net/smc: improve smc_listen_work reason codes

Rework smc_listen_work() to provide improved reason codes when an
SMC connection is declined. This allows better debugging on user side.
This also adds 3 more detailed reason codes in smc_clc.h to indicate
what type of device was not found (ism or rdma or both), or if ism
cannot talk to the peer.
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/smc/af_smc.c

@@ -503,8 +503,8 @@ static int smc_find_rdma_device(struct smc_sock *smc, struct smc_init_info *ini)
 	 * used for the internal TCP socket
 	 */
 	smc_pnet_find_roce_resource(smc->clcsock->sk, ini);
-	if (!(ini->ib_dev))
-		return SMC_CLC_DECL_CNFERR; /* configuration error */
+	if (!ini->ib_dev)
+		return SMC_CLC_DECL_NOSMCRDEV;
 	return 0;
 }
 
@@ -515,7 +515,7 @@ static int smc_find_ism_device(struct smc_sock *smc, struct smc_init_info *ini)
 	/* Find ISM device with same PNETID as connecting interface  */
 	smc_pnet_find_ism_resource(smc->clcsock->sk, ini);
 	if (!ini->ism_dev)
-		return SMC_CLC_DECL_CNFERR; /* configuration error */
+		return SMC_CLC_DECL_NOSMCDDEV;
 	return 0;
 }
 
@@ -1155,7 +1155,7 @@ static int smc_listen_ism_init(struct smc_sock *new_smc,
 		if (*local_contact == SMC_FIRST_CONTACT)
 			smc_lgr_forget(new_smc->conn.lgr);
 		smc_conn_free(&new_smc->conn);
-		return SMC_CLC_DECL_CNFERR;
+		return SMC_CLC_DECL_SMCDNOTALK;
 	}
 
 	/* Create send and receive buffers */
@@ -1249,28 +1249,24 @@ static void smc_listen_work(struct work_struct *work)
 	pclc = (struct smc_clc_msg_proposal *)&buf;
 	rc = smc_clc_wait_msg(new_smc, pclc, SMC_CLC_MAX_LEN,
 			      SMC_CLC_PROPOSAL, CLC_WAIT_TIME);
-	if (rc) {
-		smc_listen_decline(new_smc, rc, 0);
-		return;
-	}
+	if (rc)
+		goto out_decl;
 
 	/* IPSec connections opt out of SMC-R optimizations */
 	if (using_ipsec(new_smc)) {
-		smc_listen_decline(new_smc, SMC_CLC_DECL_IPSEC, 0);
-		return;
+		rc = SMC_CLC_DECL_IPSEC;
+		goto out_decl;
 	}
 
 	/* check for matching IP prefix and subnet length */
 	rc = smc_listen_prfx_check(new_smc, pclc);
-	if (rc) {
-		smc_listen_decline(new_smc, rc, 0);
-		return;
-	}
+	if (rc)
+		goto out_decl;
 
 	/* get vlan id from IP device */
 	if (smc_vlan_by_tcpsk(new_smc->clcsock, &ini)) {
-		smc_listen_decline(new_smc, SMC_CLC_DECL_GETVLANERR, 0);
-		return;
+		rc = SMC_CLC_DECL_GETVLANERR;
+		goto out_decl;
 	}
 
 	mutex_lock(&smc_server_lgr_pending);
@@ -1278,41 +1274,45 @@ static void smc_listen_work(struct work_struct *work)
 	smc_rx_init(new_smc);
 	smc_tx_init(new_smc);
 
-	/* prepare ISM check */
-	ini.is_smcd = true;
 	/* check if ISM is available */
-	if ((pclc->hdr.path == SMC_TYPE_D || pclc->hdr.path == SMC_TYPE_B) &&
-	    !smc_find_ism_device(new_smc, &ini) &&
-	    !smc_listen_ism_init(new_smc, pclc, &ini, &local_contact)) {
-		ism_supported = true;
-	} else {
+	if (pclc->hdr.path == SMC_TYPE_D || pclc->hdr.path == SMC_TYPE_B) {
+		ini.is_smcd = true; /* prepare ISM check */
+		rc = smc_find_ism_device(new_smc, &ini);
+		if (!rc)
+			rc = smc_listen_ism_init(new_smc, pclc, &ini,
+						 &local_contact);
+		if (!rc)
+			ism_supported = true;
+		else if (pclc->hdr.path == SMC_TYPE_D)
+			goto out_unlock; /* skip RDMA and decline */
+	}
+
+	/* check if RDMA is available */
+	if (!ism_supported) { /* SMC_TYPE_R or SMC_TYPE_B */
 		/* prepare RDMA check */
 		memset(&ini, 0, sizeof(ini));
 		ini.is_smcd = false;
 		ini.ib_lcl = &pclc->lcl;
-	}
-
-	/* check if RDMA is available */
-	if (!ism_supported &&
-	    ((pclc->hdr.path != SMC_TYPE_R && pclc->hdr.path != SMC_TYPE_B) ||
-	     smc_vlan_by_tcpsk(new_smc->clcsock, &ini) ||
-	     smc_find_rdma_device(new_smc, &ini) ||
-	     smc_listen_rdma_init(new_smc, &ini, &local_contact) ||
-	     smc_listen_rdma_reg(new_smc, local_contact))) {
-		/* SMC not supported, decline */
-		mutex_unlock(&smc_server_lgr_pending);
-		smc_listen_decline(new_smc, SMC_CLC_DECL_MODEUNSUPP,
-				   local_contact);
-		return;
+		rc = smc_find_rdma_device(new_smc, &ini);
+		if (rc) {
+			/* no RDMA device found */
+			if (pclc->hdr.path == SMC_TYPE_B)
+				/* neither ISM nor RDMA device found */
+				rc = SMC_CLC_DECL_NOSMCDEV;
+			goto out_unlock;
+		}
+		rc = smc_listen_rdma_init(new_smc, &ini, &local_contact);
+		if (rc)
+			goto out_unlock;
+		rc = smc_listen_rdma_reg(new_smc, local_contact);
+		if (rc)
+			goto out_unlock;
 	}
 
 	/* send SMC Accept CLC message */
 	rc = smc_clc_send_accept(new_smc, local_contact);
-	if (rc) {
-		mutex_unlock(&smc_server_lgr_pending);
-		smc_listen_decline(new_smc, rc, local_contact);
-		return;
-	}
+	if (rc)
+		goto out_unlock;
 
 	/* SMC-D does not need this lock any more */
 	if (ism_supported)
@@ -1323,9 +1323,8 @@ static void smc_listen_work(struct work_struct *work)
 			      SMC_CLC_CONFIRM, CLC_WAIT_TIME);
 	if (rc) {
 		if (!ism_supported)
-			mutex_unlock(&smc_server_lgr_pending);
-		smc_listen_decline(new_smc, rc, local_contact);
-		return;
+			goto out_unlock;
+		goto out_decl;
 	}
 
 	/* finish worker */
@@ -1337,6 +1336,12 @@ static void smc_listen_work(struct work_struct *work)
 	}
 	smc_conn_save_peer_info(new_smc, &cclc);
 	smc_listen_out_connected(new_smc);
+	return;
+
+out_unlock:
+	mutex_unlock(&smc_server_lgr_pending);
+out_decl:
+	smc_listen_decline(new_smc, rc, local_contact);
 }
 
 static void smc_tcp_listen_work(struct work_struct *work)

net/smc/smc_clc.h

@@ -34,7 +34,10 @@
 #define SMC_CLC_DECL_CNFERR	0x03000000  /* configuration error            */
 #define SMC_CLC_DECL_PEERNOSMC	0x03010000  /* peer did not indicate SMC      */
 #define SMC_CLC_DECL_IPSEC	0x03020000  /* IPsec usage		      */
-#define SMC_CLC_DECL_NOSMCDEV	0x03030000  /* no SMC device found	      */
+#define SMC_CLC_DECL_NOSMCDEV	0x03030000  /* no SMC device found (R or D)   */
+#define SMC_CLC_DECL_NOSMCDDEV	0x03030001  /* no SMC-D device found	      */
+#define SMC_CLC_DECL_NOSMCRDEV	0x03030002  /* no SMC-R device found	      */
+#define SMC_CLC_DECL_SMCDNOTALK	0x03030003  /* SMC-D dev can't talk to peer   */
 #define SMC_CLC_DECL_MODEUNSUPP	0x03040000  /* smc modes do not match (R or D)*/
 #define SMC_CLC_DECL_RMBE_EC	0x03050000  /* peer has eyecatcher in RMBE    */
 #define SMC_CLC_DECL_OPTUNSUPP	0x03060000  /* fastopen sockopt not supported */