ipv4: remove fib_info_lock

After the prior patch, fib_info_lock became redundant
because all of its users are holding RTNL.

BH protection is not needed.

Remove the READ_ONCE()/WRITE_ONCE() annotations around fib_info_cnt,
since it is protected by RTNL.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20241004134720.579244-4-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index e0ffb4ffd95d0f9ebc796c3129bc2f494fb478dd..ece779bfb8f6bec67eb7751761df9a4f158020a8 100644 (file)
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -50,7 +50,6 @@
 
 #include "fib_lookup.h"
 
-static DEFINE_SPINLOCK(fib_info_lock);
 static struct hlist_head *fib_info_hash;
 static struct hlist_head *fib_info_laddrhash;
 static unsigned int fib_info_hash_size;
@@ -260,12 +259,11 @@ EXPORT_SYMBOL_GPL(free_fib_info);
 
 void fib_release_info(struct fib_info *fi)
 {
-       spin_lock_bh(&fib_info_lock);
+       ASSERT_RTNL();
        if (fi && refcount_dec_and_test(&fi->fib_treeref)) {
                hlist_del(&fi->fib_hash);
 
-               /* Paired with READ_ONCE() in fib_create_info(). */
-               WRITE_ONCE(fib_info_cnt, fib_info_cnt - 1);
+               fib_info_cnt--;
 
                if (fi->fib_prefsrc)
                        hlist_del(&fi->fib_lhash);
@@ -282,7 +280,6 @@ void fib_release_info(struct fib_info *fi)
                WRITE_ONCE(fi->fib_dead, 1);
                fib_info_put(fi);
        }
-       spin_unlock_bh(&fib_info_lock);
 }
 
 static inline int nh_comp(struct fib_info *fi, struct fib_info *ofi)
@@ -1266,7 +1263,7 @@ static void fib_info_hash_move(struct hlist_head *new_info_hash,
        unsigned int old_size = fib_info_hash_size;
        unsigned int i;
 
-       spin_lock_bh(&fib_info_lock);
+       ASSERT_RTNL();
        old_info_hash = fib_info_hash;
        old_laddrhash = fib_info_laddrhash;
        fib_info_hash_size = new_size;
@@ -1303,8 +1300,6 @@ static void fib_info_hash_move(struct hlist_head *new_info_hash,
                }
        }
 
-       spin_unlock_bh(&fib_info_lock);
-
        kvfree(old_info_hash);
        kvfree(old_laddrhash);
 }
@@ -1380,6 +1375,7 @@ struct fib_info *fib_create_info(struct fib_config *cfg,
        int nhs = 1;
        struct net *net = cfg->fc_nlinfo.nl_net;
 
+       ASSERT_RTNL();
        if (cfg->fc_type > RTN_MAX)
                goto err_inval;
 
@@ -1422,8 +1418,7 @@ struct fib_info *fib_create_info(struct fib_config *cfg,
 
        err = -ENOBUFS;
 
-       /* Paired with WRITE_ONCE() in fib_release_info() */
-       if (READ_ONCE(fib_info_cnt) >= fib_info_hash_size) {
+       if (fib_info_cnt >= fib_info_hash_size) {
                unsigned int new_size = fib_info_hash_size << 1;
                struct hlist_head *new_info_hash;
                struct hlist_head *new_laddrhash;
@@ -1582,7 +1577,7 @@ link_it:
 
        refcount_set(&fi->fib_treeref, 1);
        refcount_set(&fi->fib_clntref, 1);
-       spin_lock_bh(&fib_info_lock);
+
        fib_info_cnt++;
        hlist_add_head(&fi->fib_hash,
                       &fib_info_hash[fib_info_hashfn(fi)]);
@@ -1604,7 +1599,6 @@ link_it:
                        hlist_add_head_rcu(&nexthop_nh->nh_hash, head);
                } endfor_nexthops(fi)
        }
-       spin_unlock_bh(&fib_info_lock);
        return fi;
 
 err_inval: