Here's the latest version of the pci list locking patch. I've taken
Chris's comments and addressed them by making sure we don't walk off the
end of a deleted device in the pci_find_* and pci_get_* functions.
This version has survived a pretty hard beating on a pci hotplug system,
as proof of concept...
Comments?
thanks,
greg k-h
--- a/drivers/pci/bus.c Thu Jun 19 11:08:53 2003
+++ b/drivers/pci/bus.c Thu Jun 19 11:08:53 2003
@@ -93,7 +93,11 @@
continue;
device_add(&dev->dev);
+
+ spin_lock(&pci_bus_lock);
list_add_tail(&dev->global_list, &pci_devices);
+ spin_unlock(&pci_bus_lock);
+
pci_proc_attach_device(dev);
pci_create_sysfs_dev_files(dev);
@@ -108,7 +112,9 @@
* it and then scan for unattached PCI devices.
*/
if (dev->subordinate && list_empty(&dev->subordinate->node)) {
+ spin_lock(&pci_bus_lock);
list_add_tail(&dev->subordinate->node, &dev->bus->children);
+ spin_unlock(&pci_bus_lock);
pci_bus_add_devices(dev->subordinate);
}
}
--- a/drivers/pci/hotplug.c Thu Jun 19 11:08:53 2003
+++ b/drivers/pci/hotplug.c Thu Jun 19 11:08:53 2003
@@ -173,6 +173,24 @@
}
EXPORT_SYMBOL(pci_visit_dev);
+static void pci_destroy_dev(struct pci_dev *dev)
+{
+ device_unregister(&dev->dev);
+
+ /* Remove the device from the device lists, and prevent any further
+ * list accesses from this device */
+ spin_lock(&pci_bus_lock);
+ list_del(&dev->bus_list);
+ list_del(&dev->global_list);
+ dev->bus_list.next = dev->bus_list.prev = NULL;
+ dev->global_list.next = dev->global_list.prev = NULL;
+ spin_unlock(&pci_bus_lock);
+
+ pci_free_resources(dev);
+ pci_proc_detach_device(dev);
+ pci_put_dev(dev);
+}
+
/**
* pci_remove_device_safe - remove an unused hotplug device
* @dev: the device to remove
@@ -186,11 +204,7 @@
{
if (pci_dev_driver(dev))
return -EBUSY;
- device_unregister(&dev->dev);
- list_del(&dev->bus_list);
- list_del(&dev->global_list);
- pci_free_resources(dev);
- pci_proc_detach_device(dev);
+ pci_destroy_dev(dev);
return 0;
}
EXPORT_SYMBOL(pci_remove_device_safe);
@@ -237,17 +251,15 @@
pci_remove_behind_bridge(dev);
pci_proc_detach_bus(b);
+ spin_lock(&pci_bus_lock);
list_del(&b->node);
+ spin_unlock(&pci_bus_lock);
+
kfree(b);
dev->subordinate = NULL;
}
- device_unregister(&dev->dev);
- list_del(&dev->bus_list);
- list_del(&dev->global_list);
- pci_free_resources(dev);
- pci_proc_detach_device(dev);
- pci_put_dev(dev);
+ pci_destroy_dev(dev);
}
/**
--- a/drivers/pci/pci.h Thu Jun 19 11:08:53 2003
+++ b/drivers/pci/pci.h Thu Jun 19 11:08:53 2003
@@ -59,3 +59,6 @@
extern int pci_visit_dev(struct pci_visit *fn,
struct pci_dev_wrapped *wrapped_dev,
struct pci_bus_wrapped *wrapped_parent);
+
+/* Lock for read/write access to pci device and bus lists */
+extern spinlock_t pci_bus_lock;
--- a/drivers/pci/proc.c Thu Jun 19 11:08:53 2003
+++ b/drivers/pci/proc.c Thu Jun 19 11:08:53 2003
@@ -12,6 +12,7 @@
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/smp_lock.h>
+#include "pci.h"
#include <asm/uaccess.h>
#include <asm/byteorder.h>
@@ -308,39 +309,45 @@
/* iterator */
static void *pci_seq_start(struct seq_file *m, loff_t *pos)
{
- struct list_head *p = &pci_devices;
+ struct pci_dev *dev = NULL;
loff_t n = *pos;
- /* XXX: surely we need some locking for traversing the list? */
+ dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev);
while (n--) {
- p = p->next;
- if (p == &pci_devices)
- return NULL;
+ dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev);
+ if (dev == NULL)
+ goto exit;
}
- return p;
+exit:
+ return dev;
}
+
static void *pci_seq_next(struct seq_file *m, void *v, loff_t *pos)
{
- struct list_head *p = v;
+ struct pci_dev *dev = v;
+
(*pos)++;
- return p->next != &pci_devices ? (void *)p->next : NULL;
+ dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev);
+ return dev;
}
+
static void pci_seq_stop(struct seq_file *m, void *v)
{
- /* release whatever locks we need */
+ if (v) {
+ struct pci_dev *dev = v;
+ pci_put_dev(dev);
+ }
}
static int show_device(struct seq_file *m, void *v)
{
- struct list_head *p = v;
- const struct pci_dev *dev;
+ const struct pci_dev *dev = v;
const struct pci_driver *drv;
int i;
- if (p == &pci_devices)
+ if (dev == NULL)
return 0;
- dev = pci_dev_g(p);
drv = pci_dev_driver(dev);
seq_printf(m, "%02x%02x\t%04x%04x\t%x",
dev->bus->number,
@@ -455,19 +462,18 @@
*/
static int show_dev_config(struct seq_file *m, void *v)
{
- struct list_head *p = v;
- struct pci_dev *dev;
+ struct pci_dev *dev = v;
+ struct pci_dev *first_dev;
struct pci_driver *drv;
u32 class_rev;
unsigned char latency, min_gnt, max_lat, *class;
int reg;
- if (p == &pci_devices) {
+ first_dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, NULL);
+ if (dev == first_dev)
seq_puts(m, "PCI devices found:\n");
- return 0;
- }
+ pci_put_dev(first_dev);
- dev = pci_dev_g(p);
drv = pci_dev_driver(dev);
pci_read_config_dword(dev, PCI_CLASS_REVISION, &class_rev);
--- a/drivers/pci/search.c Thu Jun 19 11:08:53 2003
+++ b/drivers/pci/search.c Thu Jun 19 11:08:53 2003
@@ -1,6 +1,17 @@
+/*
+ * PCI searching functions.
+ *
+ * Copyright 1993 -- 1997 Drew Eckhardt, Frederic Potter,
+ * David Mosberger-Tang
+ * Copyright 1997 -- 2000 Martin Mares <mj@ucw.cz>
+ * Copyright 2003 -- Greg Kroah-Hartman <greg@kroah.com>
+ */
+
#include <linux/pci.h>
#include <linux/module.h>
+spinlock_t pci_bus_lock = SPIN_LOCK_UNLOCKED;
+
static struct pci_bus *
pci_do_find_bus(struct pci_bus* bus, unsigned char busnr)
{
@@ -52,11 +63,15 @@
struct pci_bus *
pci_find_next_bus(const struct pci_bus *from)
{
- struct list_head *n = from ? from->node.next : pci_root_buses.next;
+ struct list_head *n;
struct pci_bus *b = NULL;
+ WARN_ON(irqs_disabled());
+ spin_lock(&pci_bus_lock);
+ n = from ? from->node.next : pci_root_buses.next;
if (n != &pci_root_buses)
b = pci_bus_b(n);
+ spin_unlock(&pci_bus_lock);
return b;
}
@@ -97,24 +112,36 @@
* device structure is returned. Otherwise, %NULL is returned.
* A new search is initiated by passing %NULL to the @from argument.
* Otherwise if @from is not %NULL, searches continue from next device on the global list.
+ *
+ * NOTE: Do not use this function anymore, use pci_get_subsys() instead, as
+ * the pci device returned by this function can disappear at any moment in
+ * time.
*/
struct pci_dev *
pci_find_subsys(unsigned int vendor, unsigned int device,
unsigned int ss_vendor, unsigned int ss_device,
const struct pci_dev *from)
{
- struct list_head *n = from ? from->global_list.next : pci_devices.next;
+ struct list_head *n;
+ struct pci_dev *dev;
+
+ WARN_ON(irqs_disabled());
+ spin_lock(&pci_bus_lock);
+ n = from ? from->global_list.next : pci_devices.next;
- while (n != &pci_devices) {
- struct pci_dev *dev = pci_dev_g(n);
+ while (n && (n != &pci_devices)) {
+ dev = pci_dev_g(n);
if ((vendor == PCI_ANY_ID || dev->vendor == vendor) &&
(device == PCI_ANY_ID || dev->device == device) &&
(ss_vendor == PCI_ANY_ID || dev->subsystem_vendor == ss_vendor) &&
(ss_device == PCI_ANY_ID || dev->subsystem_device == ss_device))
- return dev;
+ goto exit;
n = n->next;
}
- return NULL;
+ dev = NULL;
+exit:
+ spin_unlock(&pci_bus_lock);
+ return dev;
}
/**
@@ -128,6 +155,10 @@
* returned. Otherwise, %NULL is returned.
* A new search is initiated by passing %NULL to the @from argument.
* Otherwise if @from is not %NULL, searches continue from next device on the global list.
+ *
+ * NOTE: Do not use this function anymore, 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, const struct pci_dev *from)
@@ -135,6 +166,77 @@
return pci_find_subsys(vendor, device, PCI_ANY_ID, PCI_ANY_ID, from);
}
+/**
+ * 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 to 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 list_head *n;
+ struct pci_dev *dev;
+
+ WARN_ON(irqs_disabled());
+ spin_lock(&pci_bus_lock);
+ n = from ? from->global_list.next : pci_devices.next;
+
+ while (n && (n != &pci_devices)) {
+ dev = pci_dev_g(n);
+ if ((vendor == PCI_ANY_ID || dev->vendor == vendor) &&
+ (device == PCI_ANY_ID || dev->device == device) &&
+ (ss_vendor == PCI_ANY_ID || dev->subsystem_vendor == ss_vendor) &&
+ (ss_device == PCI_ANY_ID || dev->subsystem_device == ss_device))
+ goto exit;
+ n = n->next;
+ }
+ dev = NULL;
+exit:
+ pci_put_dev(from);
+ dev = pci_get_dev(dev);
+ spin_unlock(&pci_bus_lock);
+ return dev;
+}
+
+/**
+ * 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, a pointer to its device structure is
+ * returned. Otherwise, %NULL is returned.
+ * A new search is initiated by passing %NULL to the @from argument.
+ * Otherwise if @from is not %NULL, searches continue from next device on the global list.
+ *
+ * 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
+ * to 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_find_device_reverse - begin or continue searching for a PCI device by vendor/device id
@@ -151,16 +253,24 @@
struct pci_dev *
pci_find_device_reverse(unsigned int vendor, unsigned int device, const struct pci_dev *from)
{
- struct list_head *n = from ? from->global_list.prev : pci_devices.prev;
+ struct list_head *n;
+ struct pci_dev *dev;
- while (n != &pci_devices) {
- struct pci_dev *dev = pci_dev_g(n);
+ WARN_ON(irqs_disabled());
+ spin_lock(&pci_bus_lock);
+ n = from ? from->global_list.prev : pci_devices.prev;
+
+ while (n && (n != &pci_devices)) {
+ dev = pci_dev_g(n);
if ((vendor == PCI_ANY_ID || dev->vendor == vendor) &&
(device == PCI_ANY_ID || dev->device == device))
- return dev;
+ goto exit;
n = n->prev;
}
- return NULL;
+ dev = NULL;
+exit:
+ spin_unlock(&pci_bus_lock);
+ return dev;
}
@@ -179,15 +289,22 @@
struct pci_dev *
pci_find_class(unsigned int class, const struct pci_dev *from)
{
- struct list_head *n = from ? from->global_list.next : pci_devices.next;
+ struct list_head *n;
+ struct pci_dev *dev;
- while (n != &pci_devices) {
- struct pci_dev *dev = pci_dev_g(n);
+ spin_lock(&pci_bus_lock);
+ n = from ? from->global_list.next : pci_devices.next;
+
+ while (n && (n != &pci_devices)) {
+ dev = pci_dev_g(n);
if (dev->class == class)
- return dev;
+ goto exit;
n = n->next;
}
- return NULL;
+ dev = NULL;
+exit:
+ spin_unlock(&pci_bus_lock);
+ return dev;
}
EXPORT_SYMBOL(pci_find_bus);
@@ -196,3 +313,5 @@
EXPORT_SYMBOL(pci_find_device_reverse);
EXPORT_SYMBOL(pci_find_slot);
EXPORT_SYMBOL(pci_find_subsys);
+EXPORT_SYMBOL(pci_get_device);
+EXPORT_SYMBOL(pci_get_subsys);
--- a/include/linux/pci.h Thu Jun 19 11:08:53 2003
+++ b/include/linux/pci.h Thu Jun 19 11:08:53 2003
@@ -566,6 +566,10 @@
int pci_find_capability (struct pci_dev *dev, int cap);
struct pci_bus * pci_find_next_bus(const struct pci_bus *from);
+struct pci_dev *pci_get_device (unsigned int vendor, unsigned int device, struct pci_dev *from);
+struct pci_dev *pci_get_subsys (unsigned int vendor, unsigned int device,
+ unsigned int ss_vendor, unsigned int ss_device,
+ struct pci_dev *from);
int pci_bus_read_config_byte (struct pci_bus *bus, unsigned int devfn, int where, u8 *val);
int pci_bus_read_config_word (struct pci_bus *bus, unsigned int devfn, int where, u16 *val);
int pci_bus_read_config_dword (struct pci_bus *bus, unsigned int devfn, int where, u32 *val);
@@ -686,6 +690,13 @@
static inline struct pci_dev *pci_find_subsys(unsigned int vendor, unsigned int device,
unsigned int ss_vendor, unsigned int ss_device, const struct pci_dev *from)
+{ return NULL; }
+
+static inline struct pci_dev *pci_get_device (unsigned int vendor, unsigned int device, struct pci_dev *from)
+{ return NULL; }
+
+static inline struct pci_dev *pci_get_subsys (unsigned int vendor, unsigned int device,
+unsigned int ss_vendor, unsigned int ss_device, struct pci_dev *from)
{ return NULL; }
static inline void pci_set_master(struct pci_dev *dev) { }
-
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