svn commit: r189574 - head/sys/kern

[Warner Losh]

Author: imp
Date: Mon Mar  9 13:20:23 2009
New Revision: 189574
URL: http://svn.freebsd.org/changeset/base/189574

Log:
  Fix a long-standing bug in newbus.  It was introduced when subclassing
  was introduced.  If you have a bus, say cardbus, that is derived from
  a base-bus (say PCI), then ordinarily all PCI drivers would attach to
  cardbus devices.  However, there had been one exception: kldload
  wouldn't work.
  
  The problem is in devclass_add_driver.  In this routine, all we did
  was call to the pci device's BUS_DRIVER_ADDED routine.  However, since
  cardbus bus instances had a different devclass, none of them were
  called.
  
  The solution is to call all subclass devclasses, recursively down the
  tree, of the class that was loaded.  Since we don't have a 'children
  class' pointer, we search the whole list of devclasses for a class
  whose parent matches.  Since just done a kldload time, this isn't as
  bad as it sounds.  In addition, we short-circuit the whole process by
  marking those classes with subclasses with a flag.  We'll likely have
  to reevaluate this method the number of devclasses with subclasses
  gets large.
  
  This means we can remove the "cardbus" lines from all the PCI drivers
  since we have no cardbus specific attach device attachments in the
  tree.
  
  # Also: minor tweak to an error message

Modified:
  head/sys/kern/subr_bus.c

Modified: head/sys/kern/subr_bus.c
==============================================================================
--- head/sys/kern/subr_bus.c	Mon Mar  9 13:12:48 2009	(r189573)
+++ head/sys/kern/subr_bus.c	Mon Mar  9 13:20:23 2009	(r189574)
@@ -82,6 +82,8 @@ struct devclass {
 	char		*name;
 	device_t	*devices;	/* array of devices indexed by unit */
 	int		maxunit;	/* size of devices array */
+	int		flags;
+#define DC_HAS_CHILDREN		1
 
 	struct sysctl_ctx_list sysctl_ctx;
 	struct sysctl_oid *sysctl_tree;
@@ -813,6 +815,7 @@ devclass_find_internal(const char *class
 	if (parentname && dc && !dc->parent &&
 	    strcmp(classname, parentname) != 0) {
 		dc->parent = devclass_find_internal(parentname, NULL, FALSE);
+		dc->parent->flags |= DC_HAS_CHILDREN;
 	}
 
 	return (dc);
@@ -846,6 +849,52 @@ devclass_find(const char *classname)
 	return (devclass_find_internal(classname, NULL, FALSE));
 }
 
+	
+/**
+ * @brief Register that a device driver has been added to a devclass
+ *
+ * Register that a device driver has been added to a devclass.  This
+ * is called by devclass_add_driver to accomplish the recursive
+ * notification of all the children classes of dc, as well as dc.
+ * Each layer will have BUS_DRIVER_ADDED() called for all instances of
+ * the devclass.  We do a full search here of the devclass list at
+ * each iteration level to save storing children-lists in the devclass
+ * structure.  If we ever move beyond a few dozen devices doing this,
+ * we may need to reevaluate...
+ *
+ * @param dc		the devclass to edit
+ * @param driver	the driver that was just added
+ */
+static void
+devclass_driver_added(devclass_t dc, driver_t *driver)
+{
+	int i;
+	devclass_t parent;
+
+	/*
+	 * Call BUS_DRIVER_ADDED for any existing busses in this class.
+	 */
+	for (i = 0; i < dc->maxunit; i++)
+		if (dc->devices[i])
+			BUS_DRIVER_ADDED(dc->devices[i], driver);
+
+	/*
+	 * Walk through the children classes.  Since we only keep a
+	 * single parent pointer around, we walk the entire list of
+	 * devclasses looking for children.  We set the
+	 * DC_HAS_CHILDREN flag when a child devclass is created on
+	 * the parent, so we only walk thoe list for those devclasses
+	 * that have children.
+	 */
+	if (!(dc->flags & DC_HAS_CHILDREN))
+		return;
+	parent = dc;
+	TAILQ_FOREACH(dc, &devclasses, link) {
+		if (dc->parent == parent)
+			devclass_driver_added(dc, driver);
+	}
+}
+
 /**
  * @brief Add a device driver to a device class
  *
@@ -861,7 +910,6 @@ int
 devclass_add_driver(devclass_t dc, driver_t *driver)
 {
 	driverlink_t dl;
-	int i;
 
 	PDEBUG(("%s", DRIVERNAME(driver)));
 
@@ -886,13 +934,7 @@ devclass_add_driver(devclass_t dc, drive
 	TAILQ_INSERT_TAIL(&dc->drivers, dl, link);
 	driver->refs++;		/* XXX: kobj_mtx */
 
-	/*
-	 * Call BUS_DRIVER_ADDED for any existing busses in this class.
-	 */
-	for (i = 0; i < dc->maxunit; i++)
-		if (dc->devices[i])
-			BUS_DRIVER_ADDED(dc->devices[i], driver);
-
+	devclass_driver_added(dc, driver);
 	bus_data_generation_update();
 	return (0);
 }
@@ -1758,7 +1800,9 @@ device_probe_child(device_t dev, device_
 			device_set_driver(child, dl->driver);
 			if (!hasclass) {
 				if (device_set_devclass(child, dl->driver->name)) {
-					PDEBUG(("Unable to set device class"));
+					printf("driver bug: Unable to set devclass (devname: %s)\n",
+					    (child ? device_get_name(child) :
+						"no device"));
 					device_set_driver(child, NULL);
 					continue;
 				}