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Lukas Wunner 382895a288 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 10:16:57 +01:00
arch powerpc/tools: drop -o pipefail in gcc check scripts 2026-01-08 10:16:44 +01:00
block block: handle zone management operations completions 2026-01-08 10:16:52 +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 10:16:43 +01:00
Documentation dt-bindings: PCI: qcom,pcie-sm8550: Add missing required power-domains and resets 2026-01-02 12:57:27 +01:00
drivers PCI/PM: Reinstate clearing state_saved in legacy and !PM codepaths 2026-01-08 10:16:57 +01:00
fs ntfs: Do not overwrite uptodate pages 2026-01-08 10:16:52 +01:00
include kunit: Enforce task execution in {soft,hard}irq contexts 2026-01-08 10:16:50 +01:00
init printk changes for 6.18 2025-10-04 11:13:11 -07:00
io_uring io_uring/rsrc: fix lost entries after cloned range 2026-01-02 12:57:30 +01:00
ipc namespace-6.18-rc1 2025-09-29 11:20:29 -07:00
kernel fgraph: Check ftrace_pids_enabled on registration for early filtering 2026-01-08 10:16:57 +01:00
lib lib/crypto: riscv: Depend on RISCV_EFFICIENT_VECTOR_UNALIGNED_ACCESS 2026-01-02 12:57:29 +01:00
LICENSES LICENSES: Replace the obsolete address of the FSF in the GFDL-1.2 2025-07-24 11:15:39 +02:00
mm mm/huge_memory: merge uniform_split_supported() and non_uniform_split_supported() 2026-01-08 10:16:41 +01:00
net ipv6: fix a BUG in rt6_get_pcpu_route() under PREEMPT_RT 2026-01-08 10:16:49 +01:00
rust rust: io: add typedef for phys_addr_t 2026-01-02 12:57:05 +01:00
samples samples: rust: fix endianness issue in rust_driver_pci 2026-01-02 12:57:05 +01:00
scripts mcb: Add missing modpost build support 2026-01-08 10:16:47 +01:00
security tpm2-sessions: Fix out of range indexing in name_size 2026-01-02 12:57:11 +01:00
sound ASoC: qcom: qdsp6: q6asm-dai: set 10 ms period and buffer alignment. 2026-01-08 10:16:54 +01:00
tools selftests/ftrace: traceonoff_triggers: strip off names 2026-01-08 10:16:52 +01:00
usr gen_init_cpio: Ignore fsync() returning EINVAL on pipes 2025-10-07 09:53:05 -07:00
virt KVM: Fix last_boosted_vcpu index assignment bug 2026-01-02 12:57:21 +01:00
.clang-format memblock: drop for_each_free_mem_pfn_range_in_zone_from() 2025-09-14 08:49:03 +03:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-07 00:11:47 +02:00
.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 MAINTAINERS: remove Alyssa Rosenzweig 2025-09-18 21:17:31 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore .gitignore: ignore compile_commands.json globally 2025-08-12 15:53:55 -07:00
.mailmap 8 hotfixes. 4 are cc:stable, 7 are against mm/. 2025-11-26 12:38:05 -08:00
.pylintrc tools: docs: parse-headers.py: move it from sphinx dir 2025-08-29 15:54:42 -06:00
.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 ISDN subsystem as orphan 2025-10-27 17:49:45 -07:00
Kbuild sched: Make migrate_{en,dis}able() inline 2025-09-25 09:57:16 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS soc: fixes for 6.18, part 4 2025-11-28 09:57:31 -08:00
Makefile Linux 6.18.3 2026-01-02 12:57:31 +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.