netdev - [PATCH net-next 2/2] net/smc: improve peer ID in CLC decline for SMC-R

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Message-Id: <20200224235901.304311-3-ndev@hwipl.net>
Date:   Tue, 25 Feb 2020 00:59:01 +0100
From:   Hans Wippel <ndev@...pl.net>
To:     kgraul@...ux.ibm.com, ubraun@...ux.ibm.com, davem@...emloft.net
Cc:     netdev@...r.kernel.org, Hans Wippel <ndev@...pl.net>
Subject: [PATCH net-next 2/2] net/smc: improve peer ID in CLC decline for SMC-R

According to RFC 7609, all CLC messages contain a peer ID that consists
of a unique instance ID and the MAC address of one of the host's RoCE
devices. But if a SMC-R connection cannot be established, e.g., because
no matching pnet table entry is found, the current implementation uses a
zero value in the CLC decline message although the host's peer ID is set
to a proper value.

If no RoCE and no ISM device is usable for a connection, there is no LGR
and the LGR check in smc_clc_send_decline() prevents that the peer ID is
copied into the CLC decline message for both SMC-D and SMC-R. So, this
patch modifies the check to also accept the case of no LGR. Also, only a
valid peer ID is copied into the decline message.

Signed-off-by: Hans Wippel <ndev@...pl.net>
---
 net/smc/smc_clc.c | 9 ++++++---
 net/smc/smc_ib.h  | 1 +
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/net/smc/smc_clc.c b/net/smc/smc_clc.c
index 3e16b887cfcf..e2d3b5b95632 100644
--- a/net/smc/smc_clc.c
+++ b/net/smc/smc_clc.c
@@ -372,9 +372,12 @@ int smc_clc_send_decline(struct smc_sock *smc, u32 peer_diag_info)
 	dclc.hdr.length = htons(sizeof(struct smc_clc_msg_decline));
 	dclc.hdr.version = SMC_CLC_V1;
 	dclc.hdr.flag = (peer_diag_info == SMC_CLC_DECL_SYNCERR) ? 1 : 0;
-	if (smc->conn.lgr && !smc->conn.lgr->is_smcd)
-		memcpy(dclc.id_for_peer, local_systemid,
-		       sizeof(local_systemid));
+	if (!smc->conn.lgr || !smc->conn.lgr->is_smcd) {
+		if (smc_ib_is_valid_local_systemid()) {
+			memcpy(dclc.id_for_peer, local_systemid,
+			       sizeof(local_systemid));
+		}
+	}
 	dclc.peer_diagnosis = htonl(peer_diag_info);
 	memcpy(dclc.trl.eyecatcher, SMC_EYECATCHER, sizeof(SMC_EYECATCHER));
 
diff --git a/net/smc/smc_ib.h b/net/smc/smc_ib.h
index 255db87547d3..5c2b115d36da 100644
--- a/net/smc/smc_ib.h
+++ b/net/smc/smc_ib.h
@@ -84,4 +84,5 @@ void smc_ib_sync_sg_for_device(struct smc_ib_device *smcibdev,
 			       enum dma_data_direction data_direction);
 int smc_ib_determine_gid(struct smc_ib_device *smcibdev, u8 ibport,
 			 unsigned short vlan_id, u8 gid[], u8 *sgid_index);
+bool smc_ib_is_valid_local_systemid(void);
 #endif
-- 
2.25.1