From: Christoph Hellwig hch@lst.de
[ 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@oracle.com: http://lkml.kernel.org/r/20170701135323.x5vaj4e2wcs2mcro@mwanda] Link: http://lkml.kernel.org/r/20170601111039.8913-2-hch@lst.de Reported-by: Rakesh Pandit rakesh@tuxera.com Tested-by: Rakesh Pandit rakesh@tuxera.com Signed-off-by: Christoph Hellwig hch@lst.de Signed-off-by: Bjorn Helgaas bhelgaas@google.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- 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 a87c8e1aef68..774b0e2d117b 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -4036,6 +4036,12 @@ 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); } @@ -4171,11 +4177,13 @@ 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; } @@ -4195,16 +4203,14 @@ 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); @@ -4358,7 +4364,9 @@ 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); } @@ -4373,7 +4381,9 @@ 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); }