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Junjie Cao 935e6872db gpio: pch: use raw_spinlock_t for the register lock 
[ Upstream commit a02b8950d6 ]

pch_irq_type() is registered as the irq_chip .irq_set_type callback and
takes chip->spinlock with spin_lock_irqsave().  This callback is reached
from __setup_irq() -> __irq_set_trigger() -> chip->irq_set_type() while
the caller holds desc->lock, a raw_spinlock_t, with hardirqs disabled.
That context is not sleepable, but on PREEMPT_RT a regular spinlock_t is
an rtmutex-backed sleeping lock, so acquiring it there is invalid.

This was confirmed on a PREEMPT_RT kernel with lockdep
(PROVE_RAW_LOCK_NESTING and DEBUG_ATOMIC_SLEEP).  A grounded PoC mirrored
pch_irq_type()'s locking and drove it through the real genirq carrier
irq_set_irq_type() -> __irq_set_trigger() -> chip->irq_set_type(), i.e.
the same __irq_set_trigger() edge that __setup_irq() takes for a
requested IRQ.  With the original spin_lock_irqsave() edge lockdep
reported an invalid wait context, immediately followed by:

  BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48
  in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 95, name: insmod
  hardirqs last disabled at (3784): _raw_spin_lock_irqsave+0x4f/0x60
   rt_spin_lock+0x3a/0x1c0
   repro_irq_set_type+0x64/0xa0 [pch_repro]
   __irq_set_trigger+0x69/0x140
   irq_set_irq_type+0x78/0xd0

Switching the mirrored lock to raw_spinlock_t made both splats go away.

Convert the register lock to raw_spinlock_t.  The same lock also
serializes the GPIO direction/value callbacks and the suspend/resume
register save/restore, but all of those critical sections only perform
MMIO register accesses (ioread32()/iowrite32()) and
irq_set_handler_locked(); none of them contain sleepable operations.
Keeping this register lock non-sleeping is therefore appropriate for the
irqchip callbacks and does not change the GPIO-side locking contract.

This is the same class of issue and fix as recently addressed for other
GPIO controllers, e.g. commit 286533cb14 ("gpio: sch: use raw_spinlock_t
in the irq startup path") and commit 90f0109019 ("gpio: eic-sprd: use
raw_spinlock_t in the irq startup path").

Fixes: 38eb18a6f9 ("gpio-pch: Support interrupt function")
Cc: stable@vger.kernel.org
Signed-off-by: Junjie Cao <junjie.cao@intel.com>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Link: https://patch.msgid.link/20260723014129.1129730-1-junjie.cao@intel.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
(cherry picked from commit a02b8950d6)
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2026-08-19 17:14:12 +02:00
arch um: vector: fix use-after-free in vector_mmsg_rx() 2026-08-19 17:14:10 +02:00
block partitions: aix: bound the pp_count scan to the ppe array 2026-07-24 15:51:24 +02:00
certs X.509: Fix validation of ASN.1 certificate header 2026-07-24 15:51:59 +02:00
crypto crypto: rsa-pkcs1pad: Don't WARN on an empty digest 2026-08-19 17:13:55 +02:00
Documentation PCI: Move Resizable BAR code to rebar.c 2026-07-24 15:51:58 +02:00
drivers gpio: pch: use raw_spinlock_t for the register lock 2026-08-19 17:14:12 +02:00
fs binfmt_misc: reject a flag character as the field delimiter 2026-08-19 17:14:10 +02:00
include dmaengine: qcom: bam_dma: Fix command element mask field for BAM v1.6.0+ 2026-08-19 17:14:09 +02:00
init randomize_kstack: Maintain kstack_offset per task 2026-06-19 13:33:41 +02:00
io_uring io_uring/io-wq: re-check IO_WQ_BIT_EXIT for each linked work item 2026-07-24 15:51:21 +02:00
ipc ipc/shm: serialize orphan cleanup with shm_nattch updates 2026-06-19 13:33:38 +02:00
kernel tracing/filters: Fix false positive match in regex_match_full() 2026-08-19 17:14:10 +02:00
lib rhashtable: clear stale iter->p on table restart 2026-08-19 17:14:08 +02:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm mm/huge_memory: unlock i_mmap_rwsem before releasing after-split folios 2026-08-19 17:14:12 +02:00
net net: openvswitch: fix skb leak on flow key update failure during recirculation 2026-08-19 17:14:12 +02:00
samples tracing/events: Fix to check the simple_tsk_fn creation 2026-07-24 15:51:42 +02:00
scripts kconfig: fix potential NULL pointer dereference in conf_askvalue 2026-07-24 15:51:28 +02:00
security keys: make keyring key-chunk byte order agree with keyring_diff_objects() 2026-08-19 17:14:06 +02:00
sound ALSA: usb-audio: Clamp frame size in implicit-feedback mode 2026-08-19 17:14:09 +02:00
tools selftests/clone3: fix wild pointer access of getline due to missing init 2026-08-19 17:14:10 +02:00
usr kbuild: hdrcheck: fix cross build with clang 2025-06-27 11:05:22 +01:00
virt KVM: Move kvm_io_bus_get_dev() locking responsibilities to callers 2026-07-24 15:52:02 +02:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Remove *.orig pattern from .gitignore 2024-10-17 15:11:10 +02:00
.mailmap mailmap: add Andrej Shadura 2021-10-18 20:22:03 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
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 06:09:36 +09:00
Makefile Linux 5.15.215 2026-08-07 08:07:31 +02:00
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.