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Nam Cao 1883332bf2 irqchip/sifive-plic: Fix frozen interrupt due to affinity setting
[ Upstream commit 1072020685 ]

PLIC ignores interrupt completion message for disabled interrupt, explained
by the specification:

    The PLIC signals it has completed executing an interrupt handler by
    writing the interrupt ID it received from the claim to the
    claim/complete register. The PLIC does not check whether the completion
    ID is the same as the last claim ID for that target. If the completion
    ID does not match an interrupt source that is currently enabled for
    the target, the completion is silently ignored.

This caused problems in the past, because an interrupt can be disabled
while still being handled and plic_irq_eoi() had no effect. That was fixed
by checking if the interrupt is disabled, and if so enable it, before
sending the completion message. That check is done with irqd_irq_disabled().

However, that is not sufficient because the enable bit for the handling
hart can be zero despite irqd_irq_disabled(d) being false. This can happen
when affinity setting is changed while a hart is still handling the
interrupt.

This problem is easily reproducible by dumping a large file to uart (which
generates lots of interrupts) and at the same time keep changing the uart
interrupt's affinity setting. The uart port becomes frozen almost
instantaneously.

Fix this by checking PLIC's enable bit instead of irqd_irq_disabled().

Fixes: cc9f04f9a8 ("irqchip/sifive-plic: Implement irq_set_affinity() for SMP host")
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260212114125.3148067-1-namcao@linutronix.de
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2026-03-12 07:09:09 -04:00
arch KVM: arm64: Fix ID register initialization for non-protected pKVM guests 2026-03-12 07:09:08 -04:00
block block: decouple secure erase size limit from discard size limit 2026-03-04 07:19:38 -05:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: authencesn - reject too-short AAD (assoclen<8) to match ESP/ESN spec 2026-01-30 10:32:12 +01:00
Documentation ipv6: Move ipv6_fl_list from ipv6_pinfo to inet_sock. 2026-03-04 07:20:44 -05:00
drivers irqchip/sifive-plic: Fix frozen interrupt due to affinity setting 2026-03-12 07:09:09 -04:00
fs xfs: fix copy-paste error in previous fix 2026-03-04 07:21:36 -05:00
include drm/fourcc: fix plane order for 10/12/16-bit YCbCr formats 2026-03-12 07:09:09 -04:00
init printk changes for 6.18 2025-10-04 11:13:11 -07:00
io_uring io_uring/zcrx: fix user_ref race between scrub and refill paths 2026-03-04 07:21:33 -05:00
ipc ipc: don't audit capability check in ipc_permissions() 2026-02-26 14:59:19 -08:00
kernel perf/core: Fix refcount bug and potential UAF in perf_mmap 2026-03-12 07:09:07 -04:00
lib debugobject: Make it work with deferred page initialization - again 2026-03-12 07:09:08 -04:00
LICENSES LICENSES: Replace the obsolete address of the FSF in the GFDL-1.2 2025-07-24 11:15:39 +02:00
mm mm: numa_memblks: Identify the accurate NUMA ID of CFMW 2026-03-04 07:21:31 -05:00
net net: nfc: nci: Fix parameter validation for packet data 2026-03-04 07:21:34 -05:00
rust rust: list: Add unsafe blocks for container_of and safety comments 2026-03-04 07:21:35 -05:00
samples samples/ftrace: Adjust LoongArch register restore order in direct calls 2026-01-08 10:17:11 +01:00
scripts kbuild: rpm-pkg: Disable automatic requires for manual debuginfo package 2026-03-04 07:21:32 -05:00
security ima: verify the previous kernel's IMA buffer lies in addressable RAM 2026-03-04 07:21:17 -05:00
sound ALSA: pcm: Revert bufs move in snd_pcm_xfern_frames_ioctl() 2026-03-04 07:21:35 -05:00
tools tools: Fix bitfield dependency failure 2026-03-04 07:21:19 -05:00
usr gen_init_cpio: Ignore fsync() returning EINVAL on pipes 2025-10-07 09:53:05 -07:00
virt KVM: Don't clobber irqfd routing type when deassigning irqfd 2026-02-11 13:41:44 +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 6.18.16 2026-03-04 07:25:12 -05:00
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.