linux-kernel - [PATCH 3/5] bpf: convert sock map and hash to map_copy

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Date:   Tue, 10 Mar 2020 17:47:09 +0000
From:   Lorenz Bauer <lmb@...udflare.com>
To:     John Fastabend <john.fastabend@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jakub Sitnicki <jakub@...udflare.com>,
        Lorenz Bauer <lmb@...udflare.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>
Cc:     kernel-team@...udflare.com, netdev@...r.kernel.org,
        bpf@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 3/5] bpf: convert sock map and hash to map_copy_value

Migrate sockmap and sockhash to use map_copy_value instead of
map_lookup_elem_sys_only.

Signed-off-by: Lorenz Bauer <lmb@...udflare.com>
---
 net/core/sock_map.c | 48 ++++++++++++++++++++++++++++++---------------
 1 file changed, 32 insertions(+), 16 deletions(-)

diff --git a/net/core/sock_map.c b/net/core/sock_map.c
index a7075b3b4489..03e04426cd21 100644
--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -344,19 +344,34 @@ static void *sock_map_lookup(struct bpf_map *map, void *key)
 	return __sock_map_lookup_elem(map, *(u32 *)key);
 }
 
-static void *sock_map_lookup_sys(struct bpf_map *map, void *key)
+static int __sock_map_copy_value(struct bpf_map *map, struct sock *sk,
+				 void *value)
+{
+	switch (map->value_size) {
+	case sizeof(u64):
+		sock_gen_cookie(sk);
+		*(u64 *)value = atomic64_read(&sk->sk_cookie);
+		return 0;
+
+	default:
+		return -ENOSPC;
+	}
+}
+
+static int sock_map_copy_value(struct bpf_map *map, void *key, void *value)
 {
 	struct sock *sk;
+	int ret = -ENOENT;
 
-	if (map->value_size != sizeof(u64))
-		return ERR_PTR(-ENOSPC);
-
+	rcu_read_lock();
 	sk = __sock_map_lookup_elem(map, *(u32 *)key);
 	if (!sk)
-		return ERR_PTR(-ENOENT);
+		goto out;
 
-	sock_gen_cookie(sk);
-	return &sk->sk_cookie;
+	ret = __sock_map_copy_value(map, sk, value);
+out:
+	rcu_read_unlock();
+	return ret;
 }
 
 static int __sock_map_delete(struct bpf_stab *stab, struct sock *sk_test,
@@ -636,7 +651,7 @@ const struct bpf_map_ops sock_map_ops = {
 	.map_alloc		= sock_map_alloc,
 	.map_free		= sock_map_free,
 	.map_get_next_key	= sock_map_get_next_key,
-	.map_lookup_elem_sys_only = sock_map_lookup_sys,
+	.map_copy_value		= sock_map_copy_value,
 	.map_update_elem	= sock_map_update_elem,
 	.map_delete_elem	= sock_map_delete_elem,
 	.map_lookup_elem	= sock_map_lookup,
@@ -1030,19 +1045,20 @@ static void sock_hash_free(struct bpf_map *map)
 	kfree(htab);
 }
 
-static void *sock_hash_lookup_sys(struct bpf_map *map, void *key)
+static int sock_hash_copy_value(struct bpf_map *map, void *key, void *value)
 {
 	struct sock *sk;
+	int ret = -ENOENT;
 
-	if (map->value_size != sizeof(u64))
-		return ERR_PTR(-ENOSPC);
-
+	rcu_read_lock();
 	sk = __sock_hash_lookup_elem(map, key);
 	if (!sk)
-		return ERR_PTR(-ENOENT);
+		goto out;
 
-	sock_gen_cookie(sk);
-	return &sk->sk_cookie;
+	ret = __sock_map_copy_value(map, sk, value);
+out:
+	rcu_read_unlock();
+	return ret;
 }
 
 static void *sock_hash_lookup(struct bpf_map *map, void *key)
@@ -1139,7 +1155,7 @@ const struct bpf_map_ops sock_hash_ops = {
 	.map_update_elem	= sock_hash_update_elem,
 	.map_delete_elem	= sock_hash_delete_elem,
 	.map_lookup_elem	= sock_hash_lookup,
-	.map_lookup_elem_sys_only = sock_hash_lookup_sys,
+	.map_copy_value		= sock_hash_copy_value,
 	.map_release_uref	= sock_hash_release_progs,
 	.map_check_btf		= map_check_no_btf,
 };
-- 
2.20.1