scst: Make constant-success helper results explicit

Make netlink registration and the optional mode-page path check return
void and remove callers' unreachable error checks. Neither helper can
fail its caller. Preserve success ACKs, the disabled mode-page fallback
and all reachable error paths.

Return explicit success after the checked portal-address ioctl. Source
review also found that scst_cm_ext_copy_exec() never changes its result
variable; return SCST_EXEC_COMPLETED directly while preserving command
completion callbacks and error paths.

Cppcheck reports knownConditionTrueFalse:
  Condition 'err' is always false.

Cppcheck reports identicalConditionAfterEarlyExit:
  Identical condition and return expression 'ret', return value is
  always 0

iscsi-scst/kernel/event.c

@@ -49,7 +49,7 @@ static inline void netlink_ack_backport(struct sk_buff *in_skb,
 static struct sock *nl;
 static u32 iscsid_pid;
 
-static int event_recv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
+static void event_recv_msg(struct sk_buff *skb)
 {
 	u32 pid;
 
@@ -57,13 +57,10 @@ static int event_recv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 	WARN_ON(pid == 0);
 
 	iscsid_pid = pid;
-
-	return 0;
 }
 
 static void event_recv_skb(struct sk_buff *skb)
 {
-	int err;
 	struct nlmsghdr	*nlh;
 	u32 rlen;
 
@@ -74,10 +71,8 @@ static void event_recv_skb(struct sk_buff *skb)
 		rlen = NLMSG_ALIGN(nlh->nlmsg_len);
 		if (rlen > skb->len)
 			rlen = skb->len;
-		err = event_recv_msg(skb, nlh);
-		if (err)
-			netlink_ack(skb, nlh, -err, NULL);
-		else if (nlh->nlmsg_flags & NLM_F_ACK)
+		event_recv_msg(skb);
+		if (nlh->nlmsg_flags & NLM_F_ACK)
 			netlink_ack(skb, nlh, 0, NULL);
 		skb_pull(skb, rlen);
 	}

iscsi-scst/usr/iscsi_scstd.c

@@ -319,7 +319,7 @@ static int iser_getsockname(int fd, struct sockaddr *name, socklen_t *namelen)
 	memcpy(name, &addr.addr, addr.addr_len);
 	*namelen = addr.addr_len;
 
-	return ret;
+	return 0;
 }
 
 static int iser_is_discovery(int fd)

scst/src/dev_handlers/scst_vdisk_main.c

@@ -9864,7 +9864,7 @@ static void init_ops(vdisk_op_fn *ops, int count)
 			ops[i] = vdisk_invalid_opcode;
 }
 
-static int __init vdev_check_mode_pages_path(void)
+static void __init vdev_check_mode_pages_path(void)
 {
 	int res;
 	struct path path;
@@ -9880,10 +9880,7 @@ static int __init vdev_check_mode_pages_path(void)
 		vdev_saved_mode_pages_enabled = false;
 	}
 
-	res = 0; /* always succeed */
-
-	TRACE_EXIT_RES(res);
-	return res;
+	TRACE_EXIT();
 }
 
 #define SHARED_OPS							\
@@ -10005,9 +10002,7 @@ static int __init init_scst_vdisk_driver(void)
 	init_ops(blockio_ops, ARRAY_SIZE(blockio_ops));
 	init_ops(nullio_ops, ARRAY_SIZE(nullio_ops));
 
-	res = vdev_check_mode_pages_path();
-	if (res != 0)
-		goto out;
+	vdev_check_mode_pages_path();
 
 	vdisk_cmd_param_cachep = KMEM_CACHE(vdisk_cmd_params,
 					    SCST_SLAB_FLAGS | SLAB_HWCACHE_ALIGN);

scst/src/scst_copy_mgr.c

@@ -1584,7 +1584,6 @@ out:
 
 enum scst_exec_res scst_cm_ext_copy_exec(struct scst_cmd *ec_cmd)
 {
-	enum scst_exec_res res = SCST_EXEC_COMPLETED;
 	int rc;
 	struct scst_cm_ec_cmd_priv *priv = ec_cmd->cmd_data_descriptors;
 
@@ -1606,7 +1605,7 @@ enum scst_exec_res scst_cm_ext_copy_exec(struct scst_cmd *ec_cmd)
 
 out:
 	TRACE_EXIT();
-	return res;
+	return SCST_EXEC_COMPLETED;
 
 out_local_done:
 	ec_cmd->completed = 1; /* for success */