From: Karsten Graul <kgraul@linux.ibm.com>
Date: Mon, 4 May 2020 14:18:39 +0200
Subject: net/smc: send failover validation message
Git-commit: 29bd73dba4f72970895a2459f7190d388f5204f7
Patch-mainline: v5.8-rc1
References: jsc#SLE-13763

When a connection is switched to a new link then a link validation
message must be sent to the peer over the new link, containing the
sequence number of the last CDC message that was sent over the old link.
The peer will validate if this sequence number is the same or lower then
the number he received, and abort the connection if messages were lost.
Add smcr_cdc_msg_send_validation() to send the message validation
message and call it when a connection was switched in
smc_switch_cursor().

Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Reviewed-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 net/smc/smc_cdc.c  |   25 +++++++++++++++++++++++++
 net/smc/smc_cdc.h  |    1 +
 net/smc/smc_core.c |    2 +-
 3 files changed, 27 insertions(+), 1 deletion(-)

--- a/net/smc/smc_cdc.c
+++ b/net/smc/smc_cdc.c
@@ -115,6 +115,31 @@ int smc_cdc_msg_send(struct smc_connecti
 	return rc;
 }
 
+/* send a validation msg indicating the move of a conn to an other QP link */
+int smcr_cdc_msg_send_validation(struct smc_connection *conn)
+{
+	struct smc_host_cdc_msg *local = &conn->local_tx_ctrl;
+	struct smc_link *link = conn->lnk;
+	struct smc_cdc_tx_pend *pend;
+	struct smc_wr_buf *wr_buf;
+	struct smc_cdc_msg *peer;
+	int rc;
+
+	rc = smc_cdc_get_free_slot(conn, link, &wr_buf, NULL, &pend);
+	if (rc)
+		return rc;
+
+	peer = (struct smc_cdc_msg *)wr_buf;
+	peer->common.type = local->common.type;
+	peer->len = local->len;
+	peer->seqno = htons(conn->tx_cdc_seq_fin); /* seqno last compl. tx */
+	peer->token = htonl(local->token);
+	peer->prod_flags.failover_validation = 1;
+
+	rc = smc_wr_tx_send(link, (struct smc_wr_tx_pend_priv *)pend);
+	return rc;
+}
+
 static int smcr_cdc_get_slot_and_msg_send(struct smc_connection *conn)
 {
 	struct smc_cdc_tx_pend *pend;
--- a/net/smc/smc_cdc.h
+++ b/net/smc/smc_cdc.h
@@ -313,6 +313,7 @@ int smc_cdc_msg_send(struct smc_connecti
 		     struct smc_cdc_tx_pend *pend);
 int smc_cdc_get_slot_and_msg_send(struct smc_connection *conn);
 int smcd_cdc_msg_send(struct smc_connection *conn);
+int smcr_cdc_msg_send_validation(struct smc_connection *conn);
 int smc_cdc_init(void) __init;
 void smcd_cdc_rx_init(struct smc_connection *conn);
 
--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c
@@ -483,7 +483,7 @@ static int smc_switch_cursor(struct smc_
 
 	if (smc->sk.sk_state != SMC_INIT &&
 	    smc->sk.sk_state != SMC_CLOSED) {
-		/* tbd: call rc = smc_cdc_get_slot_and_msg_send(conn); */
+		rc = smcr_cdc_msg_send_validation(conn);
 		if (!rc) {
 			schedule_delayed_work(&conn->tx_work, 0);
 			smc->sk.sk_data_ready(&smc->sk);