Guard against buggy PCI bridges

* panic on pci controller init failure. No reason to continue just to crash later on.
* guard against buggy or misconfigured bridges (like the VIA Apollo MVP3 in my K6-2)
by limiting the recursion depth in FixupDevices and DiscoverBus.

src/add-ons/kernel/bus_managers/pci/pci.cpp

@@ -469,6 +469,7 @@ pci_init(void)
 
 	if (pci_controller_init() != B_OK) {
 		TRACE(("PCI: pci_controller_init failed\n"));
+		panic("PCI: pci_controller_init failed\n");
 		return B_ERROR;
 	}
 
@@ -830,6 +831,15 @@ PCI::_FixupDevices(int domain, uint8 bus)
 	FLOW("PCI: FixupDevices domain %u, bus %u\n", domain, bus);
 
 	int maxBusDevices = _GetDomainData(domain)->max_bus_devices;
+	static int recursed = 0;
+
+	if (recursed++ > 10) {
+		// guard against buggy chipsets
+		// XXX: is there any official limit ?
+		dprintf("PCI: FixupDevices: too many recursions (buggy chipset?)\n");
+		recursed--;
+		return;
+	}
 
 	for (int dev = 0; dev < maxBusDevices; dev++) {
 		uint16 vendorId = ReadConfig(domain, bus, dev, 0, PCI_vendor_id, 2);
@@ -857,9 +867,12 @@ PCI::_FixupDevices(int domain, uint8 bus)
 			int busBehindBridge = ReadConfig(domain, bus, dev, function,
 				PCI_secondary_bus, 1);
 
+			TRACE(("PCI: FixupDevices: checking bus %d behind %04x:%04x\n",
+				busBehindBridge, vendorId, deviceId));
 			_FixupDevices(domain, busBehindBridge);
 		}
 	}
+	recursed--;
 }
 
 
@@ -981,6 +994,15 @@ PCI::_DiscoverBus(PCIBus *bus)
 	FLOW("PCI: DiscoverBus, domain %u, bus %u\n", bus->domain, bus->bus);
 
 	int maxBusDevices = _GetDomainData(bus->domain)->max_bus_devices;
+	static int recursed = 0;
+
+	if (recursed++ > 10) {
+		// guard against buggy chipsets
+		// XXX: is there any official limit ?
+		dprintf("PCI: DiscoverBus: too many recursions (buggy chipset?)\n");
+		recursed--;
+		return;
+	}
 
 	for (int dev = 0; dev < maxBusDevices; dev++) {
 		uint16 vendorID = ReadConfig(bus->domain, bus->bus, dev, 0,
@@ -995,6 +1017,7 @@ PCI::_DiscoverBus(PCIBus *bus)
 
 	if (bus->next)
 		_DiscoverBus(bus->next);
+	recursed--;
 }