net/tls: Read sk_prot once when building tls proto ops

Apart from being a "tremendous" win when it comes to generated machine
code (see bloat-o-meter output for x86-64 below) this mainly prepares
ground for annotating access to sk_prot with READ_ONCE, so that we don't
pepper the code with access annotations and needlessly repeat loads.

add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-46 (-46)
Function                                     old     new   delta
tls_init                                     851     805     -46
Total: Before=21063, After=21017, chg -0.22%

Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
index ff08b2ff75979d8c71da3cfac373f16643533fdc..e7de0306a7dfd52979c67c77999844a44263fda2 100644 (file)
--- a/net/tls/tls_main.c
+++ b/net/tls/tls_main.c
@@ -628,24 +628,25 @@ struct tls_context *tls_ctx_create(struct sock *sk)
 static void tls_build_proto(struct sock *sk)
 {
        int ip_ver = sk->sk_family == AF_INET6 ? TLSV6 : TLSV4;
+       const struct proto *prot = sk->sk_prot;
 
        /* Build IPv6 TLS whenever the address of tcpv6 _prot changes */
        if (ip_ver == TLSV6 &&
-           unlikely(sk->sk_prot != smp_load_acquire(&saved_tcpv6_prot))) {
+           unlikely(prot != smp_load_acquire(&saved_tcpv6_prot))) {
                mutex_lock(&tcpv6_prot_mutex);
-               if (likely(sk->sk_prot != saved_tcpv6_prot)) {
-                       build_protos(tls_prots[TLSV6], sk->sk_prot);
-                       smp_store_release(&saved_tcpv6_prot, sk->sk_prot);
+               if (likely(prot != saved_tcpv6_prot)) {
+                       build_protos(tls_prots[TLSV6], prot);
+                       smp_store_release(&saved_tcpv6_prot, prot);
                }
                mutex_unlock(&tcpv6_prot_mutex);
        }
 
        if (ip_ver == TLSV4 &&
-           unlikely(sk->sk_prot != smp_load_acquire(&saved_tcpv4_prot))) {
+           unlikely(prot != smp_load_acquire(&saved_tcpv4_prot))) {
                mutex_lock(&tcpv4_prot_mutex);
-               if (likely(sk->sk_prot != saved_tcpv4_prot)) {
-                       build_protos(tls_prots[TLSV4], sk->sk_prot);
-                       smp_store_release(&saved_tcpv4_prot, sk->sk_prot);
+               if (likely(prot != saved_tcpv4_prot)) {
+                       build_protos(tls_prots[TLSV4], prot);
+                       smp_store_release(&saved_tcpv4_prot, prot);
                }
                mutex_unlock(&tcpv4_prot_mutex);
        }