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5ef753ae43
When hot-adding devices we rely on the hotplug driver to create pci_dn's for the devices under the hotplug slot. Converse, when hot-removing the driver will remove the pci_dn's that it created. This is a problem because the pci_dev is still live until it's refcount drops to zero. This can happen if the driver is slow to tear down it's internal state. Ideally, the driver would not attempt to perform any config accesses to the device once it's been marked as removed, but sometimes it happens. As a result, we might attempt to access the pci_dn for a device that has been torn down and the kernel may crash as a result. To fix this, don't free the pci_dn unless the corresponding pci_dev has been released. If the pci_dev is still live, then we mark the pci_dn with a flag that indicates the pci_dev's release function should free it. Signed-off-by: Oliver O'Halloran <oohall@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20190903101605.2890-3-oohall@gmail.com
154 lines
4.2 KiB
C
154 lines
4.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Derived from "arch/powerpc/platforms/pseries/pci_dlpar.c"
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*
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* Copyright (C) 2003 Linda Xie <lxie@us.ibm.com>
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* Copyright (C) 2005 International Business Machines
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*
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* Updates, 2005, John Rose <johnrose@austin.ibm.com>
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* Updates, 2005, Linas Vepstas <linas@austin.ibm.com>
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* Updates, 2013, Gavin Shan <shangw@linux.vnet.ibm.com>
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*/
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#include <linux/pci.h>
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#include <linux/export.h>
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#include <asm/pci-bridge.h>
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#include <asm/ppc-pci.h>
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#include <asm/firmware.h>
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#include <asm/eeh.h>
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static struct pci_bus *find_bus_among_children(struct pci_bus *bus,
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struct device_node *dn)
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{
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struct pci_bus *child = NULL;
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struct pci_bus *tmp;
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if (pci_bus_to_OF_node(bus) == dn)
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return bus;
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list_for_each_entry(tmp, &bus->children, node) {
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child = find_bus_among_children(tmp, dn);
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if (child)
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break;
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}
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return child;
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}
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struct pci_bus *pci_find_bus_by_node(struct device_node *dn)
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{
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struct pci_dn *pdn = PCI_DN(dn);
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if (!pdn || !pdn->phb || !pdn->phb->bus)
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return NULL;
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return find_bus_among_children(pdn->phb->bus, dn);
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}
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EXPORT_SYMBOL_GPL(pci_find_bus_by_node);
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/**
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* pcibios_release_device - release PCI device
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* @dev: PCI device
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*
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* The function is called before releasing the indicated PCI device.
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*/
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void pcibios_release_device(struct pci_dev *dev)
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{
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struct pci_controller *phb = pci_bus_to_host(dev->bus);
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struct pci_dn *pdn = pci_get_pdn(dev);
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eeh_remove_device(dev);
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if (phb->controller_ops.release_device)
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phb->controller_ops.release_device(dev);
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/* free()ing the pci_dn has been deferred to us, do it now */
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if (pdn && (pdn->flags & PCI_DN_FLAG_DEAD)) {
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pci_dbg(dev, "freeing dead pdn\n");
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kfree(pdn);
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}
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}
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/**
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* pci_hp_remove_devices - remove all devices under this bus
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* @bus: the indicated PCI bus
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*
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* Remove all of the PCI devices under this bus both from the
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* linux pci device tree, and from the powerpc EEH address cache.
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*/
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void pci_hp_remove_devices(struct pci_bus *bus)
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{
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struct pci_dev *dev, *tmp;
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struct pci_bus *child_bus;
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/* First go down child busses */
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list_for_each_entry(child_bus, &bus->children, node)
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pci_hp_remove_devices(child_bus);
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pr_debug("PCI: Removing devices on bus %04x:%02x\n",
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pci_domain_nr(bus), bus->number);
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list_for_each_entry_safe_reverse(dev, tmp, &bus->devices, bus_list) {
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pr_debug(" Removing %s...\n", pci_name(dev));
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pci_stop_and_remove_bus_device(dev);
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}
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}
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EXPORT_SYMBOL_GPL(pci_hp_remove_devices);
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/**
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* pci_hp_add_devices - adds new pci devices to bus
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* @bus: the indicated PCI bus
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*
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* This routine will find and fixup new pci devices under
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* the indicated bus. This routine presumes that there
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* might already be some devices under this bridge, so
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* it carefully tries to add only new devices. (And that
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* is how this routine differs from other, similar pcibios
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* routines.)
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*/
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void pci_hp_add_devices(struct pci_bus *bus)
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{
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int slotno, mode, max;
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struct pci_dev *dev;
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struct pci_controller *phb;
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struct device_node *dn = pci_bus_to_OF_node(bus);
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eeh_add_device_tree_early(PCI_DN(dn));
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phb = pci_bus_to_host(bus);
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mode = PCI_PROBE_NORMAL;
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if (phb->controller_ops.probe_mode)
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mode = phb->controller_ops.probe_mode(bus);
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if (mode == PCI_PROBE_DEVTREE) {
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/* use ofdt-based probe */
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of_rescan_bus(dn, bus);
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} else if (mode == PCI_PROBE_NORMAL &&
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dn->child && PCI_DN(dn->child)) {
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/*
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* Use legacy probe. In the partial hotplug case, we
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* probably have grandchildren devices unplugged. So
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* we don't check the return value from pci_scan_slot() in
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* order for fully rescan all the way down to pick them up.
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* They can have been removed during partial hotplug.
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*/
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slotno = PCI_SLOT(PCI_DN(dn->child)->devfn);
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pci_scan_slot(bus, PCI_DEVFN(slotno, 0));
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pcibios_setup_bus_devices(bus);
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max = bus->busn_res.start;
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/*
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* Scan bridges that are already configured. We don't touch
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* them unless they are misconfigured (which will be done in
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* the second scan below).
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*/
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for_each_pci_bridge(dev, bus)
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max = pci_scan_bridge(bus, dev, max, 0);
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/* Scan bridges that need to be reconfigured */
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for_each_pci_bridge(dev, bus)
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max = pci_scan_bridge(bus, dev, max, 1);
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}
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pcibios_finish_adding_to_bus(bus);
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}
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EXPORT_SYMBOL_GPL(pci_hp_add_devices);
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