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Merge branch 'pci/reset' into next
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* pci/reset:
  vfio-pci: Use pci "try" reset interface
  PCI: Add pci_try_reset_function(), pci_try_reset_slot(), pci_try_reset_bus()
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Bjorn Helgaas committed Jan 15, 2014
2 parents 4030461 + 890ed57 commit 6e2d98d
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Showing 3 changed files with 167 additions and 20 deletions.
155 changes: 155 additions & 0 deletions drivers/pci/pci.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3250,6 +3250,18 @@ static void pci_dev_lock(struct pci_dev *dev)
device_lock(&dev->dev);
}

/* Return 1 on successful lock, 0 on contention */
static int pci_dev_trylock(struct pci_dev *dev)
{
if (pci_cfg_access_trylock(dev)) {
if (device_trylock(&dev->dev))
return 1;
pci_cfg_access_unlock(dev);
}

return 0;
}

static void pci_dev_unlock(struct pci_dev *dev)
{
device_unlock(&dev->dev);
Expand Down Expand Up @@ -3393,6 +3405,34 @@ int pci_reset_function(struct pci_dev *dev)
}
EXPORT_SYMBOL_GPL(pci_reset_function);

/**
* pci_try_reset_function - quiesce and reset a PCI device function
* @dev: PCI device to reset
*
* Same as above, except return -EAGAIN if unable to lock device.
*/
int pci_try_reset_function(struct pci_dev *dev)
{
int rc;

rc = pci_dev_reset(dev, 1);
if (rc)
return rc;

pci_dev_save_and_disable(dev);

if (pci_dev_trylock(dev)) {
rc = __pci_dev_reset(dev, 0);
pci_dev_unlock(dev);
} else
rc = -EAGAIN;

pci_dev_restore(dev);

return rc;
}
EXPORT_SYMBOL_GPL(pci_try_reset_function);

/* Lock devices from the top of the tree down */
static void pci_bus_lock(struct pci_bus *bus)
{
Expand All @@ -3417,6 +3457,32 @@ static void pci_bus_unlock(struct pci_bus *bus)
}
}

/* Return 1 on successful lock, 0 on contention */
static int pci_bus_trylock(struct pci_bus *bus)
{
struct pci_dev *dev;

list_for_each_entry(dev, &bus->devices, bus_list) {
if (!pci_dev_trylock(dev))
goto unlock;
if (dev->subordinate) {
if (!pci_bus_trylock(dev->subordinate)) {
pci_dev_unlock(dev);
goto unlock;
}
}
}
return 1;

unlock:
list_for_each_entry_continue_reverse(dev, &bus->devices, bus_list) {
if (dev->subordinate)
pci_bus_unlock(dev->subordinate);
pci_dev_unlock(dev);
}
return 0;
}

/* Lock devices from the top of the tree down */
static void pci_slot_lock(struct pci_slot *slot)
{
Expand Down Expand Up @@ -3445,6 +3511,37 @@ static void pci_slot_unlock(struct pci_slot *slot)
}
}

/* Return 1 on successful lock, 0 on contention */
static int pci_slot_trylock(struct pci_slot *slot)
{
struct pci_dev *dev;

list_for_each_entry(dev, &slot->bus->devices, bus_list) {
if (!dev->slot || dev->slot != slot)
continue;
if (!pci_dev_trylock(dev))
goto unlock;
if (dev->subordinate) {
if (!pci_bus_trylock(dev->subordinate)) {
pci_dev_unlock(dev);
goto unlock;
}
}
}
return 1;

unlock:
list_for_each_entry_continue_reverse(dev,
&slot->bus->devices, bus_list) {
if (!dev->slot || dev->slot != slot)
continue;
if (dev->subordinate)
pci_bus_unlock(dev->subordinate);
pci_dev_unlock(dev);
}
return 0;
}

/* Save and disable devices from the top of the tree down */
static void pci_bus_save_and_disable(struct pci_bus *bus)
{
Expand Down Expand Up @@ -3568,6 +3665,35 @@ int pci_reset_slot(struct pci_slot *slot)
}
EXPORT_SYMBOL_GPL(pci_reset_slot);

/**
* pci_try_reset_slot - Try to reset a PCI slot
* @slot: PCI slot to reset
*
* Same as above except return -EAGAIN if the slot cannot be locked
*/
int pci_try_reset_slot(struct pci_slot *slot)
{
int rc;

rc = pci_slot_reset(slot, 1);
if (rc)
return rc;

pci_slot_save_and_disable(slot);

if (pci_slot_trylock(slot)) {
might_sleep();
rc = pci_reset_hotplug_slot(slot->hotplug, 0);
pci_slot_unlock(slot);
} else
rc = -EAGAIN;

pci_slot_restore(slot);

return rc;
}
EXPORT_SYMBOL_GPL(pci_try_reset_slot);

static int pci_bus_reset(struct pci_bus *bus, int probe)
{
if (!bus->self)
Expand Down Expand Up @@ -3626,6 +3752,35 @@ int pci_reset_bus(struct pci_bus *bus)
}
EXPORT_SYMBOL_GPL(pci_reset_bus);

/**
* pci_try_reset_bus - Try to reset a PCI bus
* @bus: top level PCI bus to reset
*
* Same as above except return -EAGAIN if the bus cannot be locked
*/
int pci_try_reset_bus(struct pci_bus *bus)
{
int rc;

rc = pci_bus_reset(bus, 1);
if (rc)
return rc;

pci_bus_save_and_disable(bus);

if (pci_bus_trylock(bus)) {
might_sleep();
pci_reset_bridge_secondary_bus(bus->self);
pci_bus_unlock(bus);
} else
rc = -EAGAIN;

pci_bus_restore(bus);

return rc;
}
EXPORT_SYMBOL_GPL(pci_try_reset_bus);

/**
* pcix_get_max_mmrbc - get PCI-X maximum designed memory read byte count
* @dev: PCI device to query
Expand Down
29 changes: 9 additions & 20 deletions drivers/vfio/pci/vfio_pci.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -139,25 +139,14 @@ static void vfio_pci_disable(struct vfio_pci_device *vdev)
pci_write_config_word(pdev, PCI_COMMAND, PCI_COMMAND_INTX_DISABLE);

/*
* Careful, device_lock may already be held. This is the case if
* a driver unbind is blocked. Try to get the locks ourselves to
* prevent a deadlock.
* Try to reset the device. The success of this is dependent on
* being able to lock the device, which is not always possible.
*/
if (vdev->reset_works) {
bool reset_done = false;

if (pci_cfg_access_trylock(pdev)) {
if (device_trylock(&pdev->dev)) {
__pci_reset_function_locked(pdev);
reset_done = true;
device_unlock(&pdev->dev);
}
pci_cfg_access_unlock(pdev);
}

if (!reset_done)
pr_warn("%s: Unable to acquire locks for reset of %s\n",
__func__, dev_name(&pdev->dev));
int ret = pci_try_reset_function(pdev);
if (ret)
pr_warn("%s: Failed to reset device %s (%d)\n",
__func__, dev_name(&pdev->dev), ret);
}

pci_restore_state(pdev);
Expand Down Expand Up @@ -514,7 +503,7 @@ static long vfio_pci_ioctl(void *device_data,

} else if (cmd == VFIO_DEVICE_RESET) {
return vdev->reset_works ?
pci_reset_function(vdev->pdev) : -EINVAL;
pci_try_reset_function(vdev->pdev) : -EINVAL;

} else if (cmd == VFIO_DEVICE_GET_PCI_HOT_RESET_INFO) {
struct vfio_pci_hot_reset_info hdr;
Expand Down Expand Up @@ -684,8 +673,8 @@ static long vfio_pci_ioctl(void *device_data,
&info, slot);
if (!ret)
/* User has access, do the reset */
ret = slot ? pci_reset_slot(vdev->pdev->slot) :
pci_reset_bus(vdev->pdev->bus);
ret = slot ? pci_try_reset_slot(vdev->pdev->slot) :
pci_try_reset_bus(vdev->pdev->bus);

hot_reset_release:
for (i--; i >= 0; i--)
Expand Down
3 changes: 3 additions & 0 deletions include/linux/pci.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -949,10 +949,13 @@ int pcie_get_minimum_link(struct pci_dev *dev, enum pci_bus_speed *speed,
int __pci_reset_function(struct pci_dev *dev);
int __pci_reset_function_locked(struct pci_dev *dev);
int pci_reset_function(struct pci_dev *dev);
int pci_try_reset_function(struct pci_dev *dev);
int pci_probe_reset_slot(struct pci_slot *slot);
int pci_reset_slot(struct pci_slot *slot);
int pci_try_reset_slot(struct pci_slot *slot);
int pci_probe_reset_bus(struct pci_bus *bus);
int pci_reset_bus(struct pci_bus *bus);
int pci_try_reset_bus(struct pci_bus *bus);
void pci_reset_bridge_secondary_bus(struct pci_dev *dev);
void pci_update_resource(struct pci_dev *dev, int resno);
int __must_check pci_assign_resource(struct pci_dev *dev, int i);
Expand Down

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