overflow.
+                */
+               if (nhs == 255)
+                       return 0;
                nhs++;
+
                rtnh = rtnh_next(rtnh, &remaining);
        }
 
@@ -787,8 +793,8 @@ static int mpls_nh_build_multi(struct mpls_route_config *cfg,
        struct rtnexthop *rtnh = cfg->rc_mp;
        struct nlattr *nla_via, *nla_newdst;
        int remaining = cfg->rc_mp_len;
-       int nhs = 0;
        int err = 0;
+       u8 nhs = 0;
 
        change_nexthops(rt) {
                int attrlen;
@@ -842,7 +848,7 @@ static int mpls_route_add(struct mpls_route_config *cfg)
        int err = -EINVAL;
        u8 max_via_alen;
        unsigned index;
-       int nhs;
+       u8 nhs;
 
        index = cfg->rc_label;
 
@@ -1310,7 +1316,7 @@ static void mpls_ifdown(struct net_device *dev, int event)
 {
        struct mpls_route __rcu **platform_label;
        struct net *net = dev_net(dev);
-       unsigned int alive, deleted;
+       u8 alive, deleted;
        unsigned index;
 
        platform_label = rtnl_dereference(net->mpls.platform_label);
@@ -1362,7 +1368,7 @@ static void mpls_ifup(struct net_device *dev, unsigned int flags)
        struct mpls_route __rcu **platform_label;
        struct net *net = dev_net(dev);
        unsigned index;
-       int alive;
+       u8 alive;
 
        platform_label = rtnl_dereference(net->mpls.platform_label);
        for (index = 0; index < net->mpls.platform_labels; index++) {
@@ -1786,8 +1792,8 @@ static int mpls_dump_route(struct sk_buff *skb, u32 portid, u32 seq, int event,
        } else {
                struct rtnexthop *rtnh;
                struct nlattr *mp;
-               int dead = 0;
-               int linkdown = 0;
+               u8 linkdown = 0;
+               u8 dead = 0;
 
                mp = nla_nest_start(skb, RTA_MULTIPATH);
                if (!mp)

diff --git a/net/mpls/internal.h b/net/mpls/internal.h
index 91419fe63464ee97cebfd665914444a115ece304..2ac97433c3b7a7a9a4bef51cc172fbf35664c45b 100644 (file)
--- a/net/mpls/internal.h
+++ b/net/mpls/internal.h
@@ -127,12 +127,13 @@ struct mpls_route { /* next hop label forwarding entry */
        u8                      rt_payload_type;
        u8                      rt_max_alen;
        u8                      rt_ttl_propagate;
-       unsigned int            rt_nhn;
+       u8                      rt_nhn;
 
        /* rt_nhn_alive is accessed under RCU in the packet path; it
         * is modified handling netdev events with rtnl lock held
         */
-       unsigned int            rt_nhn_alive;
+       u8                      rt_nhn_alive;
+       u16                     rt_reserved1;
        struct mpls_nh          rt_nh[0];
 };