[PATCH 2/2] PCI: add remove_id sysfs entry

Chris Wright
2009-02-24T02:18:29Z

This adds a remove_id sysfs entry to allow users of new_id to later
remove the added dynid. One use case is management tools that want to
dynamically bind/unbind devices to pci-stub driver while devices are
assigned to KVM guests. Rather than having to track which driver was
originally bound to the driver, a mangement tool can simply:

# echo "8086 10f5" > /sys/bus/pci/drivers/pci-stub/new_id
# echo -n 0000:00:19.0 > /sys/bus/pci/devices/0000:00:19.0/driver/unbind
# echo -n 0000:00:19.0 > /sys/bus/pci/drivers/pci-stub/bind

Guest uses device

# echo "8086 10f5" > /sys/bus/pci/drivers/pci-stub/remove_id
# echo 0000:00:19.0 > /sys/bus/pci/drivers_probe

Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---
Documentation/ABI/testing/sysfs-bus-pci | 16 ++++++
drivers/pci/pci-driver.c | 80 +++++++++++++++++++++++++++++++-
2 files changed, 94 insertions(+), 2 deletions(-)

--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -99,6 +99,52 @@ store_new_id(struct device_driver *drive
}
static DRIVER_ATTR(new_id, S_IWUSR, NULL, store_new_id);

+/**
+ * store_remove_id - remove a PCI device ID from this driver
+ * @driver: target device driver
+ * @buf: buffer for scanning device ID data
+ * @count: input size
+ *
+ * Removes a dynamic pci device ID to this driver.
+ */
+static ssize_t
+store_remove_id(struct device_driver *driver, const char *buf, size_t count)
+{
+ struct pci_dynid *dynid, *n;
+ struct pci_driver *pdrv = to_pci_driver(driver);
+ __u32 vendor, device, subvendor = PCI_ANY_ID,
+ subdevice = PCI_ANY_ID, class = 0, class_mask = 0;
+ int fields = 0;
+ int retval = -ENODEV;
+
+ fields = sscanf(buf, "%x %x %x %x %x %x",
+ &vendor, &device, &subvendor, &subdevice,
+ &class, &class_mask);
+ if (fields < 2)
+ return -EINVAL;
+
+ spin_lock(&pdrv->dynids.lock);
+ list_for_each_entry_safe(dynid, n, &pdrv->dynids.list, node) {
+ struct pci_device_id *id = &dynid->id;
+ if ((id->vendor == vendor) &&
+ (id->device == device) &&
+ (subvendor == PCI_ANY_ID || id->subvendor == subvendor) &&
+ (subdevice == PCI_ANY_ID || id->subdevice == subdevice) &&
+ !((id->class ^ class) & class_mask)) {
+ list_del(&dynid->node);
+ kfree(dynid);
+ retval = 0;
+ break;
+ }
+ }
+ spin_unlock(&pdrv->dynids.lock);
+
+ if (retval)
+ return retval;
+ return count;
+}
+static DRIVER_ATTR(remove_id, S_IWUSR, NULL, store_remove_id);
+
static void
pci_free_dynids(struct pci_driver *drv)
{
@@ -125,6 +171,20 @@ static void pci_remove_newid_file(struct
{
driver_remove_file(&drv->driver, &driver_attr_new_id);
}
+
+static int
+pci_create_removeid_file(struct pci_driver *drv)
+{
+ int error = 0;
+ if (drv->probe != NULL)
+ error = driver_create_file(&drv->driver,&driver_attr_remove_id);
+ return error;
+}
+
+static void pci_remove_removeid_file(struct pci_driver *drv)
+{
+ driver_remove_file(&drv->driver, &driver_attr_remove_id);
+}
#else /* !CONFIG_HOTPLUG */
static inline void pci_free_dynids(struct pci_driver *drv) {}
static inline int pci_create_newid_file(struct pci_driver *drv)
@@ -132,6 +192,11 @@ static inline int pci_create_newid_file(
return 0;
}
static inline void pci_remove_newid_file(struct pci_driver *drv) {}
+static inline int pci_create_removeid_file(struct pci_driver *drv)
+{
+ return 0;
+}
+static inline void pci_remove_removeid_file(struct pci_driver *drv) {}
#endif

/**
@@ -852,13 +917,23 @@ int __pci_register_driver(struct pci_dri
/* register with core */
error = driver_register(&drv->driver);
if (error)
- return error;
+ goto out;

error = pci_create_newid_file(drv);
if (error)
- driver_unregister(&drv->driver);
+ goto out_newid;

+ error = pci_create_removeid_file(drv);
+ if (error)
+ goto out_removeid;
+out:
return error;
+
+out_removeid:
+ pci_remove_newid_file(drv);
+out_newid:
+ driver_unregister(&drv->driver);
+ goto out;
}

/**
@@ -874,6 +949,7 @@ int __pci_register_driver(struct pci_dri
void
pci_unregister_driver(struct pci_driver *drv)
{
+ pci_remove_removeid_file(drv);
pci_remove_newid_file(drv);
driver_unregister(&drv->driver);
pci_free_dynids(drv);
--- a/Documentation/ABI/testing/sysfs-bus-pci
+++ b/Documentation/ABI/testing/sysfs-bus-pci
@@ -39,6 +39,22 @@ Description:
for the device and attempt to bind to it. For example:
# echo 8086 10f5 > /sys/bus/pci/drivers/foo/new_id

+What: /sys/bus/pci/drivers/.../remove_id
+Date: February 2009
+Contact: Chris Wright <chrisw@sous-sol.org>
+Description:
+ Writing a device ID to this file will remove an ID
+ that was dynamically added via the new_id sysfs entry.
+ The format for the device ID is:
+ VVVV DDDD SVVV SDDD CCCC MMMM. That is Vendor ID, Device
+ ID, Subsystem Vendor ID, Subsystem Device ID, Class,
+ and Class Mask. The Vendor ID and Device ID fields are
+ required, the rest are optional. After successfully
+ removing an ID, the driver will no longer support the
+ device. This is useful to ensure auto probing won't
+ match the driver to the device. For example:
+ # echo 8086 10f5 > /sys/bus/pci/drivers/foo/remove_id
+
What: /sys/bus/pci/devices/.../vpd
Date: February 2008
Contact: Ben Hutchings <bhutchings@solarflare.com>