mptcp: avoid atomic bit manipulation when possible

Currently the msk->flags bitmask carries both state for the
mptcp_release_cb() - mostly touched under the mptcp data lock
- and others state info touched even outside such lock scope.

As a consequence, msk->flags is always manipulated with
atomic operations.

This change splits such bitmask in two separate fields, so
that we use plain bit operations when touching the
cb-related info.

The MPTCP_PUSH_PENDING bit needs additional care, as it is the
only CB related field currently accessed either under the mptcp
data lock or the mptcp socket lock.
Let's add another mask just for such bit's sake.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 11 insertions, 7 deletions

diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 962f3b6b6a1d..a77f512d5ad7 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -110,18 +110,20 @@
 /* MPTCP TCPRST flags */
 #define MPTCP_RST_TRANSIENT	BIT(0)
 
-/* MPTCP socket flags */
+/* MPTCP socket atomic flags */
 #define MPTCP_NOSPACE		1
 #define MPTCP_WORK_RTX		2
 #define MPTCP_WORK_EOF		3
 #define MPTCP_FALLBACK_DONE	4
 #define MPTCP_WORK_CLOSE_SUBFLOW 5
-#define MPTCP_PUSH_PENDING	6
-#define MPTCP_CLEAN_UNA		7
-#define MPTCP_ERROR_REPORT	8
-#define MPTCP_RETRANSMIT	9
-#define MPTCP_FLUSH_JOIN_LIST	10
-#define MPTCP_CONNECTED		11
+
+/* MPTCP socket release cb flags */
+#define MPTCP_PUSH_PENDING	1
+#define MPTCP_CLEAN_UNA		2
+#define MPTCP_ERROR_REPORT	3
+#define MPTCP_RETRANSMIT	4
+#define MPTCP_FLUSH_JOIN_LIST	5
+#define MPTCP_CONNECTED		6
 
 static inline bool before64(__u64 seq1, __u64 seq2)
 {
@@ -250,6 +252,8 @@ struct mptcp_sock {
 	u32		token;
 	int		rmem_released;
 	unsigned long	flags;
+	unsigned long	cb_flags;
+	unsigned long	push_pending;
 	bool		recovery;		/* closing subflow write queue reinjected */
 	bool		can_ack;
 	bool		fully_established;