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-rw-r--r--include/net/mptcp.h4
-rw-r--r--net/ipv4/tcp_timer.c1
-rw-r--r--net/mptcp/ctrl.c20
-rw-r--r--net/mptcp/mib.c1
-rw-r--r--net/mptcp/mib.h1
5 files changed, 27 insertions, 0 deletions
diff --git a/include/net/mptcp.h b/include/net/mptcp.h
index 0bc4ab03f487..814b5f2e3ed5 100644
--- a/include/net/mptcp.h
+++ b/include/net/mptcp.h
@@ -223,6 +223,8 @@ static inline __be32 mptcp_reset_option(const struct sk_buff *skb)
return htonl(0u);
}
+
+void mptcp_active_detect_blackhole(struct sock *sk, bool expired);
#else
static inline void mptcp_init(void)
@@ -307,6 +309,8 @@ static inline struct request_sock *mptcp_subflow_reqsk_alloc(const struct reques
}
static inline __be32 mptcp_reset_option(const struct sk_buff *skb) { return htonl(0u); }
+
+static inline void mptcp_active_detect_blackhole(struct sock *sk, bool expired) { }
#endif /* CONFIG_MPTCP */
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 86169127e4d1..79064580c8c0 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -282,6 +282,7 @@ static int tcp_write_timeout(struct sock *sk)
expired = retransmits_timed_out(sk, retry_until,
READ_ONCE(icsk->icsk_user_timeout));
tcp_fastopen_active_detect_blackhole(sk, expired);
+ mptcp_active_detect_blackhole(sk, expired);
if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_RTO_CB_FLAG))
tcp_call_bpf_3arg(sk, BPF_SOCK_OPS_RTO_CB,
diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c
index 99382c317ebb..0b23e3c5e8ff 100644
--- a/net/mptcp/ctrl.c
+++ b/net/mptcp/ctrl.c
@@ -12,6 +12,7 @@
#include <net/netns/generic.h>
#include "protocol.h"
+#include "mib.h"
#define MPTCP_SYSCTL_PATH "net/mptcp"
@@ -277,6 +278,25 @@ static void mptcp_pernet_del_table(struct mptcp_pernet *pernet) {}
#endif /* CONFIG_SYSCTL */
+/* Check the number of retransmissions, and fallback to TCP if needed */
+void mptcp_active_detect_blackhole(struct sock *ssk, bool expired)
+{
+ struct mptcp_subflow_context *subflow;
+ u32 timeouts;
+
+ if (!sk_is_mptcp(ssk))
+ return;
+
+ timeouts = inet_csk(ssk)->icsk_retransmits;
+ subflow = mptcp_subflow_ctx(ssk);
+
+ if (subflow->request_mptcp && ssk->sk_state == TCP_SYN_SENT &&
+ (timeouts == 2 || (timeouts < 2 && expired))) {
+ MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_MPCAPABLEACTIVEDROP);
+ mptcp_subflow_early_fallback(mptcp_sk(subflow->conn), subflow);
+ }
+}
+
static int __net_init mptcp_net_init(struct net *net)
{
struct mptcp_pernet *pernet = mptcp_get_pernet(net);
diff --git a/net/mptcp/mib.c b/net/mptcp/mib.c
index ec0d461cb921..d70a3e2bfad6 100644
--- a/net/mptcp/mib.c
+++ b/net/mptcp/mib.c
@@ -15,6 +15,7 @@ static const struct snmp_mib mptcp_snmp_list[] = {
SNMP_MIB_ITEM("MPCapableACKRX", MPTCP_MIB_MPCAPABLEPASSIVEACK),
SNMP_MIB_ITEM("MPCapableFallbackACK", MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK),
SNMP_MIB_ITEM("MPCapableFallbackSYNACK", MPTCP_MIB_MPCAPABLEACTIVEFALLBACK),
+ SNMP_MIB_ITEM("MPCapableSYNTXDrop", MPTCP_MIB_MPCAPABLEACTIVEDROP),
SNMP_MIB_ITEM("MPFallbackTokenInit", MPTCP_MIB_TOKENFALLBACKINIT),
SNMP_MIB_ITEM("MPTCPRetrans", MPTCP_MIB_RETRANSSEGS),
SNMP_MIB_ITEM("MPJoinNoTokenFound", MPTCP_MIB_JOINNOTOKEN),
diff --git a/net/mptcp/mib.h b/net/mptcp/mib.h
index d68136f93dac..062775700b63 100644
--- a/net/mptcp/mib.h
+++ b/net/mptcp/mib.h
@@ -10,6 +10,7 @@ enum linux_mptcp_mib_field {
MPTCP_MIB_MPCAPABLEPASSIVEACK, /* Received third ACK with MP_CAPABLE */
MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK,/* Server-side fallback during 3-way handshake */
MPTCP_MIB_MPCAPABLEACTIVEFALLBACK, /* Client-side fallback during 3-way handshake */
+ MPTCP_MIB_MPCAPABLEACTIVEDROP, /* Client-side fallback due to a MPC drop */
MPTCP_MIB_TOKENFALLBACKINIT, /* Could not init/allocate token */
MPTCP_MIB_RETRANSSEGS, /* Segments retransmitted at the MPTCP-level */
MPTCP_MIB_JOINNOTOKEN, /* Received MP_JOIN but the token was not found */