mptcp: introduce MAPPING_BAD_CSUM

This allow moving a couple of conditional out of the fast path,
making the code more easy to follow and will simplify the next
patch.

Fixes: ae66fb2ba6c3 ("mptcp: Do TCP fallback on early DSS checksum failure")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 50ad19adc0037b18b2ba24b389109af5914f584b..42a7c18a1c2452194a0ae47635ae63881a497d10 100644 (file)
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -843,7 +843,8 @@ enum mapping_status {
        MAPPING_INVALID,
        MAPPING_EMPTY,
        MAPPING_DATA_FIN,
-       MAPPING_DUMMY
+       MAPPING_DUMMY,
+       MAPPING_BAD_CSUM
 };
 
 static void dbg_bad_map(struct mptcp_subflow_context *subflow, u32 ssn)
@@ -958,9 +959,7 @@ static enum mapping_status validate_data_csum(struct sock *ssk, struct sk_buff *
                                 subflow->map_data_csum);
        if (unlikely(csum)) {
                MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DATACSUMERR);
-               if (subflow->mp_join || subflow->valid_csum_seen)
-                       subflow->send_mp_fail = 1;
-               return subflow->mp_join ? MAPPING_INVALID : MAPPING_DUMMY;
+               return MAPPING_BAD_CSUM;
        }
 
        subflow->valid_csum_seen = 1;
@@ -1182,10 +1181,8 @@ static bool subflow_check_data_avail(struct sock *ssk)
 
                status = get_mapping_status(ssk, msk);
                trace_subflow_check_data_avail(status, skb_peek(&ssk->sk_receive_queue));
-               if (unlikely(status == MAPPING_INVALID))
-                       goto fallback;
-
-               if (unlikely(status == MAPPING_DUMMY))
+               if (unlikely(status == MAPPING_INVALID || status == MAPPING_DUMMY ||
+                            status == MAPPING_BAD_CSUM))
                        goto fallback;
 
                if (status != MAPPING_OK)
@@ -1227,7 +1224,10 @@ no_data:
 fallback:
        if (!__mptcp_check_fallback(msk)) {
                /* RFC 8684 section 3.7. */
-               if (subflow->send_mp_fail) {
+               if (status == MAPPING_BAD_CSUM &&
+                   (subflow->mp_join || subflow->valid_csum_seen)) {
+                       subflow->send_mp_fail = 1;
+
                        if (!READ_ONCE(msk->allow_infinite_fallback)) {
                                ssk->sk_err = EBADMSG;
                                tcp_set_state(ssk, TCP_CLOSE);