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Manivannan Sadhasivam b458ff7e81
PCI/pwrctl: Ensure that pwrctl drivers are probed before PCI client drivers
As per the kernel device driver model, a pwrctl device is the supplier for
the PCI device, but the device link that enforces the supplier-consumer
relationship was previously created by the pwrctl driver. Therefore, the
driver model didn't prevent probing PCI client drivers before probing the
corresponding pwrctl drivers. This may lead to a race condition if the PCI
device was already powered on by the bootloader (before the pwrctl driver).

If the bootloader did not power on the PCI device, this wouldn't create any
problem as the pwrctl driver will be the one powering on the device, so the
PCI client driver always gets probed afterward. But if the device was
already powered on, then the device will be seen by the PCI core and the
PCI client driver may get probed before its pwrctl driver. This creates a
race condition as the pwrctl driver may change the device power state while
the device is being accessed by the client driver.

One such issue was already reported on the Qcom X13s platform with the WLAN
device and fixed with a hack in the WCN pwrseq driver by a9aaf1ff88
("power: sequencing: request the WLAN enable GPIO as-is").

A cleaner way to fix the above mentioned race condition is to ensure that
the pwrctl drivers are always probed before the client drivers.

If the PCI device is associated with a pwrctl platform device with a power
supply, add a device link between the PCI device and the pwrctl device
before device_attach() in pci_bus_add_device().

Note that there is no need to explicitly remove the device link as that
will be taken care of by the driver core when the PCI device gets removed.

Fixes: 4565d2652a ("PCI/pwrctl: Add PCI power control core code")
Fixes: 8fb18619d9 ("PCI/pwrctl: Create platform devices for child OF nodes of the port node")
Link: https://lore.kernel.org/r/20241025-pci-pwrctl-rework-v2-3-568756156cbe@linaro.org
Tested-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Tested-by: Krishna chaitanya chundru <quic_krichai@quicinc.com>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
[bhelgaas: squash fix from
https://lore.kernel.org/r/20241120062459.6371-1-manivannan.sadhasivam@linaro.org
for SPARCv9 issue reported by Jonathan Currier <dullfire@yahoo.com>]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
[kwilczynski: wrap code to 80 columns]
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Cc: stable+noautosel@kernel.org		# Depends on power supply check
2024-11-21 16:01:13 +00:00
arch x86: kvm: fix build error 2024-09-29 14:47:33 -07:00
block for-6.12/block-20240925 2024-09-25 14:56:40 -07:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto KEYS: prevent NULL pointer dereference in find_asymmetric_key() 2024-09-20 19:49:49 +03:00
Documentation mhu-v3, omap2+ : fix kconfig dependencies 2024-09-29 09:53:04 -07:00
drivers PCI/pwrctl: Ensure that pwrctl drivers are probed before PCI client drivers 2024-11-21 16:01:13 +00:00
fs bcachefs fixes for 6.11-rc1 2024-09-29 09:17:44 -07:00
include dma-mapping fixes for Linux 6.12 2024-09-29 09:35:10 -07:00
init Rust changes for v6.12 2024-09-25 10:25:40 -07:00
io_uring for-6.12/io_uring-20240922 2024-09-24 11:11:38 -07:00
ipc struct fd layout change (and conversion to accessor helpers) 2024-09-23 09:35:36 -07:00
kernel Locking changes for v6.12: 2024-09-29 08:51:30 -07:00
lib bitmap-for-6.12 2024-09-27 12:10:45 -07:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm 19 hotfixes. 13 are cc:stable. 2024-09-27 10:27:22 -07:00
net Three CephFS fixes from Xiubo and Luis and a bunch of assorted 2024-09-28 08:40:36 -07:00
rust Rust changes for v6.12 2024-09-25 10:25:40 -07:00
samples [tree-wide] finally take no_llseek out 2024-09-27 08:18:43 -07:00
scripts Reduce Coccinelle choices in string_choices.cocci 2024-09-28 21:33:11 +02:00
security One bugfix patch, one preparation patch, and one conversion patch. 2024-09-27 12:03:48 -07:00
sound [tree-wide] finally take no_llseek out 2024-09-27 08:18:43 -07:00
tools linux_kselftest-next-6.12-rc1-fixes 2024-09-29 08:37:03 -07:00
usr initramfs: shorten cmd_initfs in usr/Makefile 2024-07-16 01:07:52 +09:00
virt x86: 2024-09-28 09:20:14 -07:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.cocciconfig
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Kbuild updates for v6.12 2024-09-24 13:02:06 -07:00
.mailmap Summary 2024-09-24 11:08:40 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Mark powerpc spufs as orphaned 2024-08-19 21:27:56 +10:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Modules changes for v6.12-rc1 2024-09-28 09:06:15 -07:00
Makefile Linux 6.12-rc1 2024-09-29 15:06:19 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

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.