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If a PCI device has an associated device_node with power supplies,
pci_bus_add_device() creates platform devices for use by pwrctrl. When the
PCI device is removed, pci_stop_dev() uses of_find_device_by_node() to
locate the related platform device, then unregisters it.
But when we remove a PCI device with no associated device node,
dev_of_node(dev) is NULL, and of_find_device_by_node(NULL) returns the
first device with "dev->of_node == NULL". The result is that we (a)
mistakenly unregister a completely unrelated platform device, leading to
issues like the first trace below, and (b) dereference the NULL pointer
from dev_of_node() when clearing OF_POPULATED, as in the second trace.
Unregister a platform device only if there is one associated with this PCI
device. This resolves issues seen when doing:
# echo 1 > /sys/bus/pci/devices/.../remove
Sample issue from unregistering the wrong platform device:
WARNING: CPU: 0 PID: 5095 at drivers/regulator/core.c:5885 regulator_unregister+0x140/0x160
Call trace:
regulator_unregister+0x140/0x160
devm_rdev_release+0x1c/0x30
release_nodes+0x68/0x100
devres_release_all+0x98/0xf8
device_unbind_cleanup+0x20/0x70
device_release_driver_internal+0x1f4/0x240
device_release_driver+0x20/0x40
bus_remove_device+0xd8/0x170
device_del+0x154/0x380
device_unregister+0x28/0x88
of_device_unregister+0x1c/0x30
pci_stop_bus_device+0x154/0x1b0
pci_stop_and_remove_bus_device_locked+0x28/0x48
remove_store+0xa0/0xb8
dev_attr_store+0x20/0x40
sysfs_kf_write+0x4c/0x68
Later NULL pointer dereference for of_node_clear_flag(NULL, OF_POPULATED):
Unable to handle kernel NULL pointer dereference at virtual address 00000000000000c0
Call trace:
pci_stop_bus_device+0x190/0x1b0
pci_stop_and_remove_bus_device_locked+0x28/0x48
remove_store+0xa0/0xb8
dev_attr_store+0x20/0x40
sysfs_kf_write+0x4c/0x68
Link: https://lore.kernel.org/r/20241126210443.4052876-1-briannorris@chromium.org
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.