From d4e519a36a0233b7206a8879f41929e3929c5279 Mon Sep 17 00:00:00 2001
From: imp <imp@FreeBSD.org>
Date: Tue, 5 Dec 2006 06:11:10 +0000
Subject: More properly cleanup the iicbus child when deleting it.

These are from patches by John Wehle, but the commentary has been
updated by me.

Obtained from: ports/multimedia/pvr250, indirectly
---
 sys/dev/iicbus/iicbb.c | 33 +++++++++++++++++++++++++++------
 1 file changed, 27 insertions(+), 6 deletions(-)

(limited to 'sys/dev/iicbus/iicbb.c')

diff --git a/sys/dev/iicbus/iicbb.c b/sys/dev/iicbus/iicbb.c
index 6c70478..7fa80c1 100644
--- a/sys/dev/iicbus/iicbb.c
+++ b/sys/dev/iicbus/iicbb.c
@@ -63,10 +63,11 @@ struct iicbb_softc {
 	device_t iicbus;
 };
 
-static int iicbb_probe(device_t);
 static int iicbb_attach(device_t);
+static void iicbb_child_detached(device_t, device_t);
 static int iicbb_detach(device_t);
 static int iicbb_print_child(device_t, device_t);
+static int iicbb_probe(device_t);
 
 static int iicbb_callback(device_t, int, caddr_t);
 static int iicbb_start(device_t, u_char, int);
@@ -82,6 +83,7 @@ static device_method_t iicbb_methods[] = {
 	DEVMETHOD(device_detach,	iicbb_detach),
 
 	/* bus interface */
+	DEVMETHOD(bus_child_detached,	iicbb_child_detached),
 	DEVMETHOD(bus_print_child,	iicbb_print_child),
 
 	/* iicbus interface */
@@ -129,15 +131,34 @@ static int
 iicbb_detach(device_t dev)
 {
 	struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
-
-	if (sc->iicbus) {
-		bus_generic_detach(dev);
-		device_delete_child(dev, sc->iicbus);
-	}
+	device_t child;
+
+	/*
+	 * We need to save child because the detach indirectly causes
+	 * sc->iicbus to be zeroed.  Since we added the device
+	 * unconditionally in iicbb_attach, we need to make sure we
+	 * delete it here.  See iicbb_child_detached.  We need that
+	 * callback in case newbus detached our children w/o detaching
+	 * us (say iicbus is a module and unloaded w/o iicbb being
+	 * unloaded).
+	 */
+	child = sc->iicbus;
+	bus_generic_detach(dev);
+	if (child)
+		device_delete_child(dev, child);
 
 	return (0);
 }
 
+static void
+iicbb_child_detached( device_t dev, device_t child )
+{
+	struct iicbb_softc *sc = (struct iicbb_softc *)device_get_softc(dev);
+
+	if (child == sc->iicbus)
+		sc->iicbus = NULL;
+}
+
 static int
 iicbb_print_child(device_t bus, device_t dev)
 {
-- 
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