[process] Pass containing object pointer to process step() methods

Give the step() method a pointer to the containing object, rather than
a pointer to the process.  This is consistent with the operation of
interface methods, and allows a single function to serve as both an
interface method and a process step() method.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/core/hw.c

 	process_del ( &hw->process );
 }
 
-static struct interface_operation hw_xfer_operations[] = {
-	INTF_OP ( intf_close, struct hw *, hw_finished ),
-};
-
-static struct interface_descriptor hw_xfer_desc =
-	INTF_DESC ( struct hw, xfer, hw_xfer_operations );
-
-static void hw_step ( struct process *process ) {
-	struct hw *hw = container_of ( process, struct hw, process );
+static void hw_step ( struct hw *hw ) {
 	int rc;
 
 	if ( xfer_window ( &hw->xfer ) ) {
 	}
 }
 
+static struct interface_operation hw_xfer_operations[] = {
+	INTF_OP ( intf_close, struct hw *, hw_finished ),
+};
+
+static struct interface_descriptor hw_xfer_desc =
+	INTF_DESC ( struct hw, xfer, hw_xfer_operations );
+
+static struct process_descriptor hw_process_desc =
+	PROC_DESC ( struct hw, process, hw_step );
+
 static int hw_open ( struct interface *xfer, struct uri *uri __unused ) {
 	struct hw *hw;
 
 		return -ENOMEM;
 	ref_init ( &hw->refcnt, NULL );
 	intf_init ( &hw->xfer, &hw_xfer_desc, &hw->refcnt );
-	process_init ( &hw->process, hw_step, &hw->refcnt );
+	process_init ( &hw->process, &hw_process_desc, &hw->refcnt );
 
 	/* Attach parent interface, mortalise self, and return */
 	intf_plug_plug ( &hw->xfer, xfer );

src/core/process.c

 /** Process run queue */
 static LIST_HEAD ( run_queue );
 
+/**
+ * Get pointer to object containing process
+ *
+ * @v process		Process
+ * @ret object		Containing object
+ */
+void * process_object ( struct process *process ) {
+	return ( ( ( void * ) process ) - process->desc->offset );
+}
+
 /**
  * Add process to process list
  *
  */
 void process_add ( struct process *process ) {
 	if ( ! process_running ( process ) ) {
-		DBGC ( process, "PROCESS %p (%p) starting\n",
-		       process, process->step );
+		DBGC ( PROC_COL ( process ), "PROCESS " PROC_FMT
+		       " starting\n", PROC_DBG ( process ) );
 		ref_get ( process->refcnt );
 		list_add_tail ( &process->list, &run_queue );
 	} else {
-		DBGC ( process, "PROCESS %p (%p) already started\n",
-		       process, process->step );
+		DBGC ( PROC_COL ( process ), "PROCESS " PROC_FMT
+		       " already started\n", PROC_DBG ( process ) );
 	}
 }
 
  */
 void process_del ( struct process *process ) {
 	if ( process_running ( process ) ) {
-		DBGC ( process, "PROCESS %p (%p) stopping\n",
-		       process, process->step );
+		DBGC ( PROC_COL ( process ), "PROCESS " PROC_FMT
+		       " stopping\n", PROC_DBG ( process ) );
 		list_del ( &process->list );
 		INIT_LIST_HEAD ( &process->list );
 		ref_put ( process->refcnt );
 	} else {
-		DBGC ( process, "PROCESS %p (%p) already stopped\n",
-		       process, process->step );
+		DBGC ( PROC_COL ( process ), "PROCESS " PROC_FMT
+		       " already stopped\n", PROC_DBG ( process ) );
 	}
 }
 
  */
 void step ( void ) {
 	struct process *process;
+	struct process_descriptor *desc;
+	void *object;
 
 	if ( ( process = list_first_entry ( &run_queue, struct process,
 					    list ) ) ) {
+		ref_get ( process->refcnt ); /* Inhibit destruction mid-step */
+		desc = process->desc;
+		object = process_object ( process );
 		list_del ( &process->list );
 		list_add_tail ( &process->list, &run_queue );
-		ref_get ( process->refcnt ); /* Inhibit destruction mid-step */
-		DBGC2 ( process, "PROCESS %p (%p) executing\n",
-			process, process->step );
-		process->step ( process );
-		DBGC2 ( process, "PROCESS %p (%p) finished executing\n",
-			process, process->step );
+		DBGC2 ( PROC_COL ( process ), "PROCESS " PROC_FMT
+			" executing\n", PROC_DBG ( process ) );
+		desc->step ( object );
+		DBGC2 ( PROC_COL ( process ), "PROCESS " PROC_FMT
+			" finished executing\n", PROC_DBG ( process ) );
 		ref_put ( process->refcnt ); /* Allow destruction */
 	}
 }

src/core/resolv.c

 	int rc;
 };
 
-static void numeric_step ( struct process *process ) {
-	struct numeric_resolv *numeric =
-		container_of ( process, struct numeric_resolv, process );
+static void numeric_step ( struct numeric_resolv *numeric ) {
 
-	process_del ( process );
+	process_del ( &numeric->process );
 	if ( numeric->rc == 0 )
 		resolv_done ( &numeric->resolv, &numeric->sa );
 	intf_shutdown ( &numeric->resolv, numeric->rc );
 }
 
+static struct process_descriptor numeric_process_desc =
+	PROC_DESC ( struct numeric_resolv, process, numeric_step );
+
 static int numeric_resolv ( struct interface *resolv,
 			    const char *name, struct sockaddr *sa ) {
 	struct numeric_resolv *numeric;
 		return -ENOMEM;
 	ref_init ( &numeric->refcnt, NULL );
 	intf_init ( &numeric->resolv, &null_intf_desc, &numeric->refcnt );
-	process_init ( &numeric->process, numeric_step, &numeric->refcnt );
+	process_init ( &numeric->process, &numeric_process_desc,
+		       &numeric->refcnt );
 	memcpy ( &numeric->sa, sa, sizeof ( numeric->sa ) );
 
 	DBGC ( numeric, "NUMERIC %p attempting to resolve \"%s\"\n",

src/drivers/block/scsi.c

 /**
  * SCSI TEST UNIT READY process
  *
- * @v process		Process
+ * @v scsidev		SCSI device
  */
-static void scsidev_step ( struct process *process ) {
-	struct scsi_device *scsidev =
-		container_of ( process, struct scsi_device, process );
+static void scsidev_step ( struct scsi_device *scsidev ) {
 	int rc;
 
 	/* Wait until underlying SCSI device is ready */
 	INTF_DESC_PASSTHRU ( struct scsi_device, scsi,
 			     scsidev_scsi_op, block );
 
+/** SCSI device process descriptor */
+static struct process_descriptor scsidev_process_desc =
+	PROC_DESC ( struct scsi_device, process, scsidev_step );
+
 /**
  * Open SCSI device
  *
 	intf_init ( &scsidev->block, &scsidev_block_desc, &scsidev->refcnt );
 	intf_init ( &scsidev->scsi, &scsidev_scsi_desc, &scsidev->refcnt );
 	intf_init ( &scsidev->ready, &scsidev_ready_desc, &scsidev->refcnt );
-	process_init ( &scsidev->process, scsidev_step, &scsidev->refcnt );
+	process_init ( &scsidev->process, &scsidev_process_desc,
+		       &scsidev->refcnt );
 	INIT_LIST_HEAD ( &scsidev->cmds );
 	memcpy ( &scsidev->lun, lun, sizeof ( scsidev->lun ) );
 	DBGC ( scsidev, "SCSI %p created for LUN " SCSI_LUN_FORMAT "\n",

src/include/ipxe/process.h

 struct process {
 	/** List of processes */
 	struct list_head list;
+	/** Process descriptor */
+	struct process_descriptor *desc;
+	/** Reference counter
+	 *
+	 * If this process is not part of a reference-counted object,
+	 * this field may be NULL.
+	 */
+	struct refcnt *refcnt;
+};
+
+/** A process descriptor */
+struct process_descriptor {
+	/** Offset of process within containing object */
+	size_t offset;
 	/**
 	 * Single-step the process
 	 *
 	 * Returning from this method is isomorphic to yielding the
 	 * CPU to another process.
 	 */
-	void ( * step ) ( struct process *process );
-	/** Reference counter
-	 *
-	 * If this interface is not part of a reference-counted
-	 * object, this field may be NULL.
-	 */
-	struct refcnt *refcnt;
+	void ( * step ) ( void *object );
 };
 
+/**
+ * Define a process step() method
+ *
+ * @v object_type	Implementing method's expected object type
+ * @v step		Implementing method
+ * @ret step		Process step method
+ */
+#define PROC_STEP( object_type, step )					      \
+	( ( ( ( typeof ( step ) * ) NULL ) ==				      \
+	    ( ( void ( * ) ( object_type *object ) ) NULL ) ) ?		      \
+	  ( void ( * ) ( void *object ) ) step :			      \
+	  ( void ( * ) ( void *object ) ) step )
+
+/**
+ * Calculate offset of process within containing object
+ *
+ * @v object_type	Containing object data type
+ * @v name		Process name (i.e. field within object data type)
+ * @ret offset		Offset of process within containing object
+ */
+#define process_offset( object_type, name )				      \
+	( ( ( ( typeof ( ( ( object_type * ) NULL )->name ) * ) NULL )	      \
+	    == ( ( struct process * ) NULL ) )			      	      \
+	  ? offsetof ( object_type, name )				      \
+	  : offsetof ( object_type, name ) )
+
+/**
+ * Define a process descriptor
+ *
+ * @v object_type	Containing object data type
+ * @v process		Process name (i.e. field within object data type)
+ * @v step		Process' step() method
+ * @ret desc		Object interface descriptor
+ */
+#define PROC_DESC( object_type, process, _step ) {			      \
+		.offset = process_offset ( object_type, process ),	      \
+		.step = PROC_STEP ( object_type, _step ),		      \
+	}
+
+/**
+ * Define a process descriptor for a pure process
+ *
+ * A pure process is a process that does not have a containing object.
+ *
+ * @v step		Process' step() method
+ * @ret desc		Object interface descriptor
+ */
+#define PROC_DESC_PURE( _step ) {					      \
+		.offset = 0,						      \
+		.step = PROC_STEP ( struct process, _step ),		      \
+	}
+
+extern void * __attribute__ (( pure ))
+process_object ( struct process *process );
 extern void process_add ( struct process *process );
 extern void process_del ( struct process *process );
 extern void step ( void );
  * Initialise process without adding to process list
  *
  * @v process		Process
- * @v step		Process' step() method
+ * @v desc		Process descriptor
+ * @v refcnt		Containing object reference count, or NULL
  */
 static inline __attribute__ (( always_inline )) void
 process_init_stopped ( struct process *process,
-		       void ( * step ) ( struct process *process ),
+		       struct process_descriptor *desc,
 		       struct refcnt *refcnt ) {
 	INIT_LIST_HEAD ( &process->list );
-	process->step = step;
+	process->desc = desc;
 	process->refcnt = refcnt;
 }
 
  * Initialise process and add to process list
  *
  * @v process		Process
- * @v step		Process' step() method
+ * @v desc		Process descriptor
+ * @v refcnt		Containing object reference count, or NULL
  */
 static inline __attribute__ (( always_inline )) void
 process_init ( struct process *process,
-	       void ( * step ) ( struct process *process ),
+	       struct process_descriptor *desc,
 	       struct refcnt *refcnt ) {
-	process_init_stopped ( process, step, refcnt );
+	process_init_stopped ( process, desc, refcnt );
 	process_add ( process );
 }
 
  */
 #define __permanent_process __table_entry ( PERMANENT_PROCESSES, 01 )
 
+/** Define a permanent process
+ *
+ */
+#define PERMANENT_PROCESS( name, step )					      \
+struct process_descriptor name ## _desc = PROC_DESC_PURE ( step );	      \
+struct process name __permanent_process = {				      \
+	.list = LIST_HEAD_INIT ( name.list ),				      \
+	.desc = & name ## _desc,					      \
+	.refcnt = NULL,							      \
+};
+
+/**
+ * Find debugging colourisation for a process
+ *
+ * @v process		Process
+ * @ret col		Debugging colourisation
+ *
+ * Use as the first argument to DBGC() or equivalent macro.
+ */
+#define PROC_COL( process ) process_object ( process )
+
+/** printf() format string for PROC_DBG() */
+#define PROC_FMT "%p+%zx"
+
+/**
+ * printf() arguments for representing a process
+ *
+ * @v process		Process
+ * @ret args		printf() argument list corresponding to PROC_FMT
+ */
+#define PROC_DBG( process ) process_object ( process ), (process)->desc->offset
+
 #endif /* _IPXE_PROCESS_H */

src/net/80211/net80211.c

  * @defgroup net80211_assoc_ll 802.11 association handling functions
  * @{
  */
-static void net80211_step_associate ( struct process *proc );
+static void net80211_step_associate ( struct net80211_device *dev );
 static void net80211_handle_auth ( struct net80211_device *dev,
 				   struct io_buffer *iob );
 static void net80211_handle_assoc_reply ( struct net80211_device *dev,
 
 /* ---------- Driver API ---------- */
 
+/** 802.11 association process descriptor */
+static struct process_descriptor net80211_process_desc =
+	PROC_DESC ( struct net80211_device, proc_assoc,
+		    net80211_step_associate );
+
 /**
  * Allocate 802.11 device
  *
 	dev->priv = ( u8 * ) dev + sizeof ( *dev );
 	dev->op = &net80211_null_ops;
 
-	process_init_stopped ( &dev->proc_assoc, net80211_step_associate,
+	process_init_stopped ( &dev->proc_assoc, &net80211_process_desc,
 			       &netdev->refcnt );
 	INIT_LIST_HEAD ( &dev->mgmt_queue );
 	INIT_LIST_HEAD ( &dev->mgmt_info_queue );
 /**
  * Step 802.11 association process
  *
- * @v proc	Association process
+ * @v dev	802.11 device
  */
-static void net80211_step_associate ( struct process *proc )
+static void net80211_step_associate ( struct net80211_device *dev )
 {
-	struct net80211_device *dev =
-	    container_of ( proc, struct net80211_device, proc_assoc );
 	int rc = 0;
 	int status = dev->state & NET80211_STATUS_MASK;
 
 
 	dev->rctl = rc80211_init ( dev );
 
-	process_del ( proc );
+	process_del ( &dev->proc_assoc );
 
 	DBGC ( dev, "802.11 %p associated with %s (%s)\n", dev,
 	       dev->essid, eth_ntoa ( dev->bssid ) );
 	net80211_free_wlan ( dev->associating );
 	dev->associating = NULL;
 
-	process_del ( proc );
+	process_del ( &dev->proc_assoc );
 
 	DBGC ( dev, "802.11 %p association failed (state=%04x): "
 	       "%s\n", dev, dev->state, strerror ( dev->assoc_rc ) );

src/net/fcels.c

 /**
  * Fibre Channel ELS process
  *
- * @v process		Process
+ * @v els		Fibre Channel ELS transaction
  */
-static void fc_els_step ( struct process *process ) {
-	struct fc_els *els =
-		container_of ( process, struct fc_els, process );
+static void fc_els_step ( struct fc_els *els ) {
 	int xchg_id;
 	int rc;
 
 	}
 }
 
+/** Fibre Channel ELS process descriptor */
+static struct process_descriptor fc_els_process_desc =
+	PROC_DESC ( struct fc_els, process, fc_els_step );
+
 /**
  * Create ELS transaction
  *
 	ref_init ( &els->refcnt, fc_els_free );
 	intf_init ( &els->job, &fc_els_job_desc, &els->refcnt );
 	intf_init ( &els->xchg, &fc_els_xchg_desc, &els->refcnt );
-	process_init_stopped ( &els->process, fc_els_step, &els->refcnt );
+	process_init_stopped ( &els->process, &fc_els_process_desc,
+			       &els->refcnt );
 	els->port = fc_port_get ( port );
 	memcpy ( &els->port_id, port_id, sizeof ( els->port_id ) );
 	memcpy ( &els->peer_port_id, peer_port_id,

src/net/fcns.c

 /**
  * Name server query process
  *
- * @v process		Process
+ * @v query		Name server query
  */
-static void fc_ns_query_step ( struct process *process ) {
-	struct fc_ns_query *query =
-		container_of ( process, struct fc_ns_query, process );
+static void fc_ns_query_step ( struct fc_ns_query *query ) {
 	struct xfer_metadata meta;
 	struct fc_ns_gid_pn_request gid_pn;
 	int xchg_id;
 static struct interface_descriptor fc_ns_query_xchg_desc =
 	INTF_DESC ( struct fc_ns_query, xchg, fc_ns_query_xchg_op );
 
+/** Name server process descriptor */
+static struct process_descriptor fc_ns_query_process_desc =
+	PROC_DESC ( struct fc_ns_query, process, fc_ns_query_step );
+
 /**
  * Issue Fibre Channel name server query
  *
 		return -ENOMEM;
 	ref_init ( &query->refcnt, fc_ns_query_free );
 	intf_init ( &query->xchg, &fc_ns_query_xchg_desc, &query->refcnt );
-	process_init ( &query->process, fc_ns_query_step, &query->refcnt );
+	process_init ( &query->process, &fc_ns_query_process_desc,
+		       &query->refcnt );
 	query->peer = fc_peer_get ( peer );
 	query->port = fc_port_get ( port );
 	query->done = done;

src/net/fcp.c

 /**
  * Transmit FCP frame
  *
- * @v process		FCP command process
+ * @v fcpcmd		FCP command
  */
-static void fcpcmd_step ( struct process *process ) {
-	struct fcp_command *fcpcmd =
-		container_of ( process, struct fcp_command, process );
+static void fcpcmd_step ( struct fcp_command *fcpcmd ) {
 	int rc;
 
 	/* Send the current IU */
 static struct interface_descriptor fcpcmd_xchg_desc =
 	INTF_DESC_PASSTHRU ( struct fcp_command, xchg, fcpcmd_xchg_op, scsi );
 
+/** FCP command process descriptor */
+static struct process_descriptor fcpcmd_process_desc =
+	PROC_DESC ( struct fcp_command, process, fcpcmd_step );
+
 /**
  * Issue FCP SCSI command
  *
 	ref_init ( &fcpcmd->refcnt, fcpcmd_free );
 	intf_init ( &fcpcmd->scsi, &fcpcmd_scsi_desc, &fcpcmd->refcnt );
 	intf_init ( &fcpcmd->xchg, &fcpcmd_xchg_desc, &fcpcmd->refcnt );
-	process_init_stopped ( &fcpcmd->process, fcpcmd_step, &fcpcmd->refcnt );
+	process_init_stopped ( &fcpcmd->process, &fcpcmd_process_desc,
+			       &fcpcmd->refcnt );
 	fcpcmd->fcpdev = fcpdev_get ( fcpdev );
 	list_add ( &fcpcmd->list, &fcpdev->fcpcmds );
 	memcpy ( &fcpcmd->command, command, sizeof ( fcpcmd->command ) );

src/net/infiniband.c

 }
 
 /** Infiniband event queue process */
-struct process ib_process __permanent_process = {
-	.list = LIST_HEAD_INIT ( ib_process.list ),
-	.step = ib_step,
-};
+PERMANENT_PROCESS ( ib_process, ib_step );
 
 /***************************************************************************
  *

src/net/infiniband/ib_cmrc.c

 /**
  * Shut down CMRC connection gracefully
  *
- * @v process		Process
+ * @v cmrc		Communication-Managed Reliable Connection
  *
  * The Infiniband data structures are not reference-counted or
  * guarded.  It is therefore unsafe to shut them down while we may be
  * connection, ensuring that the structure is not freed before the
  * shutdown process has run.
  */
-static void ib_cmrc_shutdown ( struct process *process ) {
-	struct ib_cmrc_connection *cmrc =
-		container_of ( process, struct ib_cmrc_connection, shutdown );
+static void ib_cmrc_shutdown ( struct ib_cmrc_connection *cmrc ) {
 
 	DBGC ( cmrc, "CMRC %p shutting down\n", cmrc );
 
 static struct interface_descriptor ib_cmrc_xfer_desc =
 	INTF_DESC ( struct ib_cmrc_connection, xfer, ib_cmrc_xfer_operations );
 
+/** CMRC shutdown process descriptor */
+static struct process_descriptor ib_cmrc_shutdown_desc =
+	PROC_DESC ( struct ib_cmrc_connection, shutdown, ib_cmrc_shutdown );
+
 /**
  * Open CMRC connection
  *
 	cmrc->ibdev = ibdev;
 	memcpy ( &cmrc->dgid, dgid, sizeof ( cmrc->dgid ) );
 	memcpy ( &cmrc->service_id, service_id, sizeof ( cmrc->service_id ) );
-	process_init_stopped ( &cmrc->shutdown, ib_cmrc_shutdown,
+	process_init_stopped ( &cmrc->shutdown, &ib_cmrc_shutdown_desc,
 			       &cmrc->refcnt );
 
 	/* Open Infiniband device */

src/net/netdevice.c

 }
 
 /** Networking stack process */
-struct process net_process __permanent_process = {
-	.list = LIST_HEAD_INIT ( net_process.list ),
-	.step = net_step,
-};
+PERMANENT_PROCESS ( net_process, net_step );

src/net/retry.c

 }
 
 /** Retry timer process */
-struct process retry_process __permanent_process = {
-	.list = LIST_HEAD_INIT ( retry_process.list ),
-	.step = retry_step,
-};
+PERMANENT_PROCESS ( retry_process, retry_step );

src/net/tcp/http.c

 /**
  * HTTP process
  *
- * @v process		Process
+ * @v http		HTTP request
  */
-static void http_step ( struct process *process ) {
-	struct http_request *http =
-		container_of ( process, struct http_request, process );
+static void http_step ( struct http_request *http ) {
 	const char *host = http->uri->host;
 	const char *user = http->uri->user;
 	const char *password =
 	INTF_DESC_PASSTHRU ( struct http_request, xfer,
 			     http_xfer_operations, socket );
 
+/** HTTP process descriptor */
+static struct process_descriptor http_process_desc =
+	PROC_DESC ( struct http_request, process, http_step );
+
 /**
  * Initiate an HTTP connection, with optional filter
  *
 	intf_init ( &http->xfer, &http_xfer_desc, &http->refcnt );
        	http->uri = uri_get ( uri );
 	intf_init ( &http->socket, &http_socket_desc, &http->refcnt );
-	process_init ( &http->process, http_step, &http->refcnt );
+	process_init ( &http->process, &http_process_desc, &http->refcnt );
 
 	/* Open socket */
 	memset ( &server, 0, sizeof ( server ) );

src/net/tcp/iscsi.c

  * 
  * Constructs data to be sent for the current TX state
  */
-static void iscsi_tx_step ( struct process *process ) {
-	struct iscsi_session *iscsi =
-		container_of ( process, struct iscsi_session, process );
+static void iscsi_tx_step ( struct iscsi_session *iscsi ) {
 	struct iscsi_bhs_common *common = &iscsi->tx_bhs.common;
 	int ( * tx ) ( struct iscsi_session *iscsi );
 	enum iscsi_tx_state next_state;
 	}
 }
 
+/** iSCSI TX process descriptor */
+static struct process_descriptor iscsi_process_desc =
+	PROC_DESC ( struct iscsi_session, process, iscsi_tx_step );
+
 /**
  * Receive basic header segment of an iSCSI PDU
  *
 	intf_init ( &iscsi->control, &iscsi_control_desc, &iscsi->refcnt );
 	intf_init ( &iscsi->data, &iscsi_data_desc, &iscsi->refcnt );
 	intf_init ( &iscsi->socket, &iscsi_socket_desc, &iscsi->refcnt );
-	process_init_stopped ( &iscsi->process, iscsi_tx_step,
+	process_init_stopped ( &iscsi->process, &iscsi_process_desc,
 			       &iscsi->refcnt );
 
 	/* Parse root path */

src/net/tls.c

 /**
  * TLS TX state machine
  *
- * @v process		TLS process
+ * @v tls		TLS session
  */
-static void tls_step ( struct process *process ) {
-	struct tls_session *tls =
-		container_of ( process, struct tls_session, process );
+static void tls_step ( struct tls_session *tls ) {
 	int rc;
 
 	/* Wait for cipherstream to become ready */
 	tls_close ( tls, rc );
 }
 
+/** TLS TX process descriptor */
+static struct process_descriptor tls_process_desc =
+	PROC_DESC ( struct tls_session, process, tls_step );
+
 /******************************************************************************
  *
  * Instantiator
 	digest_init ( &md5_algorithm, tls->handshake_md5_ctx );
 	digest_init ( &sha1_algorithm, tls->handshake_sha1_ctx );
 	tls->tx_state = TLS_TX_CLIENT_HELLO;
-	process_init ( &tls->process, tls_step, &tls->refcnt );
+	process_init ( &tls->process, &tls_process_desc, &tls->refcnt );
 
 	/* Attach to parent interface, mortalise self, and return */
 	intf_plug_plug ( &tls->plainstream, xfer );