[PATCH mptcp-next v6 1/4] mptcp: sockopt: factor inet_flags propagation into a mask

[David Carlier <devnexen@gmail.com>]

Introduce MPTCP_INET_FLAGS_MASK and replace the per-flag
inet_assign_bit() calls in sync_socket_options() with a loop driven
by the mask that calls assign_bit() per set bit, preserving the
per-bit atomicity of the original. Further flags propagated by MPTCP
can be added by extending the mask rather than touching the call
site.

No functional change.

Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David Carlier <devnexen@gmail.com>
---
 net/mptcp/sockopt.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
index 1cf608e7357b..20c737b2e704 100644
--- a/net/mptcp/sockopt.c
+++ b/net/mptcp/sockopt.c
@@ -16,6 +16,10 @@
 
 #define MIN_INFO_OPTLEN_SIZE		16
 #define MIN_FULL_INFO_OPTLEN_SIZE	40
+#define MPTCP_INET_FLAGS_MASK \
+	(BIT(INET_FLAGS_TRANSPARENT) | \
+	 BIT(INET_FLAGS_FREEBIND) | \
+	 BIT(INET_FLAGS_BIND_ADDRESS_NO_PORT))
 
 static struct sock *__mptcp_tcp_fallback(struct mptcp_sock *msk)
 {
@@ -1540,6 +1544,9 @@ static void sync_socket_options(struct mptcp_sock *msk, struct sock *ssk)
 {
 	static const unsigned int tx_rx_locks = SOCK_RCVBUF_LOCK | SOCK_SNDBUF_LOCK;
 	struct sock *sk = (struct sock *)msk;
+	unsigned long mask = MPTCP_INET_FLAGS_MASK;
+	unsigned long src;
+	int b;
 	bool keep_open;
 
 	keep_open = sock_flag(sk, SOCK_KEEPOPEN);
@@ -1586,9 +1593,11 @@ static void sync_socket_options(struct mptcp_sock *msk, struct sock *ssk)
 	tcp_sock_set_keepcnt(ssk, msk->keepalive_cnt);
 	tcp_sock_set_maxseg(ssk, msk->maxseg);
 
-	inet_assign_bit(TRANSPARENT, ssk, inet_test_bit(TRANSPARENT, sk));
-	inet_assign_bit(FREEBIND, ssk, inet_test_bit(FREEBIND, sk));
-	inet_assign_bit(BIND_ADDRESS_NO_PORT, ssk, inet_test_bit(BIND_ADDRESS_NO_PORT, sk));
+	src = READ_ONCE(inet_sk(sk)->inet_flags);
+
+	for_each_set_bit(b, &mask, BITS_PER_LONG)
+		assign_bit(b, &inet_sk(ssk)->inet_flags, src & BIT(b));
+
 	WRITE_ONCE(inet_sk(ssk)->local_port_range, READ_ONCE(inet_sk(sk)->local_port_range));
 }
 
-- 
2.53.0