ipv4: Cache routes in nexthop exception entries.

Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 79 insertions, 64 deletions

diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
index e331746029b4..926142ed8d7a 100644
--- a/include/net/ip_fib.h
+++ b/include/net/ip_fib.h
@@ -55,6 +55,7 @@ struct fib_nh_exception {
         u32                             fnhe_pmtu;
         __be32                          fnhe_gw;
         unsigned long                   fnhe_expires;
+        struct rtable __rcu             *fnhe_rth;
         unsigned long                   fnhe_stamp;
 };
 
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index fe2ca02a1979..da80dc14cc76 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -140,6 +140,21 @@ const struct fib_prop fib_props[RTN_MAX + 1] = {
         },
 };
 
+static void rt_fibinfo_free(struct rtable __rcu **rtp)
+{
+        struct rtable *rt = rcu_dereference_protected(*rtp, 1);
+
+        if (!rt)
+                return;
+
+        /* Not even needed : RCU_INIT_POINTER(*rtp, NULL);
+         * because we waited an RCU grace period before calling
+         * free_fib_info_rcu()
+         */
+
+        dst_free(&rt->dst);
+}
+
 static void free_nh_exceptions(struct fib_nh *nh)
 {
         struct fnhe_hash_bucket *hash = nh->nh_exceptions;
@@ -153,6 +168,9 @@ static void free_nh_exceptions(struct fib_nh *nh)
                         struct fib_nh_exception *next;
                         
                         next = rcu_dereference_protected(fnhe->fnhe_next, 1);
+
+                        rt_fibinfo_free(&fnhe->fnhe_rth);
+
                         kfree(fnhe);
 
                         fnhe = next;
@@ -161,22 +179,7 @@ static void free_nh_exceptions(struct fib_nh *nh)
         kfree(hash);
 }
 
-static void rt_nexthop_free(struct rtable __rcu **rtp)
-{
-        struct rtable *rt = rcu_dereference_protected(*rtp, 1);
-
-        if (!rt)
-                return;
-
-        /* Not even needed : RCU_INIT_POINTER(*rtp, NULL);
-         * because we waited an RCU grace period before calling
-         * free_fib_info_rcu()
-         */
-
-        dst_free(&rt->dst);
-}
-
-static void rt_nexthop_free_cpus(struct rtable __rcu * __percpu *rtp)
+static void rt_fibinfo_free_cpus(struct rtable __rcu * __percpu *rtp)
 {
         int cpu;
 
@@ -203,8 +206,8 @@ static void free_fib_info_rcu(struct rcu_head *head)
                         dev_put(nexthop_nh->nh_dev);
                 if (nexthop_nh->nh_exceptions)
                         free_nh_exceptions(nexthop_nh);
-                rt_nexthop_free_cpus(nexthop_nh->nh_pcpu_rth_output);
-                rt_nexthop_free(&nexthop_nh->nh_rth_input);
+                rt_fibinfo_free_cpus(nexthop_nh->nh_pcpu_rth_output);
+                rt_fibinfo_free(&nexthop_nh->nh_rth_input);
         } endfor_nexthops(fi);
 
         release_net(fi->fib_net);
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 4f6276ce0af3..b102eeb16e34 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -587,11 +587,17 @@ static void ip_rt_build_flow_key(struct flowi4 *fl4, const struct sock *sk,
                 build_sk_flow_key(fl4, sk);
 }
 
-static DEFINE_SEQLOCK(fnhe_seqlock);
+static inline void rt_free(struct rtable *rt)
+{
+        call_rcu(&rt->dst.rcu_head, dst_rcu_free);
+}
+
+static DEFINE_SPINLOCK(fnhe_lock);
 
 static struct fib_nh_exception *fnhe_oldest(struct fnhe_hash_bucket *hash)
 {
         struct fib_nh_exception *fnhe, *oldest;
+        struct rtable *orig;
 
         oldest = rcu_dereference(hash->chain);
         for (fnhe = rcu_dereference(oldest->fnhe_next); fnhe;
@@ -599,6 +605,11 @@ static struct fib_nh_exception *fnhe_oldest(struct fnhe_hash_bucket *hash)
                 if (time_before(fnhe->fnhe_stamp, oldest->fnhe_stamp))
                         oldest = fnhe;
         }
+        orig = rcu_dereference(oldest->fnhe_rth);
+        if (orig) {
+                RCU_INIT_POINTER(oldest->fnhe_rth, NULL);
+                rt_free(orig);
+        }
         return oldest;
 }
 
@@ -620,7 +631,7 @@ static void update_or_create_fnhe(struct fib_nh *nh, __be32 daddr, __be32 gw,
         int depth;
         u32 hval = fnhe_hashfun(daddr);
 
-        write_seqlock_bh(&fnhe_seqlock);
+        spin_lock_bh(&fnhe_lock);
 
         hash = nh->nh_exceptions;
         if (!hash) {
@@ -667,7 +678,7 @@ static void update_or_create_fnhe(struct fib_nh *nh, __be32 daddr, __be32 gw,
         fnhe->fnhe_stamp = jiffies;
 
 out_unlock:
-        write_sequnlock_bh(&fnhe_seqlock);
+        spin_unlock_bh(&fnhe_lock);
         return;
 }
 
@@ -1167,41 +1178,40 @@ static struct fib_nh_exception *find_exception(struct fib_nh *nh, __be32 daddr)
 static void rt_bind_exception(struct rtable *rt, struct fib_nh_exception *fnhe,
                               __be32 daddr)
 {
-        __be32 fnhe_daddr, gw;
-        unsigned long expires;
-        unsigned int seq;
-        u32 pmtu;
-
-restart:
-        seq = read_seqbegin(&fnhe_seqlock);
-        fnhe_daddr = fnhe->fnhe_daddr;
-        gw = fnhe->fnhe_gw;
-        pmtu = fnhe->fnhe_pmtu;
-        expires = fnhe->fnhe_expires;
-        if (read_seqretry(&fnhe_seqlock, seq))
-                goto restart;
-
-        if (daddr != fnhe_daddr)
-                return;
+        spin_lock_bh(&fnhe_lock);
 
-        if (pmtu) {
-                unsigned long diff = expires - jiffies;
+        if (daddr == fnhe->fnhe_daddr) {
+                struct rtable *orig;
 
-                if (time_before(jiffies, expires)) {
-                        rt->rt_pmtu = pmtu;
-                        dst_set_expires(&rt->dst, diff);
+                if (fnhe->fnhe_pmtu) {
+                        unsigned long expires = fnhe->fnhe_expires;
+                        unsigned long diff = expires - jiffies;
+
+                        if (time_before(jiffies, expires)) {
+                                rt->rt_pmtu = fnhe->fnhe_pmtu;
+                                dst_set_expires(&rt->dst, diff);
+                        }
+                }
+                if (fnhe->fnhe_gw) {
+                        rt->rt_flags |= RTCF_REDIRECTED;
+                        rt->rt_gateway = fnhe->fnhe_gw;
                 }
-        }
-        if (gw) {
-                rt->rt_flags |= RTCF_REDIRECTED;
-                rt->rt_gateway = gw;
-        }
-        fnhe->fnhe_stamp = jiffies;
-}
 
-static inline void rt_free(struct rtable *rt)
-{
-        call_rcu(&rt->dst.rcu_head, dst_rcu_free);
+                orig = rcu_dereference(fnhe->fnhe_rth);
+                rcu_assign_pointer(fnhe->fnhe_rth, rt);
+                if (orig)
+                        rt_free(orig);
+
+                fnhe->fnhe_stamp = jiffies;
+        } else {
+                /* Routes we intend to cache in nexthop exception have
+                 * the DST_NOCACHE bit clear.  However, if we are
+                 * unsuccessful at storing this route into the cache
+                 * we really need to set it.
+                 */
+                rt->dst.flags |= DST_NOCACHE;
+        }
+        spin_unlock_bh(&fnhe_lock);
 }
 
 static void rt_cache_route(struct fib_nh *nh, struct rtable *rt)
@@ -1249,13 +1259,13 @@ static void rt_set_nexthop(struct rtable *rt, __be32 daddr,
 
                 if (nh->nh_gw && nh->nh_scope == RT_SCOPE_LINK)
                         rt->rt_gateway = nh->nh_gw;
-                if (unlikely(fnhe))
-                        rt_bind_exception(rt, fnhe, daddr);
                 dst_init_metrics(&rt->dst, fi->fib_metrics, true);
 #ifdef CONFIG_IP_ROUTE_CLASSID
                 rt->dst.tclassid = nh->nh_tclassid;
 #endif
-                if (!(rt->dst.flags & DST_NOCACHE))
+                if (unlikely(fnhe))
+                        rt_bind_exception(rt, fnhe, daddr);
+                else if (!(rt->dst.flags & DST_NOCACHE))
                         rt_cache_route(nh, rt);
         }
 
@@ -1753,22 +1763,23 @@ static struct rtable *__mkroute_output(const struct fib_result *res,
 
         fnhe = NULL;
         if (fi) {
-                fnhe = find_exception(&FIB_RES_NH(*res), fl4->daddr);
-                if (!fnhe && FIB_RES_NH(*res).nh_pcpu_rth_output) {
-                        struct rtable __rcu **prth;
+                struct rtable __rcu **prth;
 
+                fnhe = find_exception(&FIB_RES_NH(*res), fl4->daddr);
+                if (fnhe)
+                        prth = &fnhe->fnhe_rth;
+                else
                         prth = __this_cpu_ptr(FIB_RES_NH(*res).nh_pcpu_rth_output);
-                        rth = rcu_dereference(*prth);
-                        if (rt_cache_valid(rth)) {
-                                dst_hold(&rth->dst);
-                                return rth;
-                        }
+                rth = rcu_dereference(*prth);
+                if (rt_cache_valid(rth)) {
+                        dst_hold(&rth->dst);
+                        return rth;
                 }
         }
         rth = rt_dst_alloc(dev_out,
                            IN_DEV_CONF_GET(in_dev, NOPOLICY),
                            IN_DEV_CONF_GET(in_dev, NOXFRM),
-                           fi && !fnhe);
+                           fi);
         if (!rth)
                 return ERR_PTR(-ENOBUFS);