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Boqun Feng a155ac8f0c interrupt: Disable interrupt before modifying hardirq_disable counter
Currently a softirq may be pending longer then expected if the
triggering interrupt happens in-between hardirq_disable_enter() and
_local_interrupt_disable() in local_interrupt_disable():

    local_interrupt_disable():
      hardirq_disable_enter();
      <interrupt>
      ...
      __irq_exit_rcu():
        // false because hardirq_disable_count() is not 0
        if (.. && !hardirq_disable_count() && ..) {
	  invoke_softirq();
	}
      _local_interrupt_disable();

, it'll defer the softirq to the next interrupt which can be forever.

The order between hardirq_disable_enter() and _local_interrupt_disable()
is to optimize re-disabling interrupts if they are already disabled, but
as 1) local_interrupt_disable() is not widely used yet and 2) the proper
way to achieve this optimization may need fixing up the counter at
entry/exit time [1], so reverse the order for now to avoid the softirq
pending issue.

Because of this fix, the part of saving the current state is separated
from irq disabling, and the logic of local_interrupt_disable() becomes:

    local_irq_save(flags);
    if (counter++ == 0) {
      this_cpu(local_interrupt_disable_state) = flags;
    }

Therefore change the helper function _local_interrupt_disable() to
_local_interrupt_save_state() which only saves the current irqflags
(when interrupts get disabled the first time).

Fixes: e901c1510e ("irq,spin_lock: Add counted interrupt disabling/enabling")
Reported-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Boqun Feng <boqun@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Bradley Morgan <brads@mainlining.org>
Link: https://patch.msgid.link/20260829213412.14303-1-boqun@kernel.org
Link: https://lore.kernel.org/lkml/87v78wezid.ffs@fw13/ [1]
Closes: https://lore.kernel.org/lkml/87jypbfu1t.ffs@fw13/
History 2026-08-30 08:39:04 +02:00
arch pci-v7.3-changes 2026-08-23 12:44:10 -07:00
block for-7.3/block-20260819 2026-08-20 13:55:16 -07:00
certs treewide: fix indentation and whitespace in Kconfig files 2026-05-28 21:24:42 -07:00
crypto This update includes the following changes: 2026-08-19 17:25:42 -07:00
Documentation RCU updates: 2026-08-23 18:00:22 -07:00
drivers I3C for 7.3 2026-08-23 13:28:57 -07:00
fs EFI updates for v7.3 2026-08-23 09:24:34 -07:00
include interrupt: Disable interrupt before modifying hardirq_disable counter 2026-08-30 08:39:04 +02:00
init mm.git review status for mm-hotfixes-stable..mm-stable 2026-08-20 18:17:08 -07:00
io_uring for-7.3/block-20260819 2026-08-20 13:55:16 -07:00
ipc mm.git review status for master..mm-nonmm-stable 2026-08-23 08:07:11 -07:00
kernel interrupt: Disable interrupt before modifying hardirq_disable counter 2026-08-30 08:39:04 +02:00
lib mm.git review status for master..mm-nonmm-stable 2026-08-23 08:07:11 -07:00
LICENSES LICENSES: Add modern form of the LGPL-2.1 tags to the usage guide section 2025-10-22 07:58:19 +02:00
mm RCU updates: 2026-08-23 18:00:22 -07:00
net RDMA v7.3 merge window pull 2026-08-21 11:48:54 -07:00
rust RCU updates: 2026-08-23 18:00:22 -07:00
samples Modules changes for 7.3-rc1 2026-08-21 12:47:25 -07:00
scripts mm.git review status for master..mm-nonmm-stable 2026-08-23 08:07:11 -07:00
security Hi, 2026-08-23 08:29:33 -07:00
sound mm.git review status for mm-hotfixes-stable..mm-stable 2026-08-20 18:17:08 -07:00
tools EFI updates for v7.3 2026-08-23 09:24:34 -07:00
usr usr: Correct a spelling by changing a letter 2026-08-05 14:51:58 +02:00
virt mm: use linear_page_[index, delta]() consistently 2026-08-04 19:19:01 -07:00
.clang-format drm/bridge: rename drm_for_each_bridge_in_chain_scoped() to drm_for_each_bridge_in_chain() 2026-07-14 17:55:51 +02:00
.clippy.toml rust: bump Clippy's MSRV and clean incompatible_msrv allows 2026-04-07 09:51:39 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig editorconfig: add rst extension 2026-01-26 19:07:09 -08:00
.get_maintainer.ignore .get_maintainer.ignore: add Nathan Chancellor 2026-08-03 21:10:12 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore SPDX patches for 7.2-rc1 2026-06-22 12:06:22 -07:00
.mailmap mm.git review status for master..mm-nonmm-stable 2026-08-23 08:07:11 -07:00
.pylintrc docs: Move the python libraries to tools/lib/python 2025-11-18 09:22:40 -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 CIFS Maintainer switch 2026-08-21 12:16:31 -07:00
Kbuild checksyscalls: move instance functionality into generic code 2026-04-05 09:21:32 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS RCU updates: 2026-08-23 18:00:22 -07:00
Makefile livepatching changes for 7.3 2026-08-21 13:11:56 -07:00
README README: remove out of place emdashes 2026-07-15 10:51:29 -06:00

Linux kernel
============

The Linux kernel is the core of any Linux operating system. It manages hardware,
system resources, and provides the fundamental services for all other software.

Quick Start
-----------

* Report a bug: See Documentation/admin-guide/reporting-issues.rst
* Get the latest kernel: https://kernel.org
* Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst
* Join the community: https://lore.kernel.org/

Essential Documentation
-----------------------

All users should be familiar with:

* Building requirements: Documentation/process/changes.rst
* Code of Conduct: Documentation/process/code-of-conduct.rst
* License: See COPYING

Documentation can be built with make htmldocs or viewed online at:
https://www.kernel.org/doc/html/latest/


Who Are You?
============

Find your role below:

* New Kernel Developer: Getting started with kernel development
* Academic Researcher: Studying kernel internals and architecture
* Security Expert: Hardening and vulnerability analysis
* Backport/Maintenance Engineer: Maintaining stable kernels
* System Administrator: Configuring and troubleshooting
* Maintainer: Leading subsystems and reviewing patches
* Hardware Vendor: Writing drivers for new hardware
* Distribution Maintainer: Packaging kernels for distros
* AI Coding Assistant: LLMs and AI-powered development tools


For Specific Users
==================

New Kernel Developer
--------------------

Welcome! Start your kernel development journey here:

* Getting Started: Documentation/process/development-process.rst
* Your First Patch: Documentation/process/submitting-patches.rst
* Coding Style: Documentation/process/coding-style.rst
* Build System: Documentation/kbuild/index.rst
* Development Tools: Documentation/dev-tools/index.rst
* Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst
* Core APIs: Documentation/core-api/index.rst

Academic Researcher
-------------------

Explore the kernel's architecture and internals:

* Researcher Guidelines: Documentation/process/researcher-guidelines.rst
* Memory Management: Documentation/mm/index.rst
* Scheduler: Documentation/scheduler/index.rst
* Networking Stack: Documentation/networking/index.rst
* Filesystems: Documentation/filesystems/index.rst
* RCU (Read-Copy Update): Documentation/RCU/index.rst
* Locking Primitives: Documentation/locking/index.rst
* Power Management: Documentation/power/index.rst

Security Expert
---------------

Security documentation and hardening guides:

* Security Documentation: Documentation/security/index.rst
* LSM Development: Documentation/security/lsm-development.rst
* Self Protection: Documentation/security/self-protection.rst
* Reporting Vulnerabilities: Documentation/process/security-bugs.rst
* CVE Procedures: Documentation/process/cve.rst
* Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst
* Security Features: Documentation/userspace-api/seccomp_filter.rst

Backport/Maintenance Engineer
-----------------------------

Maintain and stabilize kernel versions:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* Backporting Guide: Documentation/process/backporting.rst
* Applying Patches: Documentation/process/applying-patches.rst
* Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git for Maintainers: Documentation/maintainer/configure-git.rst

System Administrator
--------------------

Configure, tune, and troubleshoot Linux systems:

* Admin Guide: Documentation/admin-guide/index.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst
* Tracing/Debugging: Documentation/trace/index.rst
* Performance Security: Documentation/admin-guide/perf-security.rst
* Hardware Monitoring: Documentation/hwmon/index.rst

Maintainer
----------

Lead kernel subsystems and manage contributions:

* Maintainer Handbook: Documentation/maintainer/index.rst
* Pull Requests: Documentation/maintainer/pull-requests.rst
* Managing Patches: Documentation/maintainer/modifying-patches.rst
* Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst
* Development Process: Documentation/process/maintainer-handbooks.rst
* Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git Configuration: Documentation/maintainer/configure-git.rst

Hardware Vendor
---------------

Write drivers and support new hardware:

* Driver API Guide: Documentation/driver-api/index.rst
* Driver Model: Documentation/driver-api/driver-model/driver.rst
* Device Drivers: Documentation/driver-api/infrastructure.rst
* Bus Types: Documentation/driver-api/driver-model/bus.rst
* Device Tree Bindings: Documentation/devicetree/bindings/
* Power Management: Documentation/driver-api/pm/index.rst
* DMA API: Documentation/core-api/dma-api.rst

Distribution Maintainer
-----------------------

Package and distribute the kernel:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* ABI Documentation: Documentation/ABI/README
* Kernel Configuration: Documentation/kbuild/kconfig.rst
* Module Signing: Documentation/admin-guide/module-signing.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst

AI Coding Assistant
-------------------

CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and
follow the AI coding assistants documentation before contributing to the Linux
kernel:

* Documentation/process/coding-assistants.rst

This documentation contains essential requirements about licensing, attribution,
and the Developer Certificate of Origin that all AI tools must comply with.


Communication and Support
=========================

* Mailing Lists: https://lore.kernel.org/
* IRC: #kernelnewbies on irc.oftc.net
* Bugzilla: https://bugzilla.kernel.org/
* MAINTAINERS file: Lists subsystem maintainers and mailing lists
* Email Clients: Documentation/process/email-clients.rst