ipv4: fib: Add fib_info_hash_grow().

When the number of struct fib_info exceeds the hash table size in
fib_create_info(), we try to allocate a new hash table with the
doubled size.

The allocation is done in fib_create_info(), and if successful, each
struct fib_info is moved to the new hash table by fib_info_hash_move().

Let's integrate the allocation and fib_info_hash_move() as
fib_info_hash_grow() to make the following change cleaner.

While at it, fib_info_hash_grow() is placed near other hash-table-specific
functions.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20250228042328.96624-8-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 9dc09e80b92beeb16f25a484c015aaf54e55dbae..0cd40ff18d8be3b679678c3cad02b69946c393f4 100644 (file)
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -376,6 +376,46 @@ static void fib_info_hash_free(struct hlist_head *head)
        kvfree(head);
 }
 
+static void fib_info_hash_grow(void)
+{
+       struct hlist_head *new_info_hash, *old_info_hash;
+       unsigned int old_size = 1 << fib_info_hash_bits;
+       unsigned int i;
+
+       if (fib_info_cnt < old_size)
+               return;
+
+       new_info_hash = fib_info_hash_alloc(fib_info_hash_bits + 1);
+       if (!new_info_hash)
+               return;
+
+       old_info_hash = fib_info_hash;
+       fib_info_hash = new_info_hash;
+       fib_info_hash_bits += 1;
+
+       for (i = 0; i < old_size; i++) {
+               struct hlist_head *head = &old_info_hash[i];
+               struct hlist_node *n;
+               struct fib_info *fi;
+
+               hlist_for_each_entry_safe(fi, n, head, fib_hash)
+                       hlist_add_head(&fi->fib_hash, fib_info_hash_bucket(fi));
+       }
+
+       for (i = 0; i < old_size; i++) {
+               struct hlist_head *lhead = &old_info_hash[old_size + i];
+               struct hlist_node *n;
+               struct fib_info *fi;
+
+               hlist_for_each_entry_safe(fi, n, lhead, fib_lhash)
+                       hlist_add_head(&fi->fib_lhash,
+                                      fib_info_laddrhash_bucket(fi->fib_net,
+                                                                fi->fib_prefsrc));
+       }
+
+       fib_info_hash_free(old_info_hash);
+}
+
 /* no metrics, only nexthop id */
 static struct fib_info *fib_find_info_nh(struct net *net,
                                         const struct fib_config *cfg)
@@ -1254,43 +1294,6 @@ int fib_check_nh(struct net *net, struct fib_nh *nh, u32 table, u8 scope,
        return err;
 }
 
-static void fib_info_hash_move(struct hlist_head *new_info_hash)
-{
-       unsigned int old_size = 1 << fib_info_hash_bits;
-       struct hlist_head *old_info_hash;
-       unsigned int i;
-
-       ASSERT_RTNL();
-       old_info_hash = fib_info_hash;
-       fib_info_hash_bits += 1;
-       fib_info_hash = new_info_hash;
-
-       for (i = 0; i < old_size; i++) {
-               struct hlist_head *head = &old_info_hash[i];
-               struct hlist_node *n;
-               struct fib_info *fi;
-
-               hlist_for_each_entry_safe(fi, n, head, fib_hash)
-                       hlist_add_head(&fi->fib_hash, fib_info_hash_bucket(fi));
-       }
-
-       for (i = 0; i < old_size; i++) {
-               struct hlist_head *lhead = &old_info_hash[old_size + i];
-               struct hlist_node *n;
-               struct fib_info *fi;
-
-               hlist_for_each_entry_safe(fi, n, lhead, fib_lhash) {
-                       struct hlist_head *ldest;
-
-                       ldest = fib_info_laddrhash_bucket(fi->fib_net,
-                                                         fi->fib_prefsrc);
-                       hlist_add_head(&fi->fib_lhash, ldest);
-               }
-       }
-
-       fib_info_hash_free(old_info_hash);
-}
-
 __be32 fib_info_update_nhc_saddr(struct net *net, struct fib_nh_common *nhc,
                                 unsigned char scope)
 {
@@ -1403,13 +1406,7 @@ struct fib_info *fib_create_info(struct fib_config *cfg,
        }
 #endif
 
-       if (fib_info_cnt >= (1 << fib_info_hash_bits)) {
-               struct hlist_head *new_info_hash;
-
-               new_info_hash = fib_info_hash_alloc(fib_info_hash_bits + 1);
-               if (new_info_hash)
-                       fib_info_hash_move(new_info_hash);
-       }
+       fib_info_hash_grow();
 
        fi = kzalloc(struct_size(fi, fib_nh, nhs), GFP_KERNEL);
        if (!fi) {