c9d52fb313
While the experiment did reveal that there are additional places that are missing the lock during secondary bus reset, one of the places that needs to take cfg_access_lock (pci_bus_lock()) is not prepared for lockdep annotation. Specifically, pci_bus_lock() takes pci_dev_lock() recursively and is currently dependent on the fact that the device_lock() is marked lockdep_set_novalidate_class(&dev->mutex). Otherwise, without that annotation, pci_bus_lock() would need to use something like a new pci_dev_lock_nested() helper, a scheme to track a PCI device's depth in the topology, and a hope that the depth of a PCI tree never exceeds the max value for a lockdep subclass. The alternative to ripping out the lockdep coverage would be to deploy a dynamic lock key for every PCI device. Unfortunately, there is evidence that increasing the number of keys that lockdep needs to track to be per-PCI-device is prohibitively expensive for something like the cfg_access_lock. The main motivation for adding the annotation in the first place was to catch unlocked secondary bus resets, not necessarily catch lock ordering problems between cfg_access_lock and other locks. Solve that narrower problem with follow-on patches, and just due to targeted revert for now. Link: https://lore.kernel.org/r/171711746402.1628941.14575335981264103013.stgit@dwillia2-xfh.jf.intel.com Fixes: 7e89efc6e9e4 ("PCI: Lock upstream bridge for pci_reset_function()") Reported-by: Imre Deak <imre.deak@intel.com> Closes: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_134186v1/shard-dg2-1/igt@device_reset@unbind-reset-rebind.html Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Tested-by: Hans de Goede <hdegoede@redhat.com> Tested-by: Kalle Valo <kvalo@kernel.org> Reviewed-by: Dave Jiang <dave.jiang@intel.com> Cc: Jani Saarinen <jani.saarinen@intel.com> |
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|---|---|---|
| .. | ||
| controller | ||
| endpoint | ||
| hotplug | ||
| msi | ||
| pcie | ||
| switch | ||
| access.c | ||
| ats.c | ||
| bus.c | ||
| devres.c | ||
| doe.c | ||
| ecam.c | ||
| host-bridge.c | ||
| iomap.c | ||
| iov.c | ||
| irq.c | ||
| Kconfig | ||
| Makefile | ||
| mmap.c | ||
| of_property.c | ||
| of.c | ||
| p2pdma.c | ||
| pci-acpi.c | ||
| pci-bridge-emul.c | ||
| pci-bridge-emul.h | ||
| pci-driver.c | ||
| pci-label.c | ||
| pci-mid.c | ||
| pci-pf-stub.c | ||
| pci-stub.c | ||
| pci-sysfs.c | ||
| pci.c | ||
| pci.h | ||
| probe.c | ||
| proc.c | ||
| quirks.c | ||
| remove.c | ||
| rom.c | ||
| search.c | ||
| setup-bus.c | ||
| setup-res.c | ||
| slot.c | ||
| syscall.c | ||
| vc.c | ||
| vgaarb.c | ||
| vpd.c | ||
| xen-pcifront.c | ||