ipv6: avoid high order memory allocations for /proc/net/ipv6_route

Dumping routes on a system with lots rt6_infos in the fibs causes up to
11-order allocations in seq_file (which fail). While we could switch
there to vmalloc we could just implement the streaming interface for
/proc/net/ipv6_route. This patch switches /proc/net/ipv6_route from
single_open_net to seq_open_net.

loff_t *pos tracks dst entries.

Also kill never used struct rt6_proc_arg and now unused function
fib6_clean_all_ro.

Cc: Ben Greear <greearb@candelatech.com>
Cc: Patrick McHardy <kaber@trash.net>
Cc: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index eab88f0..6738f34 100644 (file)
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -280,10 +280,6 @@ struct fib6_node *fib6_locate(struct fib6_node *root,
                              const struct in6_addr *daddr, int dst_len,
                              const struct in6_addr *saddr, int src_len);
 
-void fib6_clean_all_ro(struct net *net,
-                      int (*func)(struct rt6_info *, void *arg),
-                      int prune, void *arg);
-
 void fib6_clean_all(struct net *net, int (*func)(struct rt6_info *, void *arg),
                    int prune, void *arg);
 
@@ -299,6 +295,8 @@ void fib6_gc_cleanup(void);
 
 int fib6_init(void);
 
+int ipv6_route_open(struct inode *inode, struct file *file);
+
 #ifdef CONFIG_IPV6_MULTIPLE_TABLES
 int fib6_rules_init(void);
 void fib6_rules_cleanup(void);

diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 5bec666..05ffa54 100644 (file)
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -1529,25 +1529,6 @@ static void fib6_clean_tree(struct net *net, struct fib6_node *root,
        fib6_walk(&c.w);
 }
 
-void fib6_clean_all_ro(struct net *net, int (*func)(struct rt6_info *, void *arg),
-                   int prune, void *arg)
-{
-       struct fib6_table *table;
-       struct hlist_head *head;
-       unsigned int h;
-
-       rcu_read_lock();
-       for (h = 0; h < FIB6_TABLE_HASHSZ; h++) {
-               head = &net->ipv6.fib_table_hash[h];
-               hlist_for_each_entry_rcu(table, head, tb6_hlist) {
-                       read_lock_bh(&table->tb6_lock);
-                       fib6_clean_tree(net, &table->tb6_root,
-                                       func, prune, arg);
-                       read_unlock_bh(&table->tb6_lock);
-               }
-       }
-       rcu_read_unlock();
-}
 void fib6_clean_all(struct net *net, int (*func)(struct rt6_info *, void *arg),
                    int prune, void *arg)
 {
@@ -1782,3 +1763,175 @@ void fib6_gc_cleanup(void)
        unregister_pernet_subsys(&fib6_net_ops);
        kmem_cache_destroy(fib6_node_kmem);
 }
+
+#ifdef CONFIG_PROC_FS
+
+struct ipv6_route_iter {
+       struct seq_net_private p;
+       struct fib6_walker_t w;
+       loff_t skip;
+       struct fib6_table *tbl;
+};
+
+static int ipv6_route_seq_show(struct seq_file *seq, void *v)
+{
+       struct rt6_info *rt = v;
+       struct ipv6_route_iter *iter = seq->private;
+
+       seq_printf(seq, "%pi6 %02x ", &rt->rt6i_dst.addr, rt->rt6i_dst.plen);
+
+#ifdef CONFIG_IPV6_SUBTREES
+       seq_printf(seq, "%pi6 %02x ", &rt->rt6i_src.addr, rt->rt6i_src.plen);
+#else
+       seq_puts(seq, "00000000000000000000000000000000 00 ");
+#endif
+       if (rt->rt6i_flags & RTF_GATEWAY)
+               seq_printf(seq, "%pi6", &rt->rt6i_gateway);
+       else
+               seq_puts(seq, "00000000000000000000000000000000");
+
+       seq_printf(seq, " %08x %08x %08x %08x %8s\n",
+                  rt->rt6i_metric, atomic_read(&rt->dst.__refcnt),
+                  rt->dst.__use, rt->rt6i_flags,
+                  rt->dst.dev ? rt->dst.dev->name : "");
+       iter->w.leaf = NULL;
+       return 0;
+}
+
+static int ipv6_route_yield(struct fib6_walker_t *w)
+{
+       struct ipv6_route_iter *iter = w->args;
+
+       if (!iter->skip)
+               return 1;
+
+       do {
+               iter->w.leaf = iter->w.leaf->dst.rt6_next;
+               iter->skip--;
+               if (!iter->skip && iter->w.leaf)
+                       return 1;
+       } while (iter->w.leaf);
+
+       return 0;
+}
+
+static void ipv6_route_seq_setup_walk(struct ipv6_route_iter *iter)
+{
+       memset(&iter->w, 0, sizeof(iter->w));
+       iter->w.func = ipv6_route_yield;
+       iter->w.root = &iter->tbl->tb6_root;
+       iter->w.state = FWS_INIT;
+       iter->w.node = iter->w.root;
+       iter->w.args = iter;
+       INIT_LIST_HEAD(&iter->w.lh);
+       fib6_walker_link(&iter->w);
+}
+
+static struct fib6_table *ipv6_route_seq_next_table(struct fib6_table *tbl,
+                                                   struct net *net)
+{
+       unsigned int h;
+       struct hlist_node *node;
+
+       if (tbl) {
+               h = (tbl->tb6_id & (FIB6_TABLE_HASHSZ - 1)) + 1;
+               node = rcu_dereference_bh(hlist_next_rcu(&tbl->tb6_hlist));
+       } else {
+               h = 0;
+               node = NULL;
+       }
+
+       while (!node && h < FIB6_TABLE_HASHSZ) {
+               node = rcu_dereference_bh(
+                       hlist_first_rcu(&net->ipv6.fib_table_hash[h++]));
+       }
+       return hlist_entry_safe(node, struct fib6_table, tb6_hlist);
+}
+
+static void *ipv6_route_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+       int r;
+       struct rt6_info *n;
+       struct net *net = seq_file_net(seq);
+       struct ipv6_route_iter *iter = seq->private;
+
+       if (!v)
+               goto iter_table;
+
+       n = ((struct rt6_info *)v)->dst.rt6_next;
+       if (n) {
+               ++*pos;
+               return n;
+       }
+
+iter_table:
+       read_lock(&iter->tbl->tb6_lock);
+       r = fib6_walk_continue(&iter->w);
+       read_unlock(&iter->tbl->tb6_lock);
+       if (r > 0) {
+               if (v)
+                       ++*pos;
+               return iter->w.leaf;
+       } else if (r < 0) {
+               fib6_walker_unlink(&iter->w);
+               return NULL;
+       }
+       fib6_walker_unlink(&iter->w);
+
+       iter->tbl = ipv6_route_seq_next_table(iter->tbl, net);
+       if (!iter->tbl)
+               return NULL;
+
+       ipv6_route_seq_setup_walk(iter);
+       goto iter_table;
+}
+
+static void *ipv6_route_seq_start(struct seq_file *seq, loff_t *pos)
+       __acquires(RCU_BH)
+{
+       struct net *net = seq_file_net(seq);
+       struct ipv6_route_iter *iter = seq->private;
+
+       rcu_read_lock_bh();
+       iter->tbl = ipv6_route_seq_next_table(NULL, net);
+       iter->skip = *pos;
+
+       if (iter->tbl) {
+               ipv6_route_seq_setup_walk(iter);
+               return ipv6_route_seq_next(seq, NULL, pos);
+       } else {
+               return NULL;
+       }
+}
+
+static bool ipv6_route_iter_active(struct ipv6_route_iter *iter)
+{
+       struct fib6_walker_t *w = &iter->w;
+       return w->node && !(w->state == FWS_U && w->node == w->root);
+}
+
+static void ipv6_route_seq_stop(struct seq_file *seq, void *v)
+       __releases(RCU_BH)
+{
+       struct ipv6_route_iter *iter = seq->private;
+
+       if (ipv6_route_iter_active(iter))
+               fib6_walker_unlink(&iter->w);
+
+       rcu_read_unlock_bh();
+}
+
+static const struct seq_operations ipv6_route_seq_ops = {
+       .start  = ipv6_route_seq_start,
+       .next   = ipv6_route_seq_next,
+       .stop   = ipv6_route_seq_stop,
+       .show   = ipv6_route_seq_show
+};
+
+int ipv6_route_open(struct inode *inode, struct file *file)
+{
+       return seq_open_net(inode, file, &ipv6_route_seq_ops,
+                           sizeof(struct ipv6_route_iter));
+}
+
+#endif /* CONFIG_PROC_FS */

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index c979dd9..aa901bb 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2800,56 +2800,12 @@ static int ip6_route_dev_notify(struct notifier_block *this,
 
 #ifdef CONFIG_PROC_FS
 
-struct rt6_proc_arg
-{
-       char *buffer;
-       int offset;
-       int length;
-       int skip;
-       int len;
-};
-
-static int rt6_info_route(struct rt6_info *rt, void *p_arg)
-{
-       struct seq_file *m = p_arg;
-
-       seq_printf(m, "%pi6 %02x ", &rt->rt6i_dst.addr, rt->rt6i_dst.plen);
-
-#ifdef CONFIG_IPV6_SUBTREES
-       seq_printf(m, "%pi6 %02x ", &rt->rt6i_src.addr, rt->rt6i_src.plen);
-#else
-       seq_puts(m, "00000000000000000000000000000000 00 ");
-#endif
-       if (rt->rt6i_flags & RTF_GATEWAY) {
-               seq_printf(m, "%pi6", &rt->rt6i_gateway);
-       } else {
-               seq_puts(m, "00000000000000000000000000000000");
-       }
-       seq_printf(m, " %08x %08x %08x %08x %8s\n",
-                  rt->rt6i_metric, atomic_read(&rt->dst.__refcnt),
-                  rt->dst.__use, rt->rt6i_flags,
-                  rt->dst.dev ? rt->dst.dev->name : "");
-       return 0;
-}
-
-static int ipv6_route_show(struct seq_file *m, void *v)
-{
-       struct net *net = (struct net *)m->private;
-       fib6_clean_all_ro(net, rt6_info_route, 0, m);
-       return 0;
-}
-
-static int ipv6_route_open(struct inode *inode, struct file *file)
-{
-       return single_open_net(inode, file, ipv6_route_show);
-}
-
 static const struct file_operations ipv6_route_proc_fops = {
        .owner          = THIS_MODULE,
        .open           = ipv6_route_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
-       .release        = single_release_net,
+       .release        = seq_release_net,
 };
 
 static int rt6_stats_seq_show(struct seq_file *seq, void *v)