[PATCH net-next v7 0/7] Implement reset reason mechanism to detect

[PATCH net-next v7 0/7] Implement reset reason mechanism to detect

[Jason Xing]

From: Jason Xing <kernelxing@tencent.com>

In production, there are so many cases about why the RST skb is sent but
we don't have a very convenient/fast method to detect the exact underlying
reasons.

RST is implemented in two kinds: passive kind (like tcp_v4_send_reset())
and active kind (like tcp_send_active_reset()). The former can be traced
carefully 1) in TCP, with the help of drop reasons, which is based on
Eric's idea[1], 2) in MPTCP, with the help of reset options defined in
RFC 8684. The latter is relatively independent, which should be
implemented on our own, such as active reset reasons which can not be
replace by skb drop reason or something like this.

In this series, I focus on the fundamental implement mostly about how
the rstreason mechnism works and give the detailed passive part as an
example, not including the active reset part. In future, we can go
further and refine those NOT_SPECIFIED reasons.

Here are some examples when tracing:
<idle>-0       [002] ..s1.  1830.262425: tcp_send_reset: skbaddr=x
        skaddr=x src=x dest=x state=x reason=NOT_SPECIFIED
<idle>-0       [002] ..s1.  1830.262425: tcp_send_reset: skbaddr=x
        skaddr=x src=x dest=x state=x reason=NO_SOCKET

[1]
Link: https://lore.kernel.org/all/CANn89iJw8x-LqgsWOeJQQvgVg6DnL5aBRLi10QN2WBdr+X4k=w@mail.gmail.com/

v7
Link: https://lore.kernel.org/all/20240417085143.69578-1-kerneljasonxing@gmail.com/
1. get rid of enum casts which could bring potential issues (Eric)
2. use switch-case method to map between reset reason in MPTCP and sk reset
reason (Steven)
3. use switch-case method to map between skb drop reason and sk reset
reason

v6
1. add back casts, or else they are treated as error.

v5
Link: https://lore.kernel.org/all/20240411115630.38420-1-kerneljasonxing@gmail.com/
1. address format issue (like reverse xmas tree) (Eric, Paolo)
2. remove unnecessary casts. (Eric)
3. introduce a helper used in mptcp active reset. See patch 6. (Paolo)

v4
Link: https://lore.kernel.org/all/20240409100934.37725-1-kerneljasonxing@gmail.com/
1. passing 'enum sk_rst_reason' for readability when tracing (Antoine)

v3
Link: https://lore.kernel.org/all/20240404072047.11490-1-kerneljasonxing@gmail.com/
1. rebase (mptcp part) and address what Mat suggested.

v2
Link: https://lore.kernel.org/all/20240403185033.47ebc6a9@kernel.org/
1. rebase against the latest net-next tree


Jason Xing (7):
  net: introduce rstreason to detect why the RST is sent
  rstreason: prepare for passive reset
  rstreason: prepare for active reset
  tcp: support rstreason for passive reset
  mptcp: support rstreason for passive reset
  mptcp: introducing a helper into active reset logic
  rstreason: make it work in trace world

 include/net/request_sock.h |   4 +-
 include/net/rstreason.h    | 144 +++++++++++++++++++++++++++++++++++++
 include/net/tcp.h          |   3 +-
 include/trace/events/tcp.h |  26 +++++--
 net/dccp/ipv4.c            |  10 +--
 net/dccp/ipv6.c            |  10 +--
 net/dccp/minisocks.c       |   3 +-
 net/ipv4/tcp.c             |  15 ++--
 net/ipv4/tcp_ipv4.c        |  15 ++--
 net/ipv4/tcp_minisocks.c   |   3 +-
 net/ipv4/tcp_output.c      |   5 +-
 net/ipv4/tcp_timer.c       |   9 ++-
 net/ipv6/tcp_ipv6.c        |  18 +++--
 net/mptcp/protocol.c       |   2 +-
 net/mptcp/protocol.h       |  11 +++
 net/mptcp/subflow.c        |  27 +++++--
 16 files changed, 258 insertions(+), 47 deletions(-)
 create mode 100644 include/net/rstreason.h

-- 
2.37.3

[PATCH net-next v7 1/7] net: introduce rstreason to detect why the RST is sent

[Jason Xing]

From: Jason Xing <kernelxing@tencent.com>

Add a new standalone file for the easy future extension to support
both active reset and passive reset in the TCP/DCCP/MPTCP protocols.

This patch only does the preparations for reset reason mechanism,
nothing else changes.

The reset reasons are divided into three parts:
1) reuse MP_TCPRST option for MPTCP
2) reuse drop reasons for passive reset in TCP
3) our own reasons which are not relying on other reasons at all

The benefits of a standalone reset reason are listed here:
1) it can cover more than one case, such as reset reasons in MPTCP,
active reset reasons.
2) people can easily/fastly understand and maintain this mechanism.
3) we get unified format of output with prefix stripped.
4) more new reset reasons are on the way
...

I will implement the basic codes of active/passive reset reason in
those three protocols, which are not complete for this moment. For
passive reset part in TCP, I only introduce the NO_SOCKET common case
which could be set as an example.

After this series applied, it will have the ability to open a new
gate to let other people contribute more reasons into it :)

Signed-off-by: Jason Xing <kernelxing@tencent.com>
---
 include/net/rstreason.h | 144 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 144 insertions(+)
 create mode 100644 include/net/rstreason.h

diff --git a/include/net/rstreason.h b/include/net/rstreason.h
new file mode 100644
index 000000000000..c57bc5413c17
--- /dev/null
+++ b/include/net/rstreason.h
@@ -0,0 +1,144 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef _LINUX_RSTREASON_H
+#define _LINUX_RSTREASON_H
+#include <net/dropreason-core.h>
+#include <uapi/linux/mptcp.h>
+
+#define DEFINE_RST_REASON(FN, FNe)	\
+	FN(MPTCP_RST_EUNSPEC)		\
+	FN(MPTCP_RST_EMPTCP)		\
+	FN(MPTCP_RST_ERESOURCE)		\
+	FN(MPTCP_RST_EPROHIBIT)		\
+	FN(MPTCP_RST_EWQ2BIG)		\
+	FN(MPTCP_RST_EBADPERF)		\
+	FN(MPTCP_RST_EMIDDLEBOX)	\
+	FN(NOT_SPECIFIED)		\
+	FN(NO_SOCKET)			\
+	FNe(MAX)
+
+/**
+ * There are three parts in order:
+ * 1) reset reason in MPTCP: only for MPTCP use
+ * 2) skb drop reason: relying on drop reasons for such as passive reset
+ * 3) independent reset reason: such as active reset reasons
+ */
+enum sk_rst_reason {
+	/**
+	 * Copy from include/uapi/linux/mptcp.h.
+	 * These reset fields will not be changed since they adhere to
+	 * RFC 8684. So do not touch them. I'm going to list each definition
+	 * of them respectively.
+	 */
+	/**
+	 * @SK_RST_REASON_MPTCP_RST_EUNSPEC: Unspecified error.
+	 * This is the default error; it implies that the subflow is no
+	 * longer available. The presence of this option shows that the
+	 * RST was generated by an MPTCP-aware device.
+	 */
+	SK_RST_REASON_MPTCP_RST_EUNSPEC,
+	/**
+	 * @SK_RST_REASON_MPTCP_RST_EMPTCP: MPTCP-specific error.
+	 * An error has been detected in the processing of MPTCP options.
+	 * This is the usual reason code to return in the cases where a RST
+	 * is being sent to close a subflow because of an invalid response.
+	 */
+	SK_RST_REASON_MPTCP_RST_EMPTCP,
+	/**
+	 * @SK_RST_REASON_MPTCP_RST_ERESOURCE: Lack of resources.
+	 * This code indicates that the sending host does not have enough
+	 * resources to support the terminated subflow.
+	 */
+	SK_RST_REASON_MPTCP_RST_ERESOURCE,
+	/**
+	 * @SK_RST_REASON_MPTCP_RST_EPROHIBIT: Administratively prohibited.
+	 * This code indicates that the requested subflow is prohibited by
+	 * the policies of the sending host.
+	 */
+	SK_RST_REASON_MPTCP_RST_EPROHIBIT,
+	/**
+	 * @SK_RST_REASON_MPTCP_RST_EWQ2BIG: Too much outstanding data.
+	 * This code indicates that there is an excessive amount of data
+	 * that needs to be transmitted over the terminated subflow while
+	 * having already been acknowledged over one or more other subflows.
+	 * This may occur if a path has been unavailable for a short period
+	 * and it is more efficient to reset and start again than it is to
+	 * retransmit the queued data.
+	 */
+	SK_RST_REASON_MPTCP_RST_EWQ2BIG,
+	/**
+	 * @SK_RST_REASON_MPTCP_RST_EBADPERF: Unacceptable performance.
+	 * This code indicates that the performance of this subflow was
+	 * too low compared to the other subflows of this Multipath TCP
+	 * connection.
+	 */
+	SK_RST_REASON_MPTCP_RST_EBADPERF,
+	/**
+	 * @SK_RST_REASON_MPTCP_RST_EMIDDLEBOX: Middlebox interference.
+	 * Middlebox interference has been detected over this subflow,
+	 * making MPTCP signaling invalid. For example, this may be sent
+	 * if the checksum does not validate.
+	 */
+	SK_RST_REASON_MPTCP_RST_EMIDDLEBOX,
+
+	/**
+	 * Refer to include/net/dropreason-core.h
+	 * Rely on skb drop reason because it indicates exactly why RST
+	 * could happen.
+	 */
+	/** @SK_RST_REASON_NOT_SPECIFIED: reset reason is not specified */
+	SK_RST_REASON_NOT_SPECIFIED,
+	/** @SK_RST_REASON_NO_SOCKET: no valid socket that can be used */
+	SK_RST_REASON_NO_SOCKET,
+
+	/** @SK_RST_REASON_ERROR: unexpected error happens */
+	SK_RST_REASON_ERROR,
+
+	/**
+	 * @SK_RST_REASON_MAX: Maximum of socket reset reasons.
+	 * It shouldn't be used as a real 'reason'.
+	 */
+	SK_RST_REASON_MAX,
+};
+
+/* Convert reset reasons in MPTCP to our own enum type */
+static inline enum sk_rst_reason convert_mptcpreason(u32 reason)
+{
+	switch (reason) {
+	case MPTCP_RST_EUNSPEC:
+		return SK_RST_REASON_MPTCP_RST_EUNSPEC;
+	case MPTCP_RST_EMPTCP:
+		return SK_RST_REASON_MPTCP_RST_EMPTCP;
+	case MPTCP_RST_ERESOURCE:
+		return SK_RST_REASON_MPTCP_RST_ERESOURCE;
+	case MPTCP_RST_EPROHIBIT:
+		return SK_RST_REASON_MPTCP_RST_EPROHIBIT;
+	case MPTCP_RST_EWQ2BIG:
+		return SK_RST_REASON_MPTCP_RST_EWQ2BIG;
+	case MPTCP_RST_EBADPERF:
+		return SK_RST_REASON_MPTCP_RST_EBADPERF;
+	case MPTCP_RST_EMIDDLEBOX:
+		return SK_RST_REASON_MPTCP_RST_EMIDDLEBOX;
+	default:
+		/**
+		 * It should not happen, or else errors may occur
+		 * in MPTCP layer
+		 */
+		return SK_RST_REASON_ERROR;
+	}
+}
+
+/* Convert reset reasons in MPTCP to our own enum type */
+static inline enum sk_rst_reason convert_dropreason(enum skb_drop_reason reason)
+{
+	switch (reason) {
+	case SKB_DROP_REASON_NOT_SPECIFIED:
+		return SK_RST_REASON_NOT_SPECIFIED;
+	case SKB_DROP_REASON_NO_SOCKET:
+		return SK_RST_REASON_NO_SOCKET;
+	default:
+		/* If we don't have our own corresponding reason */
+		return SK_RST_REASON_NOT_SPECIFIED;
+	}
+}
+#endif
-- 
2.37.3

[PATCH net-next v7 2/7] rstreason: prepare for passive reset

[Jason Xing]

From: Jason Xing <kernelxing@tencent.com>

Adjust the parameter and support passing reason of reset which
is for now NOT_SPECIFIED. No functional changes.

Signed-off-by: Jason Xing <kernelxing@tencent.com>
---
 include/net/request_sock.h |  4 +++-
 net/dccp/ipv4.c            | 10 ++++++----
 net/dccp/ipv6.c            | 10 ++++++----
 net/dccp/minisocks.c       |  3 ++-
 net/ipv4/tcp_ipv4.c        | 12 +++++++-----
 net/ipv4/tcp_minisocks.c   |  3 ++-
 net/ipv6/tcp_ipv6.c        | 15 +++++++++------
 net/mptcp/subflow.c        |  8 +++++---
 8 files changed, 40 insertions(+), 25 deletions(-)

diff --git a/include/net/request_sock.h b/include/net/request_sock.h
index 004e651e6067..bdc737832da6 100644
--- a/include/net/request_sock.h
+++ b/include/net/request_sock.h
@@ -18,6 +18,7 @@
 #include <linux/refcount.h>
 
 #include <net/sock.h>
+#include <net/rstreason.h>
 
 struct request_sock;
 struct sk_buff;
@@ -34,7 +35,8 @@ struct request_sock_ops {
 	void		(*send_ack)(const struct sock *sk, struct sk_buff *skb,
 				    struct request_sock *req);
 	void		(*send_reset)(const struct sock *sk,
-				      struct sk_buff *skb);
+				      struct sk_buff *skb,
+				      enum sk_rst_reason reason);
 	void		(*destructor)(struct request_sock *req);
 	void		(*syn_ack_timeout)(const struct request_sock *req);
 };
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index 9fc9cea4c251..ff41bd6f99c3 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -24,6 +24,7 @@
 #include <net/xfrm.h>
 #include <net/secure_seq.h>
 #include <net/netns/generic.h>
+#include <net/rstreason.h>
 
 #include "ackvec.h"
 #include "ccid.h"
@@ -521,7 +522,8 @@ static int dccp_v4_send_response(const struct sock *sk, struct request_sock *req
 	return err;
 }
 
-static void dccp_v4_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb)
+static void dccp_v4_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb,
+				   enum sk_rst_reason reason)
 {
 	int err;
 	const struct iphdr *rxiph;
@@ -706,7 +708,7 @@ int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
 	return 0;
 
 reset:
-	dccp_v4_ctl_send_reset(sk, skb);
+	dccp_v4_ctl_send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
 	kfree_skb(skb);
 	return 0;
 }
@@ -869,7 +871,7 @@ static int dccp_v4_rcv(struct sk_buff *skb)
 		if (nsk == sk) {
 			reqsk_put(req);
 		} else if (dccp_child_process(sk, nsk, skb)) {
-			dccp_v4_ctl_send_reset(sk, skb);
+			dccp_v4_ctl_send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
 			goto discard_and_relse;
 		} else {
 			sock_put(sk);
@@ -909,7 +911,7 @@ static int dccp_v4_rcv(struct sk_buff *skb)
 	if (dh->dccph_type != DCCP_PKT_RESET) {
 		DCCP_SKB_CB(skb)->dccpd_reset_code =
 					DCCP_RESET_CODE_NO_CONNECTION;
-		dccp_v4_ctl_send_reset(sk, skb);
+		dccp_v4_ctl_send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
 	}
 
 discard_it:
diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
index c8ca703dc331..85f4b8fdbe5e 100644
--- a/net/dccp/ipv6.c
+++ b/net/dccp/ipv6.c
@@ -29,6 +29,7 @@
 #include <net/secure_seq.h>
 #include <net/netns/generic.h>
 #include <net/sock.h>
+#include <net/rstreason.h>
 
 #include "dccp.h"
 #include "ipv6.h"
@@ -256,7 +257,8 @@ static void dccp_v6_reqsk_destructor(struct request_sock *req)
 	kfree_skb(inet_rsk(req)->pktopts);
 }
 
-static void dccp_v6_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb)
+static void dccp_v6_ctl_send_reset(const struct sock *sk, struct sk_buff *rxskb,
+				   enum sk_rst_reason reason)
 {
 	const struct ipv6hdr *rxip6h;
 	struct sk_buff *skb;
@@ -656,7 +658,7 @@ static int dccp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
 	return 0;
 
 reset:
-	dccp_v6_ctl_send_reset(sk, skb);
+	dccp_v6_ctl_send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
 discard:
 	if (opt_skb != NULL)
 		__kfree_skb(opt_skb);
@@ -762,7 +764,7 @@ static int dccp_v6_rcv(struct sk_buff *skb)
 		if (nsk == sk) {
 			reqsk_put(req);
 		} else if (dccp_child_process(sk, nsk, skb)) {
-			dccp_v6_ctl_send_reset(sk, skb);
+			dccp_v6_ctl_send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
 			goto discard_and_relse;
 		} else {
 			sock_put(sk);
@@ -801,7 +803,7 @@ static int dccp_v6_rcv(struct sk_buff *skb)
 	if (dh->dccph_type != DCCP_PKT_RESET) {
 		DCCP_SKB_CB(skb)->dccpd_reset_code =
 					DCCP_RESET_CODE_NO_CONNECTION;
-		dccp_v6_ctl_send_reset(sk, skb);
+		dccp_v6_ctl_send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
 	}
 
 discard_it:
diff --git a/net/dccp/minisocks.c b/net/dccp/minisocks.c
index 64d805b27add..251a57cf5822 100644
--- a/net/dccp/minisocks.c
+++ b/net/dccp/minisocks.c
@@ -15,6 +15,7 @@
 #include <net/sock.h>
 #include <net/xfrm.h>
 #include <net/inet_timewait_sock.h>
+#include <net/rstreason.h>
 
 #include "ackvec.h"
 #include "ccid.h"
@@ -202,7 +203,7 @@ struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
 	DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 drop:
 	if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
-		req->rsk_ops->send_reset(sk, skb);
+		req->rsk_ops->send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
 
 	inet_csk_reqsk_queue_drop(sk, req);
 out:
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 88c83ac42129..418d11902fa7 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -70,6 +70,7 @@
 #include <net/xfrm.h>
 #include <net/secure_seq.h>
 #include <net/busy_poll.h>
+#include <net/rstreason.h>
 
 #include <linux/inet.h>
 #include <linux/ipv6.h>
@@ -723,7 +724,8 @@ static bool tcp_v4_ao_sign_reset(const struct sock *sk, struct sk_buff *skb,
  *	Exception: precedence violation. We do not implement it in any case.
  */
 
-static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb)
+static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb,
+			      enum sk_rst_reason reason)
 {
 	const struct tcphdr *th = tcp_hdr(skb);
 	struct {
@@ -1934,7 +1936,7 @@ int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
 	return 0;
 
 reset:
-	tcp_v4_send_reset(rsk, skb);
+	tcp_v4_send_reset(rsk, skb, SK_RST_REASON_NOT_SPECIFIED);
 discard:
 	kfree_skb_reason(skb, reason);
 	/* Be careful here. If this function gets more complicated and
@@ -2276,7 +2278,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
 		} else {
 			drop_reason = tcp_child_process(sk, nsk, skb);
 			if (drop_reason) {
-				tcp_v4_send_reset(nsk, skb);
+				tcp_v4_send_reset(nsk, skb, SK_RST_REASON_NOT_SPECIFIED);
 				goto discard_and_relse;
 			}
 			sock_put(sk);
@@ -2355,7 +2357,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
 bad_packet:
 		__TCP_INC_STATS(net, TCP_MIB_INERRS);
 	} else {
-		tcp_v4_send_reset(NULL, skb);
+		tcp_v4_send_reset(NULL, skb, SK_RST_REASON_NOT_SPECIFIED);
 	}
 
 discard_it:
@@ -2407,7 +2409,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
 		tcp_v4_timewait_ack(sk, skb);
 		break;
 	case TCP_TW_RST:
-		tcp_v4_send_reset(sk, skb);
+		tcp_v4_send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
 		inet_twsk_deschedule_put(inet_twsk(sk));
 		goto discard_it;
 	case TCP_TW_SUCCESS:;
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index f53c7ada2ace..0bc19aca2759 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -22,6 +22,7 @@
 #include <net/tcp.h>
 #include <net/xfrm.h>
 #include <net/busy_poll.h>
+#include <net/rstreason.h>
 
 static bool tcp_in_window(u32 seq, u32 end_seq, u32 s_win, u32 e_win)
 {
@@ -879,7 +880,7 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
 		 * avoid becoming vulnerable to outside attack aiming at
 		 * resetting legit local connections.
 		 */
-		req->rsk_ops->send_reset(sk, skb);
+		req->rsk_ops->send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
 	} else if (fastopen) { /* received a valid RST pkt */
 		reqsk_fastopen_remove(sk, req, true);
 		tcp_reset(sk, skb);
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index bb7c3caf4f85..017f6293b5f4 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -60,6 +60,7 @@
 #include <net/secure_seq.h>
 #include <net/hotdata.h>
 #include <net/busy_poll.h>
+#include <net/rstreason.h>
 
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
@@ -69,7 +70,8 @@
 
 #include <trace/events/tcp.h>
 
-static void	tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb);
+static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb,
+			      enum sk_rst_reason reason);
 static void	tcp_v6_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
 				      struct request_sock *req);
 
@@ -1008,7 +1010,8 @@ static void tcp_v6_send_response(const struct sock *sk, struct sk_buff *skb, u32
 	kfree_skb(buff);
 }
 
-static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
+static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb,
+			      enum sk_rst_reason reason)
 {
 	const struct tcphdr *th = tcp_hdr(skb);
 	struct ipv6hdr *ipv6h = ipv6_hdr(skb);
@@ -1677,7 +1680,7 @@ int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
 	return 0;
 
 reset:
-	tcp_v6_send_reset(sk, skb);
+	tcp_v6_send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
 discard:
 	if (opt_skb)
 		__kfree_skb(opt_skb);
@@ -1862,7 +1865,7 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
 		} else {
 			drop_reason = tcp_child_process(sk, nsk, skb);
 			if (drop_reason) {
-				tcp_v6_send_reset(nsk, skb);
+				tcp_v6_send_reset(nsk, skb, SK_RST_REASON_NOT_SPECIFIED);
 				goto discard_and_relse;
 			}
 			sock_put(sk);
@@ -1939,7 +1942,7 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
 bad_packet:
 		__TCP_INC_STATS(net, TCP_MIB_INERRS);
 	} else {
-		tcp_v6_send_reset(NULL, skb);
+		tcp_v6_send_reset(NULL, skb, SK_RST_REASON_NOT_SPECIFIED);
 	}
 
 discard_it:
@@ -1995,7 +1998,7 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
 		tcp_v6_timewait_ack(sk, skb);
 		break;
 	case TCP_TW_RST:
-		tcp_v6_send_reset(sk, skb);
+		tcp_v6_send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
 		inet_twsk_deschedule_put(inet_twsk(sk));
 		goto discard_it;
 	case TCP_TW_SUCCESS:
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index b94d1dca1094..32fe2ef36d56 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -20,6 +20,8 @@
 #include <net/transp_v6.h>
 #endif
 #include <net/mptcp.h>
+#include <net/rstreason.h>
+
 #include "protocol.h"
 #include "mib.h"
 
@@ -308,7 +310,7 @@ static struct dst_entry *subflow_v4_route_req(const struct sock *sk,
 
 	dst_release(dst);
 	if (!req->syncookie)
-		tcp_request_sock_ops.send_reset(sk, skb);
+		tcp_request_sock_ops.send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
 	return NULL;
 }
 
@@ -376,7 +378,7 @@ static struct dst_entry *subflow_v6_route_req(const struct sock *sk,
 
 	dst_release(dst);
 	if (!req->syncookie)
-		tcp6_request_sock_ops.send_reset(sk, skb);
+		tcp6_request_sock_ops.send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
 	return NULL;
 }
 #endif
@@ -911,7 +913,7 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
 	tcp_rsk(req)->drop_req = true;
 	inet_csk_prepare_for_destroy_sock(child);
 	tcp_done(child);
-	req->rsk_ops->send_reset(sk, skb);
+	req->rsk_ops->send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
 
 	/* The last child reference will be released by the caller */
 	return child;
-- 
2.37.3

[PATCH net-next v7 3/7] rstreason: prepare for active reset

[Jason Xing]

From: Jason Xing <kernelxing@tencent.com>

Like what we did to passive reset:
only passing possible reset reason in each active reset path.

No functional changes.

Signed-off-by: Jason Xing <kernelxing@tencent.com>
---
 include/net/tcp.h     |  3 ++-
 net/ipv4/tcp.c        | 15 ++++++++++-----
 net/ipv4/tcp_output.c |  3 ++-
 net/ipv4/tcp_timer.c  |  9 ++++++---
 net/mptcp/protocol.c  |  4 +++-
 net/mptcp/subflow.c   |  5 +++--
 6 files changed, 26 insertions(+), 13 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index b935e1ae4caf..adeacc9aa28a 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -670,7 +670,8 @@ int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue,
 void tcp_send_probe0(struct sock *);
 int tcp_write_wakeup(struct sock *, int mib);
 void tcp_send_fin(struct sock *sk);
-void tcp_send_active_reset(struct sock *sk, gfp_t priority);
+void tcp_send_active_reset(struct sock *sk, gfp_t priority,
+			   enum sk_rst_reason reason);
 int tcp_send_synack(struct sock *);
 void tcp_push_one(struct sock *, unsigned int mss_now);
 void __tcp_send_ack(struct sock *sk, u32 rcv_nxt);
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index f23b97777ea5..4ec0f4feee00 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -275,6 +275,7 @@
 #include <net/xfrm.h>
 #include <net/ip.h>
 #include <net/sock.h>
+#include <net/rstreason.h>
 
 #include <linux/uaccess.h>
 #include <asm/ioctls.h>
@@ -2811,7 +2812,8 @@ void __tcp_close(struct sock *sk, long timeout)
 		/* Unread data was tossed, zap the connection. */
 		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONCLOSE);
 		tcp_set_state(sk, TCP_CLOSE);
-		tcp_send_active_reset(sk, sk->sk_allocation);
+		tcp_send_active_reset(sk, sk->sk_allocation,
+				      SK_RST_REASON_NOT_SPECIFIED);
 	} else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {
 		/* Check zero linger _after_ checking for unread data. */
 		sk->sk_prot->disconnect(sk, 0);
@@ -2885,7 +2887,8 @@ void __tcp_close(struct sock *sk, long timeout)
 		struct tcp_sock *tp = tcp_sk(sk);
 		if (READ_ONCE(tp->linger2) < 0) {
 			tcp_set_state(sk, TCP_CLOSE);
-			tcp_send_active_reset(sk, GFP_ATOMIC);
+			tcp_send_active_reset(sk, GFP_ATOMIC,
+					      SK_RST_REASON_NOT_SPECIFIED);
 			__NET_INC_STATS(sock_net(sk),
 					LINUX_MIB_TCPABORTONLINGER);
 		} else {
@@ -2903,7 +2906,8 @@ void __tcp_close(struct sock *sk, long timeout)
 	if (sk->sk_state != TCP_CLOSE) {
 		if (tcp_check_oom(sk, 0)) {
 			tcp_set_state(sk, TCP_CLOSE);
-			tcp_send_active_reset(sk, GFP_ATOMIC);
+			tcp_send_active_reset(sk, GFP_ATOMIC,
+					      SK_RST_REASON_NOT_SPECIFIED);
 			__NET_INC_STATS(sock_net(sk),
 					LINUX_MIB_TCPABORTONMEMORY);
 		} else if (!check_net(sock_net(sk))) {
@@ -3007,7 +3011,7 @@ int tcp_disconnect(struct sock *sk, int flags)
 		/* The last check adjusts for discrepancy of Linux wrt. RFC
 		 * states
 		 */
-		tcp_send_active_reset(sk, gfp_any());
+		tcp_send_active_reset(sk, gfp_any(), SK_RST_REASON_NOT_SPECIFIED);
 		WRITE_ONCE(sk->sk_err, ECONNRESET);
 	} else if (old_state == TCP_SYN_SENT)
 		WRITE_ONCE(sk->sk_err, ECONNRESET);
@@ -4564,7 +4568,8 @@ int tcp_abort(struct sock *sk, int err)
 		smp_wmb();
 		sk_error_report(sk);
 		if (tcp_need_reset(sk->sk_state))
-			tcp_send_active_reset(sk, GFP_ATOMIC);
+			tcp_send_active_reset(sk, GFP_ATOMIC,
+					      SK_RST_REASON_NOT_SPECIFIED);
 		tcp_done(sk);
 	}
 
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 61119d42b0fd..276d9d541b01 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -3586,7 +3586,8 @@ void tcp_send_fin(struct sock *sk)
  * was unread data in the receive queue.  This behavior is recommended
  * by RFC 2525, section 2.17.  -DaveM
  */
-void tcp_send_active_reset(struct sock *sk, gfp_t priority)
+void tcp_send_active_reset(struct sock *sk, gfp_t priority,
+			   enum sk_rst_reason reason)
 {
 	struct sk_buff *skb;
 
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 976db57b95d4..83fe7f62f7f1 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -22,6 +22,7 @@
 #include <linux/module.h>
 #include <linux/gfp.h>
 #include <net/tcp.h>
+#include <net/rstreason.h>
 
 static u32 tcp_clamp_rto_to_user_timeout(const struct sock *sk)
 {
@@ -127,7 +128,8 @@ static int tcp_out_of_resources(struct sock *sk, bool do_reset)
 		    (!tp->snd_wnd && !tp->packets_out))
 			do_reset = true;
 		if (do_reset)
-			tcp_send_active_reset(sk, GFP_ATOMIC);
+			tcp_send_active_reset(sk, GFP_ATOMIC,
+					      SK_RST_REASON_NOT_SPECIFIED);
 		tcp_done(sk);
 		__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONMEMORY);
 		return 1;
@@ -768,7 +770,7 @@ static void tcp_keepalive_timer (struct timer_list *t)
 				goto out;
 			}
 		}
-		tcp_send_active_reset(sk, GFP_ATOMIC);
+		tcp_send_active_reset(sk, GFP_ATOMIC, SK_RST_REASON_NOT_SPECIFIED);
 		goto death;
 	}
 
@@ -795,7 +797,8 @@ static void tcp_keepalive_timer (struct timer_list *t)
 		    icsk->icsk_probes_out > 0) ||
 		    (user_timeout == 0 &&
 		    icsk->icsk_probes_out >= keepalive_probes(tp))) {
-			tcp_send_active_reset(sk, GFP_ATOMIC);
+			tcp_send_active_reset(sk, GFP_ATOMIC,
+					      SK_RST_REASON_NOT_SPECIFIED);
 			tcp_write_err(sk);
 			goto out;
 		}
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index f8bc34f0d973..065967086492 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -21,6 +21,7 @@
 #endif
 #include <net/mptcp.h>
 #include <net/xfrm.h>
+#include <net/rstreason.h>
 #include <asm/ioctls.h>
 #include "protocol.h"
 #include "mib.h"
@@ -2569,7 +2570,8 @@ static void mptcp_check_fastclose(struct mptcp_sock *msk)
 
 		slow = lock_sock_fast(tcp_sk);
 		if (tcp_sk->sk_state != TCP_CLOSE) {
-			tcp_send_active_reset(tcp_sk, GFP_ATOMIC);
+			tcp_send_active_reset(tcp_sk, GFP_ATOMIC,
+					      SK_RST_REASON_NOT_SPECIFIED);
 			tcp_set_state(tcp_sk, TCP_CLOSE);
 		}
 		unlock_sock_fast(tcp_sk, slow);
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 32fe2ef36d56..ac867d277860 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -414,7 +414,7 @@ void mptcp_subflow_reset(struct sock *ssk)
 	/* must hold: tcp_done() could drop last reference on parent */
 	sock_hold(sk);
 
-	tcp_send_active_reset(ssk, GFP_ATOMIC);
+	tcp_send_active_reset(ssk, GFP_ATOMIC, SK_RST_REASON_NOT_SPECIFIED);
 	tcp_done(ssk);
 	if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &mptcp_sk(sk)->flags))
 		mptcp_schedule_work(sk);
@@ -1350,7 +1350,8 @@ static bool subflow_check_data_avail(struct sock *ssk)
 			tcp_set_state(ssk, TCP_CLOSE);
 			while ((skb = skb_peek(&ssk->sk_receive_queue)))
 				sk_eat_skb(ssk, skb);
-			tcp_send_active_reset(ssk, GFP_ATOMIC);
+			tcp_send_active_reset(ssk, GFP_ATOMIC,
+					      SK_RST_REASON_NOT_SPECIFIED);
 			WRITE_ONCE(subflow->data_avail, false);
 			return false;
 		}
-- 
2.37.3

[PATCH net-next v7 4/7] tcp: support rstreason for passive reset

[Jason Xing]

From: Jason Xing <kernelxing@tencent.com>

Reuse the dropreason logic to show the exact reason of tcp reset,
so we can finally display the corresponding item in enum sk_reset_reason
instead of reinventing new reset reasons. This patch replaces all
the prior NOT_SPECIFIED reasons.

Signed-off-by: Jason Xing <kernelxing@tencent.com>
---
 net/ipv4/tcp_ipv4.c | 9 +++++----
 net/ipv6/tcp_ipv6.c | 9 +++++----
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 418d11902fa7..06f8a24801b2 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1936,7 +1936,7 @@ int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
 	return 0;
 
 reset:
-	tcp_v4_send_reset(rsk, skb, SK_RST_REASON_NOT_SPECIFIED);
+	tcp_v4_send_reset(rsk, skb, convert_dropreason(reason));
 discard:
 	kfree_skb_reason(skb, reason);
 	/* Be careful here. If this function gets more complicated and
@@ -2278,7 +2278,8 @@ int tcp_v4_rcv(struct sk_buff *skb)
 		} else {
 			drop_reason = tcp_child_process(sk, nsk, skb);
 			if (drop_reason) {
-				tcp_v4_send_reset(nsk, skb, SK_RST_REASON_NOT_SPECIFIED);
+				tcp_v4_send_reset(nsk, skb,
+						  convert_dropreason(drop_reason));
 				goto discard_and_relse;
 			}
 			sock_put(sk);
@@ -2357,7 +2358,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
 bad_packet:
 		__TCP_INC_STATS(net, TCP_MIB_INERRS);
 	} else {
-		tcp_v4_send_reset(NULL, skb, SK_RST_REASON_NOT_SPECIFIED);
+		tcp_v4_send_reset(NULL, skb, convert_dropreason(drop_reason));
 	}
 
 discard_it:
@@ -2409,7 +2410,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
 		tcp_v4_timewait_ack(sk, skb);
 		break;
 	case TCP_TW_RST:
-		tcp_v4_send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
+		tcp_v4_send_reset(sk, skb, convert_dropreason(drop_reason));
 		inet_twsk_deschedule_put(inet_twsk(sk));
 		goto discard_it;
 	case TCP_TW_SUCCESS:;
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 017f6293b5f4..d8c74e90698b 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1680,7 +1680,7 @@ int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
 	return 0;
 
 reset:
-	tcp_v6_send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
+	tcp_v6_send_reset(sk, skb, convert_dropreason(reason));
 discard:
 	if (opt_skb)
 		__kfree_skb(opt_skb);
@@ -1865,7 +1865,8 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
 		} else {
 			drop_reason = tcp_child_process(sk, nsk, skb);
 			if (drop_reason) {
-				tcp_v6_send_reset(nsk, skb, SK_RST_REASON_NOT_SPECIFIED);
+				tcp_v6_send_reset(nsk, skb,
+						  convert_dropreason(drop_reason));
 				goto discard_and_relse;
 			}
 			sock_put(sk);
@@ -1942,7 +1943,7 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
 bad_packet:
 		__TCP_INC_STATS(net, TCP_MIB_INERRS);
 	} else {
-		tcp_v6_send_reset(NULL, skb, SK_RST_REASON_NOT_SPECIFIED);
+		tcp_v6_send_reset(NULL, skb, convert_dropreason(drop_reason));
 	}
 
 discard_it:
@@ -1998,7 +1999,7 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
 		tcp_v6_timewait_ack(sk, skb);
 		break;
 	case TCP_TW_RST:
-		tcp_v6_send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
+		tcp_v6_send_reset(sk, skb, convert_dropreason(drop_reason));
 		inet_twsk_deschedule_put(inet_twsk(sk));
 		goto discard_it;
 	case TCP_TW_SUCCESS:
-- 
2.37.3

[PATCH net-next v7 5/7] mptcp: support rstreason for passive reset

[Jason Xing]

From: Jason Xing <kernelxing@tencent.com>

It relys on what reset options in the skb are as rfc8684 says. Reusing
this logic can save us much energy. This patch replaces most of the prior
NOT_SPECIFIED reasons.

Signed-off-by: Jason Xing <kernelxing@tencent.com>
---
 net/mptcp/subflow.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index ac867d277860..54e4b2515517 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -309,8 +309,13 @@ static struct dst_entry *subflow_v4_route_req(const struct sock *sk,
 		return dst;
 
 	dst_release(dst);
-	if (!req->syncookie)
-		tcp_request_sock_ops.send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
+	if (!req->syncookie) {
+		struct mptcp_ext *mpext = mptcp_get_ext(skb);
+		enum sk_rst_reason reason;
+
+		reason = convert_mptcpreason(mpext->reset_reason);
+		tcp_request_sock_ops.send_reset(sk, skb, reason);
+	}
 	return NULL;
 }
 
@@ -377,8 +382,13 @@ static struct dst_entry *subflow_v6_route_req(const struct sock *sk,
 		return dst;
 
 	dst_release(dst);
-	if (!req->syncookie)
-		tcp6_request_sock_ops.send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
+	if (!req->syncookie) {
+		struct mptcp_ext *mpext = mptcp_get_ext(skb);
+		enum sk_rst_reason reason;
+
+		reason = convert_mptcpreason(mpext->reset_reason);
+		tcp6_request_sock_ops.send_reset(sk, skb, reason);
+	}
 	return NULL;
 }
 #endif
@@ -783,6 +793,7 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
 	struct mptcp_subflow_request_sock *subflow_req;
 	struct mptcp_options_received mp_opt;
 	bool fallback, fallback_is_fatal;
+	enum sk_rst_reason reason;
 	struct mptcp_sock *owner;
 	struct sock *child;
 
@@ -913,7 +924,8 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
 	tcp_rsk(req)->drop_req = true;
 	inet_csk_prepare_for_destroy_sock(child);
 	tcp_done(child);
-	req->rsk_ops->send_reset(sk, skb, SK_RST_REASON_NOT_SPECIFIED);
+	reason = convert_mptcpreason(mptcp_get_ext(skb)->reset_reason);
+	req->rsk_ops->send_reset(sk, skb, reason);
 
 	/* The last child reference will be released by the caller */
 	return child;
-- 
2.37.3

[PATCH net-next v7 6/7] mptcp: introducing a helper into active reset logic

[Jason Xing]

From: Jason Xing <kernelxing@tencent.com>

Since we have mapped every mptcp reset reason definition in enum
sk_rst_reason, introducing a new helper can cover some missing places
where we have already set the subflow->reset_reason.

Note: using SK_RST_REASON_NOT_SPECIFIED is the same as
SK_RST_REASON_MPTCP_RST_EUNSPEC. They are both unknown. So we can convert
it directly.

Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Jason Xing <kernelxing@tencent.com>
---
Link: https://lore.kernel.org/all/2d3ea199eef53cf6a0c48e21abdee0eefbdee927.camel@redhat.com/
---
 net/mptcp/protocol.c |  4 +---
 net/mptcp/protocol.h | 11 +++++++++++
 net/mptcp/subflow.c  |  6 ++----
 3 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 065967086492..4b13ca362efa 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -21,7 +21,6 @@
 #endif
 #include <net/mptcp.h>
 #include <net/xfrm.h>
-#include <net/rstreason.h>
 #include <asm/ioctls.h>
 #include "protocol.h"
 #include "mib.h"
@@ -2570,8 +2569,7 @@ static void mptcp_check_fastclose(struct mptcp_sock *msk)
 
 		slow = lock_sock_fast(tcp_sk);
 		if (tcp_sk->sk_state != TCP_CLOSE) {
-			tcp_send_active_reset(tcp_sk, GFP_ATOMIC,
-					      SK_RST_REASON_NOT_SPECIFIED);
+			mptcp_send_active_reset_reason(tcp_sk);
 			tcp_set_state(tcp_sk, TCP_CLOSE);
 		}
 		unlock_sock_fast(tcp_sk, slow);
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index fdfa843e2d88..d4f83f1c6880 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -12,6 +12,7 @@
 #include <net/inet_connection_sock.h>
 #include <uapi/linux/mptcp.h>
 #include <net/genetlink.h>
+#include <net/rstreason.h>
 
 #include "mptcp_pm_gen.h"
 
@@ -581,6 +582,16 @@ mptcp_subflow_ctx_reset(struct mptcp_subflow_context *subflow)
 	WRITE_ONCE(subflow->local_id, -1);
 }
 
+static inline void
+mptcp_send_active_reset_reason(struct sock *sk)
+{
+	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+	enum sk_rst_reason reason;
+
+	reason = convert_mptcpreason(subflow->reset_reason);
+	tcp_send_active_reset(sk, GFP_ATOMIC, reason);
+}
+
 static inline u64
 mptcp_subflow_get_map_offset(const struct mptcp_subflow_context *subflow)
 {
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 54e4b2515517..423c842086ff 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -20,7 +20,6 @@
 #include <net/transp_v6.h>
 #endif
 #include <net/mptcp.h>
-#include <net/rstreason.h>
 
 #include "protocol.h"
 #include "mib.h"
@@ -424,7 +423,7 @@ void mptcp_subflow_reset(struct sock *ssk)
 	/* must hold: tcp_done() could drop last reference on parent */
 	sock_hold(sk);
 
-	tcp_send_active_reset(ssk, GFP_ATOMIC, SK_RST_REASON_NOT_SPECIFIED);
+	mptcp_send_active_reset_reason(ssk);
 	tcp_done(ssk);
 	if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &mptcp_sk(sk)->flags))
 		mptcp_schedule_work(sk);
@@ -1362,8 +1361,7 @@ static bool subflow_check_data_avail(struct sock *ssk)
 			tcp_set_state(ssk, TCP_CLOSE);
 			while ((skb = skb_peek(&ssk->sk_receive_queue)))
 				sk_eat_skb(ssk, skb);
-			tcp_send_active_reset(ssk, GFP_ATOMIC,
-					      SK_RST_REASON_NOT_SPECIFIED);
+			mptcp_send_active_reset_reason(ssk);
 			WRITE_ONCE(subflow->data_avail, false);
 			return false;
 		}
-- 
2.37.3

[PATCH net-next v7 7/7] rstreason: make it work in trace world

[Jason Xing]

From: Jason Xing <kernelxing@tencent.com>

At last, we should let it work by introducing this reset reason in
trace world.

One of the possible expected outputs is:
... tcp_send_reset: skbaddr=xxx skaddr=xxx src=xxx dest=xxx
state=TCP_ESTABLISHED reason=NOT_SPECIFIED

Signed-off-by: Jason Xing <kernelxing@tencent.com>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 include/trace/events/tcp.h | 26 ++++++++++++++++++++++----
 net/ipv4/tcp_ipv4.c        |  2 +-
 net/ipv4/tcp_output.c      |  2 +-
 net/ipv6/tcp_ipv6.c        |  2 +-
 4 files changed, 25 insertions(+), 7 deletions(-)

diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h
index 5c04a61a11c2..49b5ee091cf6 100644
--- a/include/trace/events/tcp.h
+++ b/include/trace/events/tcp.h
@@ -11,6 +11,7 @@
 #include <net/ipv6.h>
 #include <net/tcp.h>
 #include <linux/sock_diag.h>
+#include <net/rstreason.h>
 
 /*
  * tcp event with arguments sk and skb
@@ -74,20 +75,32 @@ DEFINE_EVENT(tcp_event_sk_skb, tcp_retransmit_skb,
 	TP_ARGS(sk, skb)
 );
 
+#undef FN
+#define FN(reason)	TRACE_DEFINE_ENUM(SK_RST_REASON_##reason);
+DEFINE_RST_REASON(FN, FN)
+
+#undef FN
+#undef FNe
+#define FN(reason)	{ SK_RST_REASON_##reason, #reason },
+#define FNe(reason)	{ SK_RST_REASON_##reason, #reason }
+
 /*
  * skb of trace_tcp_send_reset is the skb that caused RST. In case of
  * active reset, skb should be NULL
  */
 TRACE_EVENT(tcp_send_reset,
 
-	TP_PROTO(const struct sock *sk, const struct sk_buff *skb),
+	TP_PROTO(const struct sock *sk,
+		 const struct sk_buff *skb,
+		 const enum sk_rst_reason reason),
 
-	TP_ARGS(sk, skb),
+	TP_ARGS(sk, skb, reason),
 
 	TP_STRUCT__entry(
 		__field(const void *, skbaddr)
 		__field(const void *, skaddr)
 		__field(int, state)
+		__field(enum sk_rst_reason, reason)
 		__array(__u8, saddr, sizeof(struct sockaddr_in6))
 		__array(__u8, daddr, sizeof(struct sockaddr_in6))
 	),
@@ -113,14 +126,19 @@ TRACE_EVENT(tcp_send_reset,
 			 */
 			TP_STORE_ADDR_PORTS_SKB(skb, th, entry->daddr, entry->saddr);
 		}
+		__entry->reason = reason;
 	),
 
-	TP_printk("skbaddr=%p skaddr=%p src=%pISpc dest=%pISpc state=%s",
+	TP_printk("skbaddr=%p skaddr=%p src=%pISpc dest=%pISpc state=%s reason=%s",
 		  __entry->skbaddr, __entry->skaddr,
 		  __entry->saddr, __entry->daddr,
-		  __entry->state ? show_tcp_state_name(__entry->state) : "UNKNOWN")
+		  __entry->state ? show_tcp_state_name(__entry->state) : "UNKNOWN",
+		  __print_symbolic(__entry->reason, DEFINE_RST_REASON(FN, FNe)))
 );
 
+#undef FN
+#undef FNe
+
 /*
  * tcp event with arguments sk
  *
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 06f8a24801b2..5db2d55b65af 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -871,7 +871,7 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb,
 	if (sk)
 		arg.bound_dev_if = sk->sk_bound_dev_if;
 
-	trace_tcp_send_reset(sk, skb);
+	trace_tcp_send_reset(sk, skb, reason);
 
 	BUILD_BUG_ON(offsetof(struct sock, sk_bound_dev_if) !=
 		     offsetof(struct inet_timewait_sock, tw_bound_dev_if));
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 276d9d541b01..b08ffb17d5a0 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -3612,7 +3612,7 @@ void tcp_send_active_reset(struct sock *sk, gfp_t priority,
 	/* skb of trace_tcp_send_reset() keeps the skb that caused RST,
 	 * skb here is different to the troublesome skb, so use NULL
 	 */
-	trace_tcp_send_reset(sk, NULL);
+	trace_tcp_send_reset(sk, NULL, SK_RST_REASON_NOT_SPECIFIED);
 }
 
 /* Send a crossed SYN-ACK during socket establishment.
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index d8c74e90698b..966a6a9b0f44 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1133,7 +1133,7 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb,
 			label = ip6_flowlabel(ipv6h);
 	}
 
-	trace_tcp_send_reset(sk, skb);
+	trace_tcp_send_reset(sk, skb, reason);
 
 	tcp_v6_send_response(sk, skb, seq, ack_seq, 0, 0, 0, oif, 1,
 			     ipv6_get_dsfield(ipv6h), label, priority, txhash,
-- 
2.37.3

Re: [PATCH net-next v7 0/7] Implement reset reason mechanism to detect

[MPTCP CI]

Hi Jason,

Thank you for your modifications, that's great!

Our CI did some validations and here is its report:

- KVM Validation: normal: Success! ✅
- KVM Validation: debug: Success! ✅
- KVM Validation: btf (only bpftest_all): Success! ✅
- Task: https://github.com/multipath-tcp/mptcp_net-next/actions/runs/8777989860

Initiator: Patchew Applier
Commits: https://github.com/multipath-tcp/mptcp_net-next/commits/e8bb33fa75b4
Patchwork: https://patchwork.kernel.org/project/mptcp/list/?series=846464


If there are some issues, you can reproduce them using the same environment as
the one used by the CI thanks to a docker image, e.g.:

    $ cd [kernel source code]
    $ docker run -v "${PWD}:${PWD}:rw" -w "${PWD}" --privileged --rm -it \
        --pull always mptcp/mptcp-upstream-virtme-docker:latest \
        auto-normal

For more details:

    https://github.com/multipath-tcp/mptcp-upstream-virtme-docker


Please note that despite all the efforts that have been already done to have a
stable tests suite when executed on a public CI like here, it is possible some
reported issues are not due to your modifications. Still, do not hesitate to
help us improve that ;-)

Cheers,
MPTCP GH Action bot
Bot operated by Matthieu Baerts (NGI0 Core)

Re: [PATCH net-next v7 1/7] net: introduce rstreason to detect why the RST is sent

[Matthieu Baerts]

Hi Jason,

On 22/04/2024 05:01, Jason Xing wrote:
> From: Jason Xing <kernelxing@tencent.com>
> 
> Add a new standalone file for the easy future extension to support
> both active reset and passive reset in the TCP/DCCP/MPTCP protocols.

Thank you for looking at that!

(...)

> diff --git a/include/net/rstreason.h b/include/net/rstreason.h
> new file mode 100644
> index 000000000000..c57bc5413c17
> --- /dev/null
> +++ b/include/net/rstreason.h
> @@ -0,0 +1,144 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +
> +#ifndef _LINUX_RSTREASON_H
> +#define _LINUX_RSTREASON_H
> +#include <net/dropreason-core.h>
> +#include <uapi/linux/mptcp.h>
> +
> +#define DEFINE_RST_REASON(FN, FNe)	\
> +	FN(MPTCP_RST_EUNSPEC)		\
> +	FN(MPTCP_RST_EMPTCP)		\
> +	FN(MPTCP_RST_ERESOURCE)		\
> +	FN(MPTCP_RST_EPROHIBIT)		\
> +	FN(MPTCP_RST_EWQ2BIG)		\
> +	FN(MPTCP_RST_EBADPERF)		\
> +	FN(MPTCP_RST_EMIDDLEBOX)	\

Small detail: should it not make more sense to put the ones linked to
MPTCP at the end? I mean I guess MPTCP should be treated in second
priority: CONFIG_MPTCP could not be set, and the ones linked to TCP
should be more frequent, etc.

> +	FN(NOT_SPECIFIED)		\
> +	FN(NO_SOCKET)			\
> +	FNe(MAX)

(...)

> +/* Convert reset reasons in MPTCP to our own enum type */
> +static inline enum sk_rst_reason convert_mptcpreason(u32 reason)
> +{
> +	switch (reason) {
> +	case MPTCP_RST_EUNSPEC:
> +		return SK_RST_REASON_MPTCP_RST_EUNSPEC;
> +	case MPTCP_RST_EMPTCP:
> +		return SK_RST_REASON_MPTCP_RST_EMPTCP;
> +	case MPTCP_RST_ERESOURCE:
> +		return SK_RST_REASON_MPTCP_RST_ERESOURCE;
> +	case MPTCP_RST_EPROHIBIT:
> +		return SK_RST_REASON_MPTCP_RST_EPROHIBIT;
> +	case MPTCP_RST_EWQ2BIG:
> +		return SK_RST_REASON_MPTCP_RST_EWQ2BIG;
> +	case MPTCP_RST_EBADPERF:
> +		return SK_RST_REASON_MPTCP_RST_EBADPERF;
> +	case MPTCP_RST_EMIDDLEBOX:
> +		return SK_RST_REASON_MPTCP_RST_EMIDDLEBOX;
> +	default:
> +		/**
> +		 * It should not happen, or else errors may occur
> +		 * in MPTCP layer
> +		 */
> +		return SK_RST_REASON_ERROR;
> +	}
> +}

If this helper is only used on MPTCP, maybe better to move it to
net/mptcp/protocol.h (and to patch 5/7?)? We tried to isolate MPTCP code.

Also, maybe it is just me, but I'm not a big fan of the helper name:
convert_mptcpreason() (same for the "drop" one). I think it should at
least mention its "origin" (rst reason): e.g. something like
(sk_)rst_reason_convert_mptcp or (sk_)rst_convert_mptcp_reason() (or
mptcp_to_rst_reason())?

And (sk_)rst_reason_convert_(skb_)drop() (or skb_drop_to_rst_reason())?

> +/* Convert reset reasons in MPTCP to our own enum type */

I don't think this part is linked to MPTCP, right?

> +static inline enum sk_rst_reason convert_dropreason(enum skb_drop_reason reason)
> +{
> +	switch (reason) {
> +	case SKB_DROP_REASON_NOT_SPECIFIED:
> +		return SK_RST_REASON_NOT_SPECIFIED;
> +	case SKB_DROP_REASON_NO_SOCKET:
> +		return SK_RST_REASON_NO_SOCKET;
> +	default:
> +		/* If we don't have our own corresponding reason */
> +		return SK_RST_REASON_NOT_SPECIFIED;
> +	}
> +}

(This helper could be introduced in patch 4/7 because it is not used
before, but I'm fine either ways.)

> +#endif

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.

Re: [PATCH net-next v7 1/7] net: introduce rstreason to detect why the RST is sent

[Jason Xing]

Hello Matthieu,

On Mon, Apr 22, 2024 at 4:47 PM Matthieu Baerts <matttbe@kernel.org> wrote:
>
> Hi Jason,
>
> On 22/04/2024 05:01, Jason Xing wrote:
> > From: Jason Xing <kernelxing@tencent.com>
> >
> > Add a new standalone file for the easy future extension to support
> > both active reset and passive reset in the TCP/DCCP/MPTCP protocols.
>
> Thank you for looking at that!

Thanks for the review!

>
> (...)
>
> > diff --git a/include/net/rstreason.h b/include/net/rstreason.h
> > new file mode 100644
> > index 000000000000..c57bc5413c17
> > --- /dev/null
> > +++ b/include/net/rstreason.h
> > @@ -0,0 +1,144 @@
> > +/* SPDX-License-Identifier: GPL-2.0-or-later */
> > +
> > +#ifndef _LINUX_RSTREASON_H
> > +#define _LINUX_RSTREASON_H
> > +#include <net/dropreason-core.h>
> > +#include <uapi/linux/mptcp.h>
> > +
> > +#define DEFINE_RST_REASON(FN, FNe)   \
> > +     FN(MPTCP_RST_EUNSPEC)           \
> > +     FN(MPTCP_RST_EMPTCP)            \
> > +     FN(MPTCP_RST_ERESOURCE)         \
> > +     FN(MPTCP_RST_EPROHIBIT)         \
> > +     FN(MPTCP_RST_EWQ2BIG)           \
> > +     FN(MPTCP_RST_EBADPERF)          \
> > +     FN(MPTCP_RST_EMIDDLEBOX)        \
>
> Small detail: should it not make more sense to put the ones linked to
> MPTCP at the end? I mean I guess MPTCP should be treated in second
> priority: CONFIG_MPTCP could not be set, and the ones linked to TCP
> should be more frequent, etc.

Do you mean that I need to adjust the order: 1) tcp reasons first, 2)
independent reasons, 3) mptcp reasons ?

Reasonable. I will do it :)

>
> > +     FN(NOT_SPECIFIED)               \
> > +     FN(NO_SOCKET)                   \
> > +     FNe(MAX)
>
> (...)
>
> > +/* Convert reset reasons in MPTCP to our own enum type */
> > +static inline enum sk_rst_reason convert_mptcpreason(u32 reason)
> > +{
> > +     switch (reason) {
> > +     case MPTCP_RST_EUNSPEC:
> > +             return SK_RST_REASON_MPTCP_RST_EUNSPEC;
> > +     case MPTCP_RST_EMPTCP:
> > +             return SK_RST_REASON_MPTCP_RST_EMPTCP;
> > +     case MPTCP_RST_ERESOURCE:
> > +             return SK_RST_REASON_MPTCP_RST_ERESOURCE;
> > +     case MPTCP_RST_EPROHIBIT:
> > +             return SK_RST_REASON_MPTCP_RST_EPROHIBIT;
> > +     case MPTCP_RST_EWQ2BIG:
> > +             return SK_RST_REASON_MPTCP_RST_EWQ2BIG;
> > +     case MPTCP_RST_EBADPERF:
> > +             return SK_RST_REASON_MPTCP_RST_EBADPERF;
> > +     case MPTCP_RST_EMIDDLEBOX:
> > +             return SK_RST_REASON_MPTCP_RST_EMIDDLEBOX;
> > +     default:
> > +             /**
> > +              * It should not happen, or else errors may occur
> > +              * in MPTCP layer
> > +              */
> > +             return SK_RST_REASON_ERROR;
> > +     }
> > +}
>
> If this helper is only used on MPTCP, maybe better to move it to
> net/mptcp/protocol.h (and to patch 5/7?)? We tried to isolate MPTCP code.

Roger that. I will move the helper into protocol.h as well as the patch itself.

>
> Also, maybe it is just me, but I'm not a big fan of the helper name:
> convert_mptcpreason() (same for the "drop" one). I think it should at
> least mention its "origin" (rst reason): e.g. something like
> (sk_)rst_reason_convert_mptcp or (sk_)rst_convert_mptcp_reason() (or
> mptcp_to_rst_reason())?
>
> And (sk_)rst_reason_convert_(skb_)drop() (or skb_drop_to_rst_reason())?

I agree with you. Actually I had a local patch where I used
sk_rst_reason_skbdrop() and sk_rst_reason_mptcpreason().
Interestingly, I changed them in this patch series due to the function
name being too long (which is my initial thought).

I will use sk_rst_convert_xxx_reason() as you suggested.

>
> > +/* Convert reset reasons in MPTCP to our own enum type */
>
> I don't think this part is linked to MPTCP, right?

Ah, copy-paste syndrome... Sorry, I will correct it.

>
> > +static inline enum sk_rst_reason convert_dropreason(enum skb_drop_reason reason)
> > +{
> > +     switch (reason) {
> > +     case SKB_DROP_REASON_NOT_SPECIFIED:
> > +             return SK_RST_REASON_NOT_SPECIFIED;
> > +     case SKB_DROP_REASON_NO_SOCKET:
> > +             return SK_RST_REASON_NO_SOCKET;
> > +     default:
> > +             /* If we don't have our own corresponding reason */
> > +             return SK_RST_REASON_NOT_SPECIFIED;
> > +     }
> > +}
>
> (This helper could be introduced in patch 4/7 because it is not used
> before, but I'm fine either ways.)

Good. It makes more sense.

Thanks,
Jason

Re: [PATCH net-next v7 1/7] net: introduce rstreason to detect why the RST is sent

[Matthieu Baerts]

On 22/04/2024 11:17, Jason Xing wrote:> On Mon, Apr 22, 2024 at 4:47 PM
Matthieu Baerts <matttbe@kernel.org> wrote:
>> On 22/04/2024 05:01, Jason Xing wrote:
>>> From: Jason Xing <kernelxing@tencent.com>

(...)

>>> diff --git a/include/net/rstreason.h b/include/net/rstreason.h
>>> new file mode 100644
>>> index 000000000000..c57bc5413c17
>>> --- /dev/null
>>> +++ b/include/net/rstreason.h
>>> @@ -0,0 +1,144 @@
>>> +/* SPDX-License-Identifier: GPL-2.0-or-later */
>>> +
>>> +#ifndef _LINUX_RSTREASON_H
>>> +#define _LINUX_RSTREASON_H
>>> +#include <net/dropreason-core.h>
>>> +#include <uapi/linux/mptcp.h>
>>> +
>>> +#define DEFINE_RST_REASON(FN, FNe)   \
>>> +     FN(MPTCP_RST_EUNSPEC)           \
>>> +     FN(MPTCP_RST_EMPTCP)            \
>>> +     FN(MPTCP_RST_ERESOURCE)         \
>>> +     FN(MPTCP_RST_EPROHIBIT)         \
>>> +     FN(MPTCP_RST_EWQ2BIG)           \
>>> +     FN(MPTCP_RST_EBADPERF)          \
>>> +     FN(MPTCP_RST_EMIDDLEBOX)        \
>>
>> Small detail: should it not make more sense to put the ones linked to
>> MPTCP at the end? I mean I guess MPTCP should be treated in second
>> priority: CONFIG_MPTCP could not be set, and the ones linked to TCP
>> should be more frequent, etc.
> 
> Do you mean that I need to adjust the order: 1) tcp reasons first, 2)
> independent reasons, 3) mptcp reasons ?

Correct, it looks like it is a more "natural" order.

> Reasonable. I will do it :)

Thanks!

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.

Re: [PATCH net-next v7 1/7] net: introduce rstreason to detect why the RST is sent

[Simon Horman]

On Mon, Apr 22, 2024 at 11:01:03AM +0800, Jason Xing wrote:

...

> diff --git a/include/net/rstreason.h b/include/net/rstreason.h

...

> +/**
> + * There are three parts in order:
> + * 1) reset reason in MPTCP: only for MPTCP use
> + * 2) skb drop reason: relying on drop reasons for such as passive reset
> + * 3) independent reset reason: such as active reset reasons
> + */

Hi Jason,

A minor nit from my side.

'/**' denotes the beginning of a Kernel doc,
but other than that, this comment is not a Kernel doc.

FWIIW, I would suggest providing a proper Kernel doc for enum sk_rst_reason.
But another option would be to simply make this a normal comment,
starting with "/* There are"

> +enum sk_rst_reason {

...

Re: [PATCH net-next v7 1/7] net: introduce rstreason to detect why the RST is sent

[Jason Xing]

Hi Simon,

On Tue, Apr 23, 2024 at 2:28 AM Simon Horman <horms@kernel.org> wrote:
>
> On Mon, Apr 22, 2024 at 11:01:03AM +0800, Jason Xing wrote:
>
> ...
>
> > diff --git a/include/net/rstreason.h b/include/net/rstreason.h
>
> ...
>
> > +/**
> > + * There are three parts in order:
> > + * 1) reset reason in MPTCP: only for MPTCP use
> > + * 2) skb drop reason: relying on drop reasons for such as passive reset
> > + * 3) independent reset reason: such as active reset reasons
> > + */
>
> Hi Jason,
>
> A minor nit from my side.
>
> '/**' denotes the beginning of a Kernel doc,
> but other than that, this comment is not a Kernel doc.
>
> FWIIW, I would suggest providing a proper Kernel doc for enum sk_rst_reason.
> But another option would be to simply make this a normal comment,
> starting with "/* There are"

Thanks Simon. I'm trying to use the kdoc way to make it right :)

How about this one:
/**
 * enum sk_rst_reason - the reasons of socket reset
 *
 * The reason of skb drop, which is used in DCCP/TCP/MPTCP protocols.
 *
 * There are three parts in order:
 * 1) skb drop reasons: relying on drop reasons for such as passive
reset
 * 2) independent reset reasons: such as active reset reasons
 * 3) reset reasons in MPTCP: only for MPTCP use
 */
?

I chose to mimic what enum skb_drop_reason does in the
include/net/dropreason-core.h file.

> +enum sk_rst_reason {
> +       /**
> +        * Copy from include/uapi/linux/mptcp.h.
> +        * These reset fields will not be changed since they adhere to
> +        * RFC 8684. So do not touch them. I'm going to list each definition
> +        * of them respectively.
> +        */

Thanks to you, I found another similar point where I smell something
wrong as in the above code. I'm going to replace '/**' with '/*' since
it's only a comment, not a kdoc.

Thanks,
Jason

Re: [PATCH net-next v7 1/7] net: introduce rstreason to detect why the RST is sent

[Jason Xing]

On Tue, Apr 23, 2024 at 10:14 AM Jason Xing <kerneljasonxing@gmail.com> wrote:
>
> Hi Simon,
>
> On Tue, Apr 23, 2024 at 2:28 AM Simon Horman <horms@kernel.org> wrote:
> >
> > On Mon, Apr 22, 2024 at 11:01:03AM +0800, Jason Xing wrote:
> >
> > ...
> >
> > > diff --git a/include/net/rstreason.h b/include/net/rstreason.h
> >
> > ...
> >
> > > +/**
> > > + * There are three parts in order:
> > > + * 1) reset reason in MPTCP: only for MPTCP use
> > > + * 2) skb drop reason: relying on drop reasons for such as passive reset
> > > + * 3) independent reset reason: such as active reset reasons
> > > + */
> >
> > Hi Jason,
> >
> > A minor nit from my side.
> >
> > '/**' denotes the beginning of a Kernel doc,
> > but other than that, this comment is not a Kernel doc.
> >
> > FWIIW, I would suggest providing a proper Kernel doc for enum sk_rst_reason.
> > But another option would be to simply make this a normal comment,
> > starting with "/* There are"
>
> Thanks Simon. I'm trying to use the kdoc way to make it right :)
>
> How about this one:
> /**
>  * enum sk_rst_reason - the reasons of socket reset
>  *
>  * The reason of skb drop, which is used in DCCP/TCP/MPTCP protocols.

s/skb drop/sk reset/

Sorry, I cannot withdraw my previous email in time.

>  *
>  * There are three parts in order:
>  * 1) skb drop reasons: relying on drop reasons for such as passive
> reset
>  * 2) independent reset reasons: such as active reset reasons
>  * 3) reset reasons in MPTCP: only for MPTCP use
>  */
> ?
>
> I chose to mimic what enum skb_drop_reason does in the
> include/net/dropreason-core.h file.
>
> > +enum sk_rst_reason {
> > +       /**
> > +        * Copy from include/uapi/linux/mptcp.h.
> > +        * These reset fields will not be changed since they adhere to
> > +        * RFC 8684. So do not touch them. I'm going to list each definition
> > +        * of them respectively.
> > +        */
>
> Thanks to you, I found another similar point where I smell something
> wrong as in the above code. I'm going to replace '/**' with '/*' since
> it's only a comment, not a kdoc.
>
> Thanks,
> Jason

Re: [PATCH net-next v7 1/7] net: introduce rstreason to detect why the RST is sent

[Simon Horman]

On Tue, Apr 23, 2024 at 10:17:31AM +0800, Jason Xing wrote:
> On Tue, Apr 23, 2024 at 10:14 AM Jason Xing <kerneljasonxing@gmail.com> wrote:
> >
> > Hi Simon,
> >
> > On Tue, Apr 23, 2024 at 2:28 AM Simon Horman <horms@kernel.org> wrote:
> > >
> > > On Mon, Apr 22, 2024 at 11:01:03AM +0800, Jason Xing wrote:
> > >
> > > ...
> > >
> > > > diff --git a/include/net/rstreason.h b/include/net/rstreason.h
> > >
> > > ...
> > >
> > > > +/**
> > > > + * There are three parts in order:
> > > > + * 1) reset reason in MPTCP: only for MPTCP use
> > > > + * 2) skb drop reason: relying on drop reasons for such as passive reset
> > > > + * 3) independent reset reason: such as active reset reasons
> > > > + */
> > >
> > > Hi Jason,
> > >
> > > A minor nit from my side.
> > >
> > > '/**' denotes the beginning of a Kernel doc,
> > > but other than that, this comment is not a Kernel doc.
> > >
> > > FWIIW, I would suggest providing a proper Kernel doc for enum sk_rst_reason.
> > > But another option would be to simply make this a normal comment,
> > > starting with "/* There are"
> >
> > Thanks Simon. I'm trying to use the kdoc way to make it right :)
> >
> > How about this one:
> > /**
> >  * enum sk_rst_reason - the reasons of socket reset
> >  *
> >  * The reason of skb drop, which is used in DCCP/TCP/MPTCP protocols.
> 
> s/skb drop/sk reset/
> 
> Sorry, I cannot withdraw my previous email in time.
> 
> >  *
> >  * There are three parts in order:
> >  * 1) skb drop reasons: relying on drop reasons for such as passive
> > reset
> >  * 2) independent reset reasons: such as active reset reasons
> >  * 3) reset reasons in MPTCP: only for MPTCP use
> >  */
> > ?
> >
> > I chose to mimic what enum skb_drop_reason does in the
> > include/net/dropreason-core.h file.
> >
> > > +enum sk_rst_reason {
> > > +       /**
> > > +        * Copy from include/uapi/linux/mptcp.h.
> > > +        * These reset fields will not be changed since they adhere to
> > > +        * RFC 8684. So do not touch them. I'm going to list each definition
> > > +        * of them respectively.
> > > +        */
> >
> > Thanks to you, I found another similar point where I smell something
> > wrong as in the above code. I'm going to replace '/**' with '/*' since
> > it's only a comment, not a kdoc.

Likewise, thanks Jason.

I haven't had time to look at v8 properly,
but I see that kernel-doc is happy with the changed
you have made there as discussed above.

Re: [PATCH net-next v7 1/7] net: introduce rstreason to detect why the RST is sent

[Jason Xing]

On Tue, Apr 23, 2024 at 7:57 PM Simon Horman <horms@kernel.org> wrote:
>
> On Tue, Apr 23, 2024 at 10:17:31AM +0800, Jason Xing wrote:
> > On Tue, Apr 23, 2024 at 10:14 AM Jason Xing <kerneljasonxing@gmail.com> wrote:
> > >
> > > Hi Simon,
> > >
> > > On Tue, Apr 23, 2024 at 2:28 AM Simon Horman <horms@kernel.org> wrote:
> > > >
> > > > On Mon, Apr 22, 2024 at 11:01:03AM +0800, Jason Xing wrote:
> > > >
> > > > ...
> > > >
> > > > > diff --git a/include/net/rstreason.h b/include/net/rstreason.h
> > > >
> > > > ...
> > > >
> > > > > +/**
> > > > > + * There are three parts in order:
> > > > > + * 1) reset reason in MPTCP: only for MPTCP use
> > > > > + * 2) skb drop reason: relying on drop reasons for such as passive reset
> > > > > + * 3) independent reset reason: such as active reset reasons
> > > > > + */
> > > >
> > > > Hi Jason,
> > > >
> > > > A minor nit from my side.
> > > >
> > > > '/**' denotes the beginning of a Kernel doc,
> > > > but other than that, this comment is not a Kernel doc.
> > > >
> > > > FWIIW, I would suggest providing a proper Kernel doc for enum sk_rst_reason.
> > > > But another option would be to simply make this a normal comment,
> > > > starting with "/* There are"
> > >
> > > Thanks Simon. I'm trying to use the kdoc way to make it right :)
> > >
> > > How about this one:
> > > /**
> > >  * enum sk_rst_reason - the reasons of socket reset
> > >  *
> > >  * The reason of skb drop, which is used in DCCP/TCP/MPTCP protocols.
> >
> > s/skb drop/sk reset/
> >
> > Sorry, I cannot withdraw my previous email in time.
> >
> > >  *
> > >  * There are three parts in order:
> > >  * 1) skb drop reasons: relying on drop reasons for such as passive
> > > reset
> > >  * 2) independent reset reasons: such as active reset reasons
> > >  * 3) reset reasons in MPTCP: only for MPTCP use
> > >  */
> > > ?
> > >
> > > I chose to mimic what enum skb_drop_reason does in the
> > > include/net/dropreason-core.h file.
> > >
> > > > +enum sk_rst_reason {
> > > > +       /**
> > > > +        * Copy from include/uapi/linux/mptcp.h.
> > > > +        * These reset fields will not be changed since they adhere to
> > > > +        * RFC 8684. So do not touch them. I'm going to list each definition
> > > > +        * of them respectively.
> > > > +        */
> > >
> > > Thanks to you, I found another similar point where I smell something
> > > wrong as in the above code. I'm going to replace '/**' with '/*' since
> > > it's only a comment, not a kdoc.
>
> Likewise, thanks Jason.
>
> I haven't had time to look at v8 properly,
> but I see that kernel-doc is happy with the changed
> you have made there as discussed above.
>

Thank you, Simon. I learned something new about the coding style.

Besides, some other nit problems have been spotted by Matt. I will fix
them if it's required to send a new version.