mirror of
https://github.com/torvalds/linux
synced 2024-10-15 07:47:34 +00:00
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:
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.