From b014e96d1abbd67404bbe2018937b46466299e9e Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Thu, 1 Jun 2017 13:10:37 +0200 Subject: [PATCH] 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 : http://lkml.kernel.org/r/20170701135323.x5vaj4e2wcs2mcro@mwanda] Link: http://lkml.kernel.org/r/20170601111039.8913-2-hch@lst.de Reported-by: Rakesh Pandit Tested-by: Rakesh Pandit Signed-off-by: Christoph Hellwig Signed-off-by: Bjorn Helgaas --- 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 3b38e98e68df..f4587f6f8739 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -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)) { - 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); @@ -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); } -- 2.39.2