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Nam Cao 9c92006b89 irqchip/sifive-plic: Enable interrupt if needed before EOI
RISC-V PLIC cannot "end-of-interrupt" (EOI) disabled interrupts, as
explained in the description of Interrupt Completion in the PLIC spec:

"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."

Commit 69ea463021 ("irqchip/sifive-plic: Fixup EOI failed when masked")
ensured that EOI is successful by enabling interrupt first, before EOI.

Commit a1706a1c50 ("irqchip/sifive-plic: Separate the enable and mask
operations") removed the interrupt enabling code from the previous
commit, because it assumes that interrupt should already be enabled at the
point of EOI.

However, this is incorrect: there is a window after a hart claiming an
interrupt and before irq_desc->lock getting acquired, interrupt can be
disabled during this window. Thus, EOI can be invoked while the interrupt
is disabled, effectively nullify this EOI. This results in the interrupt
never gets asserted again, and the device who uses this interrupt appears
frozen.

Make sure that interrupt is really enabled before EOI.

Fixes: a1706a1c50 ("irqchip/sifive-plic: Separate the enable and mask operations")
Signed-off-by: Nam Cao <namcao@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Samuel Holland <samuel@sholland.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: linux-riscv@lists.infradead.org
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20240131081933.144512-1-namcao@linutronix.de
2024-02-19 15:05:18 +01:00
Documentation Kbuild fixes for v6.8 (2nd) 2024-02-18 10:09:25 -08:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
arch Kbuild fixes for v6.8 (2nd) 2024-02-18 10:09:25 -08:00
block blk-iocost: Fix an UBSAN shift-out-of-bounds warning 2024-02-08 10:11:39 -07:00
certs This update includes the following changes: 2023-11-02 16:15:30 -10:00
crypto crypto: algif_hash - Remove bogus SGL free on zero-length error path 2024-02-02 18:08:12 +08:00
drivers irqchip/sifive-plic: Enable interrupt if needed before EOI 2024-02-19 15:05:18 +01:00
fs bcachefs fixes for v6.8-rc5 2024-02-17 13:17:32 -08:00
include Char/Misc changes for 6.8-rc5 2024-02-17 08:52:38 -08:00
init update workarounds for gcc "asm goto" issue 2024-02-15 11:14:33 -08:00
io_uring io_uring/net: fix multishot accept overflow handling 2024-02-14 18:30:19 -07:00
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kernel Probes fixes for v6.8-rc4: 2024-02-17 07:59:47 -08:00
lib Driver core fixes for 6.8-rc5 2024-02-17 08:56:41 -08:00
mm mm/memory: Use exception ip to search exception tables 2024-02-12 23:04:42 +01:00
net Including fixes from can, wireless and netfilter. 2024-02-15 11:39:27 -08:00
rust Rust changes for v6.8 2024-01-11 13:05:41 -08:00
samples work around gcc bugs with 'asm goto' with outputs 2024-02-09 15:57:48 -08:00
scripts kallsyms: ignore ARMv4 thunks along with others 2024-02-15 22:44:56 +09:00
security lsm/stable-6.8 PR 20240215 2024-02-16 07:58:43 -08:00
sound ALSA: usb-audio: More relaxed check of MIDI jack names 2024-02-15 16:56:05 +01:00
tools powerpc fixes for 6.8 #3 2024-02-17 16:59:31 -08:00
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virt Generic: 2024-01-17 13:03:37 -08:00
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.cocciconfig
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.mailmap Including fixes from can, wireless and netfilter. 2024-02-15 11:39:27 -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: supplement of zswap maintainers update 2024-01-25 23:52:21 -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 Driver core fixes for 6.8-rc5 2024-02-17 08:56:41 -08:00
Makefile Linux 6.8-rc5 2024-02-18 12:56:25 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -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 Restructured Text 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.