[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

@@ -26,15 +26,7 @@ static void hw_finished ( struct hw *hw, int rc ) {
 	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 ) ) {
@@ -43,6 +35,16 @@ static void hw_step ( struct process *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 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;
 
@@ -52,7 +54,7 @@ static int hw_open ( struct interface *xfer, struct uri *uri __unused ) {
 		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

@@ -33,6 +33,16 @@ FILE_LICENCE ( GPL2_OR_LATER );
 /** 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
  *
@@ -43,13 +53,13 @@ static LIST_HEAD ( run_queue );
  */
 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 ) );
 	}
 }
 
@@ -63,14 +73,14 @@ void process_add ( struct process *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 ) );
 	}
 }
 
@@ -82,17 +92,21 @@ void process_del ( struct process *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

@@ -86,16 +86,17 @@ struct numeric_resolv {
 	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;
@@ -107,7 +108,8 @@ static int numeric_resolv ( struct interface *resolv,
 		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",