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Commit b014e96d authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Bjorn Helgaas
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PCI: Protect pci_error_handlers->reset_notify() usage with device_lock() 

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@oracle.com>:
http://lkml.kernel.org/r/20170701135323.x5vaj4e2wcs2mcro@mwanda]
Link: http://lkml.kernel.org/r/20170601111039.8913-2-hch@lst.de


Reported-by: default avatarRakesh Pandit <rakesh@tuxera.com>
Tested-by: default avatarRakesh Pandit <rakesh@tuxera.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
parent 17530e71

drivers/pci/pci.c

+18 −8
Original line number Diff line number Diff line
@@ -4143,6 +4143,12 @@ 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);

}
@@ -4278,11 +4284,13 @@ 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;

}
@@ -4302,16 +4310,14 @@ 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)) {

	pci_dev_save_and_disable(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);
@@ -4461,7 +4467,9 @@ 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);

	}
@@ -4476,7 +4484,9 @@ 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);

	}