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Lukas Wunner 40fa3b5201 PCI/PM: Reinstate clearing state_saved in legacy and !PM codepaths 
commit 894f475f88 upstream.

When a PCI device is suspended, it is normally the PCI core's job to save
Config Space and put the device into a low power state.  However drivers
are allowed to assume these responsibilities.  When they do, the PCI core
can tell by looking at the state_saved flag in struct pci_dev:  The flag
is cleared before commencing the suspend sequence and it is set when
pci_save_state() is called.  If the PCI core finds the flag set late in
the suspend sequence, it refrains from calling pci_save_state() itself.

But there are two corner cases where the PCI core neglects to clear the
flag before commencing the suspend sequence:

* If a driver has legacy PCI PM callbacks, pci_legacy_suspend() neglects
  to clear the flag.  The (stale) flag is subsequently queried by
  pci_legacy_suspend() itself and pci_legacy_suspend_late().

* If a device has no driver or its driver has no PCI PM callbacks,
  pci_pm_freeze() neglects to clear the flag.  The (stale) flag is
  subsequently queried by pci_pm_freeze_noirq().

The flag may be set prior to suspend if the device went through error
recovery:  Drivers commonly invoke pci_restore_state() + pci_save_state()
to restore Config Space after reset.

The flag may also be set if drivers call pci_save_state() on probe to
allow for recovery from subsequent errors.

The result is that pci_legacy_suspend_late() and pci_pm_freeze_noirq()
don't call pci_save_state() and so the state that will be restored on
resume is the one recorded on last error recovery or on probe, not the one
that the device had on suspend.  If the two states happen to be identical,
there's no problem.

Reinstate clearing the flag in pci_legacy_suspend() and pci_pm_freeze().
The two functions used to do that until commit 4b77b0a2ba ("PCI: Clear
saved_state after the state has been restored") deemed it unnecessary
because it assumed that it's sufficient to clear the flag on resume in
pci_restore_state().  The commit seemingly did not take into account that
pci_save_state() and pci_restore_state() are not only used by power
management code, but also for error recovery.

Devices without driver or whose driver has no PCI PM callbacks may be in
runtime suspend when pci_pm_freeze() is called.  Their state has already
been saved, so don't clear the flag to skip a pointless pci_save_state()
in pci_pm_freeze_noirq().

None of the drivers with legacy PCI PM callbacks seem to use runtime PM,
so clear the flag unconditionally in their case.

Fixes: 4b77b0a2ba ("PCI: Clear saved_state after the state has been restored")
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rafael J. Wysocki (Intel) <rafael@kernel.org>
Cc: stable@vger.kernel.org # v2.6.32+
Link: https://patch.msgid.link/094f2aad64418710daf0940112abe5a0afdc6bce.1763483367.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2026-01-08 10:14:41 +01:00
arch x86/msi: Make irq_retrigger() functional for posted MSI 2026-01-08 10:14:31 +01:00
block blk-mq: skip CPU offline notify on unmapped hctx 2026-01-08 10:14:37 +01:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: seqiv - Do not use req->iv after crypto_aead_encrypt 2026-01-08 10:14:32 +01:00
Documentation dt-bindings: PCI: qcom,pcie-sm8550: Add missing required power-domains and resets 2026-01-08 10:14:28 +01:00
drivers PCI/PM: Reinstate clearing state_saved in legacy and !PM codepaths 2026-01-08 10:14:41 +01:00
fs ntfs: Do not overwrite uptodate pages 2026-01-08 10:14:37 +01:00
include genalloc.h: fix htmldocs warning 2026-01-08 10:14:34 +01:00
init init: handle bootloader identifier in kernel parameters 2025-10-19 16:33:50 +02:00
io_uring io_uring: fix min_wait wakeups for SQPOLL 2026-01-08 10:14:25 +01:00
ipc ipc: fix to protect IPCS lookups using RCU 2025-06-27 11:11:22 +01:00
kernel fgraph: Check ftrace_pids_enabled on registration for early filtering 2026-01-08 10:14:41 +01:00
lib lib/vsprintf: Check pointer before dereferencing in time_and_date() 2025-12-18 13:54:57 +01:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm shmem: fix recovery on rename failures 2026-01-08 10:13:54 +01:00
net ipv6: fix a BUG in rt6_get_pcpu_route() under PREEMPT_RT 2026-01-08 10:14:35 +01:00
rust rust: kbuild: workaround rustdoc doctests modifier bug 2025-11-24 10:36:07 +01:00
samples samples: work around glibc redefining some of our defines wrong 2025-12-12 18:37:21 +01:00
scripts kbuild: fix compilation of dtb specified on command-line without make rule 2026-01-08 10:14:34 +01:00
security KEYS: trusted: Fix a memory leak in tpm2_load_cmd 2026-01-08 10:14:13 +01:00
sound ASoC: qcom: qdsp6: q6asm-dai: set 10 ms period and buffer alignment. 2026-01-08 10:14:39 +01:00
tools selftests/ftrace: traceonoff_triggers: strip off names 2026-01-08 10:14:37 +01:00
usr kbuild: uapi: Strip comments before size type check 2025-11-13 15:34:35 -05:00
virt KVM: Disallow toggling KVM_MEM_GUEST_MEMFD on an existing memslot 2026-01-08 10:14:21 +01:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.clippy.toml rust: give Clippy the minimum supported Rust version 2025-08-01 09:48:44 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.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 rust: introduce .clippy.toml 2025-03-13 13:01:42 +01:00
.mailmap mailmap: add entry for Thorsten Blum 2024-11-07 14:14:59 -08:00
.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: Remove self from DSA entry 2024-11-03 12:52:38 -08:00
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 staging: rtl8712: Remove driver using deprecated API wext 2025-12-07 06:25:02 +09:00
Makefile Linux 6.12.63 2025-12-18 13:55:23 +01:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

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.