ipv4: add __rcu annotations to routes.c

Add __rcu annotations to :
        (struct dst_entry)->rt_next
        (struct rt_hash_bucket)->chain

And use appropriate rcu primitives to reduce sparse warnings if
CONFIG_SPARSE_RCU_POINTER=y

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/dst.h b/include/net/dst.h
index a217c83..ffe9cb7 100644 (file)
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -95,7 +95,7 @@ struct dst_entry {
        unsigned long           lastuse;
        union {
                struct dst_entry *next;
-               struct rtable    *rt_next;
+               struct rtable __rcu *rt_next;
                struct rt6_info   *rt6_next;
                struct dn_route  *dn_next;
        };

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index d6cb2bf..987bf9a 100644 (file)
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -198,7 +198,7 @@ const __u8 ip_tos2prio[16] = {
  */
 
 struct rt_hash_bucket {
-       struct rtable   *chain;
+       struct rtable __rcu     *chain;
 };
 
 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) || \
@@ -280,7 +280,7 @@ static struct rtable *rt_cache_get_first(struct seq_file *seq)
        struct rtable *r = NULL;
 
        for (st->bucket = rt_hash_mask; st->bucket >= 0; --st->bucket) {
-               if (!rt_hash_table[st->bucket].chain)
+               if (!rcu_dereference_raw(rt_hash_table[st->bucket].chain))
                        continue;
                rcu_read_lock_bh();
                r = rcu_dereference_bh(rt_hash_table[st->bucket].chain);
@@ -300,17 +300,17 @@ static struct rtable *__rt_cache_get_next(struct seq_file *seq,
 {
        struct rt_cache_iter_state *st = seq->private;
 
-       r = r->dst.rt_next;
+       r = rcu_dereference_bh(r->dst.rt_next);
        while (!r) {
                rcu_read_unlock_bh();
                do {
                        if (--st->bucket < 0)
                                return NULL;
-               } while (!rt_hash_table[st->bucket].chain);
+               } while (!rcu_dereference_raw(rt_hash_table[st->bucket].chain));
                rcu_read_lock_bh();
-               r = rt_hash_table[st->bucket].chain;
+               r = rcu_dereference_bh(rt_hash_table[st->bucket].chain);
        }
-       return rcu_dereference_bh(r);
+       return r;
 }
 
 static struct rtable *rt_cache_get_next(struct seq_file *seq,
@@ -721,19 +721,23 @@ static void rt_do_flush(int process_context)
        for (i = 0; i <= rt_hash_mask; i++) {
                if (process_context && need_resched())
                        cond_resched();
-               rth = rt_hash_table[i].chain;
+               rth = rcu_dereference_raw(rt_hash_table[i].chain);
                if (!rth)
                        continue;
 
                spin_lock_bh(rt_hash_lock_addr(i));
 #ifdef CONFIG_NET_NS
                {
-               struct rtable ** prev, * p;
+               struct rtable __rcu **prev;
+               struct rtable *p;
 
-               rth = rt_hash_table[i].chain;
+               rth = rcu_dereference_protected(rt_hash_table[i].chain,
+                       lockdep_is_held(rt_hash_lock_addr(i)));
 
                /* defer releasing the head of the list after spin_unlock */
-               for (tail = rth; tail; tail = tail->dst.rt_next)
+               for (tail = rth; tail;
+                    tail = rcu_dereference_protected(tail->dst.rt_next,
+                               lockdep_is_held(rt_hash_lock_addr(i))))
                        if (!rt_is_expired(tail))
                                break;
                if (rth != tail)
@@ -741,8 +745,12 @@ static void rt_do_flush(int process_context)
 
                /* call rt_free on entries after the tail requiring flush */
                prev = &rt_hash_table[i].chain;
-               for (p = *prev; p; p = next) {
-                       next = p->dst.rt_next;
+               for (p = rcu_dereference_protected(*prev,
+                               lockdep_is_held(rt_hash_lock_addr(i)));
+                    p != NULL;
+                    p = next) {
+                       next = rcu_dereference_protected(p->dst.rt_next,
+                               lockdep_is_held(rt_hash_lock_addr(i)));
                        if (!rt_is_expired(p)) {
                                prev = &p->dst.rt_next;
                        } else {
@@ -752,14 +760,15 @@ static void rt_do_flush(int process_context)
                }
                }
 #else
-               rth = rt_hash_table[i].chain;
-               rt_hash_table[i].chain = NULL;
+               rth = rcu_dereference_protected(rt_hash_table[i].chain,
+                       lockdep_is_held(rt_hash_lock_addr(i)));
+               rcu_assign_pointer(rt_hash_table[i].chain, NULL);
                tail = NULL;
 #endif
                spin_unlock_bh(rt_hash_lock_addr(i));
 
                for (; rth != tail; rth = next) {
-                       next = rth->dst.rt_next;
+                       next = rcu_dereference_protected(rth->dst.rt_next, 1);
                        rt_free(rth);
                }
        }
@@ -790,7 +799,7 @@ static int has_noalias(const struct rtable *head, const struct rtable *rth)
        while (aux != rth) {
                if (compare_hash_inputs(&aux->fl, &rth->fl))
                        return 0;
-               aux = aux->dst.rt_next;
+               aux = rcu_dereference_protected(aux->dst.rt_next, 1);
        }
        return ONE;
 }
@@ -799,7 +808,8 @@ static void rt_check_expire(void)
 {
        static unsigned int rover;
        unsigned int i = rover, goal;
-       struct rtable *rth, **rthp;
+       struct rtable *rth;
+       struct rtable __rcu **rthp;
        unsigned long samples = 0;
        unsigned long sum = 0, sum2 = 0;
        unsigned long delta;
@@ -825,11 +835,12 @@ static void rt_check_expire(void)
 
                samples++;
 
-               if (*rthp == NULL)
+               if (rcu_dereference_raw(*rthp) == NULL)
                        continue;
                length = 0;
                spin_lock_bh(rt_hash_lock_addr(i));
-               while ((rth = *rthp) != NULL) {
+               while ((rth = rcu_dereference_protected(*rthp,
+                                       lockdep_is_held(rt_hash_lock_addr(i)))) != NULL) {
                        prefetch(rth->dst.rt_next);
                        if (rt_is_expired(rth)) {
                                *rthp = rth->dst.rt_next;
@@ -941,7 +952,8 @@ static int rt_garbage_collect(struct dst_ops *ops)
        static unsigned long last_gc;
        static int rover;
        static int equilibrium;
-       struct rtable *rth, **rthp;
+       struct rtable *rth;
+       struct rtable __rcu **rthp;
        unsigned long now = jiffies;
        int goal;
        int entries = dst_entries_get_fast(&ipv4_dst_ops);
@@ -995,7 +1007,8 @@ static int rt_garbage_collect(struct dst_ops *ops)
                        k = (k + 1) & rt_hash_mask;
                        rthp = &rt_hash_table[k].chain;
                        spin_lock_bh(rt_hash_lock_addr(k));
-                       while ((rth = *rthp) != NULL) {
+                       while ((rth = rcu_dereference_protected(*rthp,
+                                       lockdep_is_held(rt_hash_lock_addr(k)))) != NULL) {
                                if (!rt_is_expired(rth) &&
                                        !rt_may_expire(rth, tmo, expire)) {
                                        tmo >>= 1;
@@ -1071,7 +1084,7 @@ static int slow_chain_length(const struct rtable *head)
 
        while (rth) {
                length += has_noalias(head, rth);
-               rth = rth->dst.rt_next;
+               rth = rcu_dereference_protected(rth->dst.rt_next, 1);
        }
        return length >> FRACT_BITS;
 }
@@ -1079,9 +1092,9 @@ static int slow_chain_length(const struct rtable *head)
 static int rt_intern_hash(unsigned hash, struct rtable *rt,
                          struct rtable **rp, struct sk_buff *skb, int ifindex)
 {
-       struct rtable   *rth, **rthp;
+       struct rtable   *rth, *cand;
+       struct rtable __rcu **rthp, **candp;
        unsigned long   now;
-       struct rtable *cand, **candp;
        u32             min_score;
        int             chain_length;
        int attempts = !in_softirq();
@@ -1128,7 +1141,8 @@ restart:
        rthp = &rt_hash_table[hash].chain;
 
        spin_lock_bh(rt_hash_lock_addr(hash));
-       while ((rth = *rthp) != NULL) {
+       while ((rth = rcu_dereference_protected(*rthp,
+                       lockdep_is_held(rt_hash_lock_addr(hash)))) != NULL) {
                if (rt_is_expired(rth)) {
                        *rthp = rth->dst.rt_next;
                        rt_free(rth);
@@ -1324,12 +1338,14 @@ EXPORT_SYMBOL(__ip_select_ident);
 
 static void rt_del(unsigned hash, struct rtable *rt)
 {
-       struct rtable **rthp, *aux;
+       struct rtable __rcu **rthp;
+       struct rtable *aux;
 
        rthp = &rt_hash_table[hash].chain;
        spin_lock_bh(rt_hash_lock_addr(hash));
        ip_rt_put(rt);
-       while ((aux = *rthp) != NULL) {
+       while ((aux = rcu_dereference_protected(*rthp,
+                       lockdep_is_held(rt_hash_lock_addr(hash)))) != NULL) {
                if (aux == rt || rt_is_expired(aux)) {
                        *rthp = aux->dst.rt_next;
                        rt_free(aux);
@@ -1346,7 +1362,8 @@ void ip_rt_redirect(__be32 old_gw, __be32 daddr, __be32 new_gw,
 {
        int i, k;
        struct in_device *in_dev = __in_dev_get_rcu(dev);
-       struct rtable *rth, **rthp;
+       struct rtable *rth;
+       struct rtable __rcu **rthp;
        __be32  skeys[2] = { saddr, 0 };
        int  ikeys[2] = { dev->ifindex, 0 };
        struct netevent_redirect netevent;
@@ -1379,7 +1396,7 @@ void ip_rt_redirect(__be32 old_gw, __be32 daddr, __be32 new_gw,
                        unsigned hash = rt_hash(daddr, skeys[i], ikeys[k],
                                                rt_genid(net));
 
-                       rthp=&rt_hash_table[hash].chain;
+                       rthp = &rt_hash_table[hash].chain;
 
                        while ((rth = rcu_dereference(*rthp)) != NULL) {
                                struct rtable *rt;