net: avoid an indirect call in ____sys_recvmsg()

CONFIG_RETPOLINE=y made indirect calls expensive.

gcc seems to add an indirect call in ____sys_recvmsg().

Rewriting the code slightly makes sure to avoid this indirection.

Alternative would be to not call sock_recvmsg() and instead
use security_socket_recvmsg() and sock_recvmsg_nosec(),
but this is less readable IMO.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: David Laight <David.Laight@aculab.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/socket.c b/net/socket.c
index ea28cbb9e2e7a7180ee63de2d09a81aacb001ab7..5af84d71cbc2f731def460b70aa7f68533a90b16 100644 (file)
--- a/net/socket.c
+++ b/net/socket.c
@@ -2559,7 +2559,12 @@ static int ____sys_recvmsg(struct socket *sock, struct msghdr *msg_sys,
 
        if (sock->file->f_flags & O_NONBLOCK)
                flags |= MSG_DONTWAIT;
-       err = (nosec ? sock_recvmsg_nosec : sock_recvmsg)(sock, msg_sys, flags);
+
+       if (unlikely(nosec))
+               err = sock_recvmsg_nosec(sock, msg_sys, flags);
+       else
+               err = sock_recvmsg(sock, msg_sys, flags);
+
        if (err < 0)
                goto out;
        len = err;