diff options
| author | Yicong Yang <yangyicong@hisilicon.com> | 2022-04-04 09:25:39 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-06-09 11:20:58 +0300 |
| commit | eff3587b9c01439b738298475e555c028ac9f55e (patch) | |
| tree | 52ec39d0d1ec33bef477bf556dc3905da121e264 /drivers/pci | |
| parent | 21a3effe446dd6dc5eed7fe897c2f9b88c9a5d6d (diff) | |
| download | linux-eff3587b9c01439b738298475e555c028ac9f55e.tar.xz | |
PCI: Avoid pci_dev_lock() AB/BA deadlock with sriov_numvfs_store()
[ Upstream commit a91ee0e9fca9d7501286cfbced9b30a33e52740a ]
The sysfs sriov_numvfs_store() path acquires the device lock before the
config space access lock:
sriov_numvfs_store
device_lock # A (1) acquire device lock
sriov_configure
vfio_pci_sriov_configure # (for example)
vfio_pci_core_sriov_configure
pci_disable_sriov
sriov_disable
pci_cfg_access_lock
pci_wait_cfg # B (4) wait for dev->block_cfg_access == 0
Previously, pci_dev_lock() acquired the config space access lock before the
device lock:
pci_dev_lock
pci_cfg_access_lock
dev->block_cfg_access = 1 # B (2) set dev->block_cfg_access = 1
device_lock # A (3) wait for device lock
Any path that uses pci_dev_lock(), e.g., pci_reset_function(), may
deadlock with sriov_numvfs_store() if the operations occur in the sequence
(1) (2) (3) (4).
Avoid the deadlock by reversing the order in pci_dev_lock() so it acquires
the device lock before the config space access lock, the same as the
sriov_numvfs_store() path.
[bhelgaas: combined and adapted commit log from Jay Zhou's independent
subsequent posting:
https://lore.kernel.org/r/20220404062539.1710-1-jianjay.zhou@huawei.com]
Link: https://lore.kernel.org/linux-pci/1583489997-17156-1-git-send-email-yangyicong@hisilicon.com/
Also-posted-by: Jay Zhou <jianjay.zhou@huawei.com>
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers/pci')
| -rw-r--r-- | drivers/pci/pci.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index cda17c615148..6ebbe06f0b08 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -4975,18 +4975,18 @@ static int pci_dev_reset_slot_function(struct pci_dev *dev, int probe) static void pci_dev_lock(struct pci_dev *dev) { - pci_cfg_access_lock(dev); /* block PM suspend, driver probe, etc. */ device_lock(&dev->dev); + pci_cfg_access_lock(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)) + if (device_trylock(&dev->dev)) { + if (pci_cfg_access_trylock(dev)) return 1; - pci_cfg_access_unlock(dev); + device_unlock(&dev->dev); } return 0; @@ -4994,8 +4994,8 @@ static int pci_dev_trylock(struct pci_dev *dev) static void pci_dev_unlock(struct pci_dev *dev) { - device_unlock(&dev->dev); pci_cfg_access_unlock(dev); + device_unlock(&dev->dev); } static void pci_dev_save_and_disable(struct pci_dev *dev) |