From 267ec43593e9197b42f841ebb466538079bd06b8 Mon Sep 17 00:00:00 2001 From: John Baldwin Date: Fri, 20 Jan 2006 21:59:13 +0000 Subject: [PATCH] When loading a driver that is a subclass of another driver don't set the devclass's parent pointer if the two drivers share the same devclass. This can happen if the drivers use the same new-bus name. For example, we currently have 3 drivers that use the name "pci": the generic PCI bus driver, the ACPI PCI bus driver, and the OpenFirmware PCI bus driver. If the ACPI PCI bus driver was defined as a subclass of the generic PCI bus driver, then without this check the "pci" devclass would point to itself as its parent and device_probe_child() would spin forever when it encountered the first PCI device that did have a matching driver. Reviewed by: dfr, imp, new-bus@ --- sys/kern/subr_bus.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/sys/kern/subr_bus.c b/sys/kern/subr_bus.c index 7f7bb934374..b19be5417f3 100644 --- a/sys/kern/subr_bus.c +++ b/sys/kern/subr_bus.c @@ -781,7 +781,17 @@ devclass_find_internal(const char *classname, const char *parentname, bus_data_generation_update(); } - if (parentname && dc && !dc->parent) { + + /* + * 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, 0, FALSE); }