Function devclass_find_internal

freebsd/kern/subr_bus.c:973–1018

* @internal * @brief Find or create a device class * * If a device class with the name @p classname exists, return it, * otherwise if @p create is non-zero create and return a new device * class. * * If @p parentname is non-NULL, the parent of the devclass is set to * the devclass of that name. * * @param classname the devclass name to find or create * @param parentname the parent devcl

 * @param create	non-zero to create a devclass
 */
static devclass_t
devclass_find_internal(const char *classname, const char *parentname,
		       int create)
{
	devclass_t dc;

	PDEBUG(("looking for %s", classname));
	if (!classname)
		return (NULL);

	TAILQ_FOREACH(dc, &devclasses, link) {
		if (!strcmp(dc->name, classname))
			break;
	}

	if (create && !dc) {
		PDEBUG(("creating %s", classname));
		dc = malloc(sizeof(struct devclass) + strlen(classname) + 1,
		    M_BUS, M_NOWAIT | M_ZERO);
		if (!dc)
			return (NULL);
		dc->parent = NULL;
		dc->name = (char*) (dc + 1);
		strcpy(dc->name, classname);
		TAILQ_INIT(&dc->drivers);
		TAILQ_INSERT_TAIL(&devclasses, dc, link);

		bus_data_generation_update();
	}

	/*
	 * If a parent class is specified, then set that as our parent so
	 * that this devclass will support drivers for the parent class as
	 * well.  If the parent class has the same name don't do this though
	 * as it creates a cycle that can trigger an infinite loop in
	 * device_probe_child() if a device exists for which there is no
	 * suitable driver.
	 */
	if (parentname && dc && !dc->parent &&
	    strcmp(classname, parentname) != 0) {
		dc->parent = devclass_find_internal(parentname, NULL, TRUE);
		dc->parent->flags |= DC_HAS_CHILDREN;
	}

	return (dc);
}

/**
 * @brief Create a device class