linux-stable/drivers/pci/search.c
Matthew Wilcox c4ed02fae7 PCI: Fix reference counting bug
pci_get_subsys() will decrement the reference count of the device that
it starts searching from.  Unfortunately, the pci_find_device() interface
will already have decremented the reference count of the device earlier,
so the device will end up losing all reference counts and be freed.

We can fix this by incrementing the reference count of the device to
start searching from before calling pci_get_subsys().

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
2008-10-22 16:42:35 -07:00

419 lines
13 KiB
C

/*
* PCI searching functions.
*
* Copyright (C) 1993 -- 1997 Drew Eckhardt, Frederic Potter,
* David Mosberger-Tang
* Copyright (C) 1997 -- 2000 Martin Mares <mj@ucw.cz>
* Copyright (C) 2003 -- 2004 Greg Kroah-Hartman <greg@kroah.com>
*/
#include <linux/init.h>
#include <linux/pci.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include "pci.h"
DECLARE_RWSEM(pci_bus_sem);
/*
* find the upstream PCIE-to-PCI bridge of a PCI device
* if the device is PCIE, return NULL
* if the device isn't connected to a PCIE bridge (that is its parent is a
* legacy PCI bridge and the bridge is directly connected to bus 0), return its
* parent
*/
struct pci_dev *
pci_find_upstream_pcie_bridge(struct pci_dev *pdev)
{
struct pci_dev *tmp = NULL;
if (pdev->is_pcie)
return NULL;
while (1) {
if (!pdev->bus->self)
break;
pdev = pdev->bus->self;
/* a p2p bridge */
if (!pdev->is_pcie) {
tmp = pdev;
continue;
}
/* PCI device should connect to a PCIE bridge */
if (pdev->pcie_type != PCI_EXP_TYPE_PCI_BRIDGE) {
/* Busted hardware? */
WARN_ON_ONCE(1);
return NULL;
}
return pdev;
}
return tmp;
}
static struct pci_bus *pci_do_find_bus(struct pci_bus *bus, unsigned char busnr)
{
struct pci_bus* child;
struct list_head *tmp;
if(bus->number == busnr)
return bus;
list_for_each(tmp, &bus->children) {
child = pci_do_find_bus(pci_bus_b(tmp), busnr);
if(child)
return child;
}
return NULL;
}
/**
* pci_find_bus - locate PCI bus from a given domain and bus number
* @domain: number of PCI domain to search
* @busnr: number of desired PCI bus
*
* Given a PCI bus number and domain number, the desired PCI bus is located
* in the global list of PCI buses. If the bus is found, a pointer to its
* data structure is returned. If no bus is found, %NULL is returned.
*/
struct pci_bus * pci_find_bus(int domain, int busnr)
{
struct pci_bus *bus = NULL;
struct pci_bus *tmp_bus;
while ((bus = pci_find_next_bus(bus)) != NULL) {
if (pci_domain_nr(bus) != domain)
continue;
tmp_bus = pci_do_find_bus(bus, busnr);
if (tmp_bus)
return tmp_bus;
}
return NULL;
}
/**
* pci_find_next_bus - begin or continue searching for a PCI bus
* @from: Previous PCI bus found, or %NULL for new search.
*
* Iterates through the list of known PCI busses. A new search is
* initiated by passing %NULL as the @from argument. Otherwise if
* @from is not %NULL, searches continue from next device on the
* global list.
*/
struct pci_bus *
pci_find_next_bus(const struct pci_bus *from)
{
struct list_head *n;
struct pci_bus *b = NULL;
WARN_ON(in_interrupt());
down_read(&pci_bus_sem);
n = from ? from->node.next : pci_root_buses.next;
if (n != &pci_root_buses)
b = pci_bus_b(n);
up_read(&pci_bus_sem);
return b;
}
#ifdef CONFIG_PCI_LEGACY
/**
* pci_find_slot - locate PCI device from a given PCI slot
* @bus: number of PCI bus on which desired PCI device resides
* @devfn: encodes number of PCI slot in which the desired PCI
* device resides and the logical device number within that slot
* in case of multi-function devices.
*
* Given a PCI bus and slot/function number, the desired PCI device
* is located in system global list of PCI devices. If the device
* is found, a pointer to its data structure is returned. If no
* device is found, %NULL is returned.
*
* NOTE: Do not use this function any more; use pci_get_slot() instead, as
* the PCI device returned by this function can disappear at any moment in
* time.
*/
struct pci_dev *pci_find_slot(unsigned int bus, unsigned int devfn)
{
struct pci_dev *dev = NULL;
while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL) {
if (dev->bus->number == bus && dev->devfn == devfn) {
pci_dev_put(dev);
return dev;
}
}
return NULL;
}
EXPORT_SYMBOL(pci_find_slot);
/**
* pci_find_device - begin or continue searching for a PCI device by vendor/device id
* @vendor: PCI vendor id to match, or %PCI_ANY_ID to match all vendor ids
* @device: PCI device id to match, or %PCI_ANY_ID to match all device ids
* @from: Previous PCI device found in search, or %NULL for new search.
*
* Iterates through the list of known PCI devices. If a PCI device is found
* with a matching @vendor and @device, a pointer to its device structure is
* returned. Otherwise, %NULL is returned.
* A new search is initiated by passing %NULL as the @from argument.
* Otherwise if @from is not %NULL, searches continue from next device
* on the global list.
*
* NOTE: Do not use this function any more; use pci_get_device() instead, as
* the PCI device returned by this function can disappear at any moment in
* time.
*/
struct pci_dev *pci_find_device(unsigned int vendor, unsigned int device,
struct pci_dev *from)
{
struct pci_dev *pdev;
pci_dev_get(from);
pdev = pci_get_subsys(vendor, device, PCI_ANY_ID, PCI_ANY_ID, from);
pci_dev_put(pdev);
return pdev;
}
EXPORT_SYMBOL(pci_find_device);
#endif /* CONFIG_PCI_LEGACY */
/**
* pci_get_slot - locate PCI device for a given PCI slot
* @bus: PCI bus on which desired PCI device resides
* @devfn: encodes number of PCI slot in which the desired PCI
* device resides and the logical device number within that slot
* in case of multi-function devices.
*
* Given a PCI bus and slot/function number, the desired PCI device
* is located in the list of PCI devices.
* If the device is found, its reference count is increased and this
* function returns a pointer to its data structure. The caller must
* decrement the reference count by calling pci_dev_put().
* If no device is found, %NULL is returned.
*/
struct pci_dev * pci_get_slot(struct pci_bus *bus, unsigned int devfn)
{
struct list_head *tmp;
struct pci_dev *dev;
WARN_ON(in_interrupt());
down_read(&pci_bus_sem);
list_for_each(tmp, &bus->devices) {
dev = pci_dev_b(tmp);
if (dev->devfn == devfn)
goto out;
}
dev = NULL;
out:
pci_dev_get(dev);
up_read(&pci_bus_sem);
return dev;
}
/**
* pci_get_bus_and_slot - locate PCI device from a given PCI bus & slot
* @bus: number of PCI bus on which desired PCI device resides
* @devfn: encodes number of PCI slot in which the desired PCI
* device resides and the logical device number within that slot
* in case of multi-function devices.
*
* Note: the bus/slot search is limited to PCI domain (segment) 0.
*
* Given a PCI bus and slot/function number, the desired PCI device
* is located in system global list of PCI devices. If the device
* is found, a pointer to its data structure is returned. If no
* device is found, %NULL is returned. The returned device has its
* reference count bumped by one.
*/
struct pci_dev * pci_get_bus_and_slot(unsigned int bus, unsigned int devfn)
{
struct pci_dev *dev = NULL;
while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL) {
if (pci_domain_nr(dev->bus) == 0 &&
(dev->bus->number == bus && dev->devfn == devfn))
return dev;
}
return NULL;
}
static int match_pci_dev_by_id(struct device *dev, void *data)
{
struct pci_dev *pdev = to_pci_dev(dev);
struct pci_device_id *id = data;
if (pci_match_one_device(id, pdev))
return 1;
return 0;
}
/*
* pci_get_dev_by_id - begin or continue searching for a PCI device by id
* @id: pointer to struct pci_device_id to match for the device
* @from: Previous PCI device found in search, or %NULL for new search.
*
* Iterates through the list of known PCI devices. If a PCI device is found
* with a matching id a pointer to its device structure is returned, and the
* reference count to the device is incremented. Otherwise, %NULL is returned.
* A new search is initiated by passing %NULL as the @from argument. Otherwise
* if @from is not %NULL, searches continue from next device on the global
* list. The reference count for @from is always decremented if it is not
* %NULL.
*
* This is an internal function for use by the other search functions in
* this file.
*/
static struct pci_dev *pci_get_dev_by_id(const struct pci_device_id *id,
struct pci_dev *from)
{
struct device *dev;
struct device *dev_start = NULL;
struct pci_dev *pdev = NULL;
WARN_ON(in_interrupt());
if (from)
dev_start = &from->dev;
dev = bus_find_device(&pci_bus_type, dev_start, (void *)id,
match_pci_dev_by_id);
if (dev)
pdev = to_pci_dev(dev);
if (from)
pci_dev_put(from);
return pdev;
}
/**
* pci_get_subsys - begin or continue searching for a PCI device by vendor/subvendor/device/subdevice id
* @vendor: PCI vendor id to match, or %PCI_ANY_ID to match all vendor ids
* @device: PCI device id to match, or %PCI_ANY_ID to match all device ids
* @ss_vendor: PCI subsystem vendor id to match, or %PCI_ANY_ID to match all vendor ids
* @ss_device: PCI subsystem device id to match, or %PCI_ANY_ID to match all device ids
* @from: Previous PCI device found in search, or %NULL for new search.
*
* Iterates through the list of known PCI devices. If a PCI device is found
* with a matching @vendor, @device, @ss_vendor and @ss_device, a pointer to its
* device structure is returned, and the reference count to the device is
* incremented. Otherwise, %NULL is returned. A new search is initiated by
* passing %NULL as the @from argument. Otherwise if @from is not %NULL,
* searches continue from next device on the global list.
* The reference count for @from is always decremented if it is not %NULL.
*/
struct pci_dev *pci_get_subsys(unsigned int vendor, unsigned int device,
unsigned int ss_vendor, unsigned int ss_device,
struct pci_dev *from)
{
struct pci_dev *pdev;
struct pci_device_id *id;
/*
* pci_find_subsys() can be called on the ide_setup() path,
* super-early in boot. But the down_read() will enable local
* interrupts, which can cause some machines to crash. So here we
* detect and flag that situation and bail out early.
*/
if (unlikely(no_pci_devices()))
return NULL;
id = kzalloc(sizeof(*id), GFP_KERNEL);
if (!id)
return NULL;
id->vendor = vendor;
id->device = device;
id->subvendor = ss_vendor;
id->subdevice = ss_device;
pdev = pci_get_dev_by_id(id, from);
kfree(id);
return pdev;
}
/**
* pci_get_device - begin or continue searching for a PCI device by vendor/device id
* @vendor: PCI vendor id to match, or %PCI_ANY_ID to match all vendor ids
* @device: PCI device id to match, or %PCI_ANY_ID to match all device ids
* @from: Previous PCI device found in search, or %NULL for new search.
*
* Iterates through the list of known PCI devices. If a PCI device is
* found with a matching @vendor and @device, the reference count to the
* device is incremented and a pointer to its device structure is returned.
* Otherwise, %NULL is returned. A new search is initiated by passing %NULL
* as the @from argument. Otherwise if @from is not %NULL, searches continue
* from next device on the global list. The reference count for @from is
* always decremented if it is not %NULL.
*/
struct pci_dev *
pci_get_device(unsigned int vendor, unsigned int device, struct pci_dev *from)
{
return pci_get_subsys(vendor, device, PCI_ANY_ID, PCI_ANY_ID, from);
}
/**
* pci_get_class - begin or continue searching for a PCI device by class
* @class: search for a PCI device with this class designation
* @from: Previous PCI device found in search, or %NULL for new search.
*
* Iterates through the list of known PCI devices. If a PCI device is
* found with a matching @class, the reference count to the device is
* incremented and a pointer to its device structure is returned.
* Otherwise, %NULL is returned.
* A new search is initiated by passing %NULL as the @from argument.
* Otherwise if @from is not %NULL, searches continue from next device
* on the global list. The reference count for @from is always decremented
* if it is not %NULL.
*/
struct pci_dev *pci_get_class(unsigned int class, struct pci_dev *from)
{
struct pci_dev *dev;
struct pci_device_id *id;
id = kzalloc(sizeof(*id), GFP_KERNEL);
if (!id)
return NULL;
id->vendor = id->device = id->subvendor = id->subdevice = PCI_ANY_ID;
id->class_mask = PCI_ANY_ID;
id->class = class;
dev = pci_get_dev_by_id(id, from);
kfree(id);
return dev;
}
/**
* pci_dev_present - Returns 1 if device matching the device list is present, 0 if not.
* @ids: A pointer to a null terminated list of struct pci_device_id structures
* that describe the type of PCI device the caller is trying to find.
*
* Obvious fact: You do not have a reference to any device that might be found
* by this function, so if that device is removed from the system right after
* this function is finished, the value will be stale. Use this function to
* find devices that are usually built into a system, or for a general hint as
* to if another device happens to be present at this specific moment in time.
*/
int pci_dev_present(const struct pci_device_id *ids)
{
struct pci_dev *found = NULL;
WARN_ON(in_interrupt());
while (ids->vendor || ids->subvendor || ids->class_mask) {
found = pci_get_dev_by_id(ids, NULL);
if (found)
goto exit;
ids++;
}
exit:
if (found)
return 1;
return 0;
}
EXPORT_SYMBOL(pci_dev_present);
/* For boot time work */
EXPORT_SYMBOL(pci_find_bus);
EXPORT_SYMBOL(pci_find_next_bus);
/* For everyone */
EXPORT_SYMBOL(pci_get_device);
EXPORT_SYMBOL(pci_get_subsys);
EXPORT_SYMBOL(pci_get_slot);
EXPORT_SYMBOL(pci_get_bus_and_slot);
EXPORT_SYMBOL(pci_get_class);