linux/include
Dan Williams c9d52fb313 PCI: Revert the cfg_access_lock lockdep mechanism
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: 7e89efc6e9 ("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>
2024-06-04 12:10:05 -05:00
..
acpi The usual shower of singleton fixes and minor series all over MM, 2024-05-19 09:21:03 -07:00
asm-generic asm-generic cleanups for 6.10 2024-05-20 15:18:34 -07:00
clocksource
crypto This push fixes a bug in the new ecc P521 code as well as a buggy 2024-05-20 08:47:54 -07:00
drm drm fixes for 6.10-rc1 2024-05-24 17:28:02 -07:00
dt-bindings - Core Frameworks 2024-05-22 10:49:54 -07:00
keys Hi, 2024-05-13 10:40:15 -07:00
kunit kunit: Print last test location on fault 2024-05-06 14:22:02 -06:00
kvm Merge branch kvm-arm64/misc-6.10 into kvmarm-master/next 2024-05-08 16:41:50 +01:00
linux PCI: Revert the cfg_access_lock lockdep mechanism 2024-06-04 12:10:05 -05:00
math-emu
media media: cec.h: Fix kerneldoc 2024-05-04 10:19:59 +02:00
memory
misc
net more s390 updates for 6.10 merge window 2024-05-21 12:09:36 -07:00
pcmcia
ras tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
rdma The usual shower of singleton fixes and minor series all over MM, 2024-05-19 09:21:03 -07:00
rv
scsi SCSI misc on 20240514 2024-05-14 18:25:53 -07:00
soc I'm actually surprised this time. There aren't any new Qualcomm SoC clk 2024-05-18 12:48:37 -07:00
sound ASoC: Fixes for v6.10 2024-05-23 13:29:27 +02:00
target
trace block-6.10-20240523 2024-05-23 13:44:47 -07:00
uapi drm fixes for 6.10-rc1 2024-05-24 17:28:02 -07:00
ufs
vdso
video
xen