From: Christoph Hellwig <hch@xxxxxx>
[ Upstream commit b014e96d1abbd67404bbe2018937b46466299e9e ]
Every method in struct device_driver or structures derived from it like
struct pci_driver MUST provide exclusion vs the driver's ->remove() method,
usually by using device_lock().
Protect use of pci_error_handlers->reset_notify() by holding the device
lock while calling it.
Note:
- pci_dev_lock() calls device_lock() in addition to blocking user-space
config accesses.
- pci_err_handlers->reset_notify() is used inside
pci_dev_save_and_disable() and pci_dev_restore(). We could hold the
device lock directly in pci_reset_notify(), but we expand the region
since we have several calls following each other.
Without this, ->reset_notify() may race with ->remove() calls, which can be
easily triggered in NVMe.
[bhelgaas: changelog, add pci_reset_notify() comment]
[bhelgaas: fold in fix from Dan Carpenter <dan.carpenter@xxxxxxxxxx>:
http://lkml.kernel.org/r/20170701135323.x5vaj4e2wcs2mcro@mwanda]
Link: http://lkml.kernel.org/r/20170601111039.8913-2-hch@xxxxxx
Reported-by: Rakesh Pandit <rakesh@xxxxxxxxxx>
Tested-by: Rakesh Pandit <rakesh@xxxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
drivers/pci/pci.c | 26 ++++++++++++++++++--------
1 file changed, 18 insertions(+), 8 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 295bf1472d02..84854f522291 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -3672,6 +3672,12 @@ static void pci_reset_notify(struct pci_dev *dev, bool prepare)
{
const struct pci_error_handlers *err_handler =
dev->driver ? dev->driver->err_handler : NULL;
+
+ /*
+ * dev->driver->err_handler->reset_notify() is protected against
+ * races with ->remove() by the device lock, which must be held by
+ * the caller.
+ */
if (err_handler && err_handler->reset_notify)
err_handler->reset_notify(dev, prepare);
}
@@ -3807,11 +3813,13 @@ int pci_reset_function(struct pci_dev *dev)
if (rc)
return rc;
+ pci_dev_lock(dev);
pci_dev_save_and_disable(dev);
- rc = pci_dev_reset(dev, 0);
+ rc = __pci_dev_reset(dev, 0);
pci_dev_restore(dev);
+ pci_dev_unlock(dev);
return rc;
}
@@ -3831,16 +3839,14 @@ int pci_try_reset_function(struct pci_dev *dev)
if (rc)
return rc;
- pci_dev_save_and_disable(dev);
+ if (!pci_dev_trylock(dev))
+ return -EAGAIN;
- if (pci_dev_trylock(dev)) {
- rc = __pci_dev_reset(dev, 0);
- pci_dev_unlock(dev);
- } else
- rc = -EAGAIN;
+ pci_dev_save_and_disable(dev);
+ rc = __pci_dev_reset(dev, 0);
+ pci_dev_unlock(dev);
pci_dev_restore(dev);
-
return rc;
}
EXPORT_SYMBOL_GPL(pci_try_reset_function);
@@ -3994,7 +4000,9 @@ static void pci_bus_save_and_disable(struct pci_bus *bus)
struct pci_dev *dev;
list_for_each_entry(dev, &bus->devices, bus_list) {
+ pci_dev_lock(dev);
pci_dev_save_and_disable(dev);
+ pci_dev_unlock(dev);
if (dev->subordinate)
pci_bus_save_and_disable(dev->subordinate);
}
@@ -4009,7 +4017,9 @@ static void pci_bus_restore(struct pci_bus *bus)
struct pci_dev *dev;
list_for_each_entry(dev, &bus->devices, bus_list) {
+ pci_dev_lock(dev);
pci_dev_restore(dev);
+ pci_dev_unlock(dev);
if (dev->subordinate)
pci_bus_restore(dev->subordinate);
}
--
2.15.1