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PCI: Avoid pci_dev_lock() AB/BA deadlock with sriov_numvfs_store()
[ Upstream commit a91ee0e9fc
]
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>
This commit is contained in:
parent
5f4367448f
commit
ea047f5117
1 changed files with 5 additions and 5 deletions
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@ -5113,19 +5113,19 @@ static int pci_reset_bus_function(struct pci_dev *dev, bool probe)
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void pci_dev_lock(struct pci_dev *dev)
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{
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pci_cfg_access_lock(dev);
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/* block PM suspend, driver probe, etc. */
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device_lock(&dev->dev);
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pci_cfg_access_lock(dev);
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}
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EXPORT_SYMBOL_GPL(pci_dev_lock);
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/* Return 1 on successful lock, 0 on contention */
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int pci_dev_trylock(struct pci_dev *dev)
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{
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if (pci_cfg_access_trylock(dev)) {
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if (device_trylock(&dev->dev))
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if (device_trylock(&dev->dev)) {
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if (pci_cfg_access_trylock(dev))
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return 1;
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pci_cfg_access_unlock(dev);
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device_unlock(&dev->dev);
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}
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return 0;
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@ -5134,8 +5134,8 @@ EXPORT_SYMBOL_GPL(pci_dev_trylock);
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void pci_dev_unlock(struct pci_dev *dev)
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{
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device_unlock(&dev->dev);
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pci_cfg_access_unlock(dev);
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device_unlock(&dev->dev);
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}
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EXPORT_SYMBOL_GPL(pci_dev_unlock);
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