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Sudeep Holla 31405510a4 firmware: arm_ffa: Replace mutex with rwlock to avoid sleep in atomic context 
commit 9ca7a42122 upstream.

The current use of a mutex to protect the notifier hashtable accesses
can lead to issues in the atomic context. It results in the below
kernel warnings:

  |  BUG: sleeping function called from invalid context at kernel/locking/mutex.c:258
  |  in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 9, name: kworker/0:0
  |  preempt_count: 1, expected: 0
  |  RCU nest depth: 0, expected: 0
  |  CPU: 0 UID: 0 PID: 9 Comm: kworker/0:0 Not tainted 6.14.0 #4
  |  Workqueue: ffa_pcpu_irq_notification notif_pcpu_irq_work_fn
  |  Call trace:
  |   show_stack+0x18/0x24 (C)
  |   dump_stack_lvl+0x78/0x90
  |   dump_stack+0x18/0x24
  |   __might_resched+0x114/0x170
  |   __might_sleep+0x48/0x98
  |   mutex_lock+0x24/0x80
  |   handle_notif_callbacks+0x54/0xe0
  |   notif_get_and_handle+0x40/0x88
  |   generic_exec_single+0x80/0xc0
  |   smp_call_function_single+0xfc/0x1a0
  |   notif_pcpu_irq_work_fn+0x2c/0x38
  |   process_one_work+0x14c/0x2b4
  |   worker_thread+0x2e4/0x3e0
  |   kthread+0x13c/0x210
  |   ret_from_fork+0x10/0x20

To address this, replace the mutex with an rwlock to protect the notifier
hashtable accesses. This ensures that read-side locking does not sleep and
multiple readers can acquire the lock concurrently, avoiding unnecessary
contention and potential deadlocks. Writer access remains exclusive,
preserving correctness.

This change resolves warnings from lockdep about potential sleep in
atomic context.

Cc: Jens Wiklander <jens.wiklander@linaro.org>
Reported-by: Jérôme Forissier <jerome.forissier@linaro.org>
Closes: https://github.com/OP-TEE/optee_os/issues/7394
Fixes: e0573444ed ("firmware: arm_ffa: Add interfaces to request notification callbacks")
Message-Id: <20250528-ffa_notif_fix-v1-3-5ed7bc7f8437@arm.com>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
Tested-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2025-07-10 16:04:44 +02:00
arch s390/pci: Do not try re-enabling load/store if device is disabled 2025-07-10 16:04:41 +02:00
block block: Clear BIO_EMULATES_ZONE_APPEND flag on BIO completion 2025-06-27 11:11:19 +01:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto crypto: api - Redo lookup on EEXIST 2025-06-19 15:31:30 +02:00
Documentation dt-bindings: serial: 8250: Make clocks and clock-frequency exclusive 2025-07-06 11:01:43 +02:00
drivers firmware: arm_ffa: Replace mutex with rwlock to avoid sleep in atomic context 2025-07-10 16:04:44 +02:00
fs btrfs: fix use-after-free on inode when scanning root during em shrinking 2025-07-06 11:01:50 +02:00
include usb: typec: altmodes/displayport: do not index invalid pin_assignments 2025-07-10 16:04:43 +02:00
init rust: clean Rust 1.88.0's unnecessary_transmutes lint 2025-05-18 08:24:51 +02:00
io_uring io_uring/kbuf: flag partial buffer mappings 2025-07-06 11:01:48 +02:00
ipc ipc: fix to protect IPCS lookups using RCU 2025-06-27 11:11:22 +01:00
kernel perf/core: Fix WARN in perf_cgroup_switch() 2025-06-27 11:11:45 +01:00
lib maple_tree: fix MA_STATE_PREALLOC flag in mas_preallocate() 2025-07-06 11:01:43 +02:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm mm/vma: reset VMA iterator on commit_merge() OOM failure 2025-07-06 11:01:48 +02:00
net Bluetooth: MGMT: mesh_send: check instances prior disabling advertising 2025-07-10 16:04:43 +02:00
rust rust: arm: fix unknown (to Clang) argument '-mno-fdpic' 2025-07-06 11:01:33 +02:00
samples samples/bpf: Fix compilation failure for samples/bpf on LoongArch Fedora 2025-05-29 11:02:01 +02:00
scripts rust: compile libcore with edition 2024 for 1.87+ 2025-06-27 11:11:40 +01:00
security selinux: fix selinux_xfrm_alloc_user() to set correct ctx_len 2025-06-27 11:11:38 +01:00
sound ALSA: hda/realtek: Bass speaker fixup for ASUS UM5606KA 2025-07-06 11:01:50 +02:00
tools iommufd/selftest: Fix iommufd_dirty_tracking with large hugepage sizes 2025-07-10 16:04:43 +02:00
usr kbuild: hdrcheck: fix cross build with clang 2025-03-13 13:02:18 +01:00
virt KVM: Add member to struct kvm_gfn_range to indicate private/shared 2025-05-22 14:29:36 +02:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-18 08:24:51 +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 Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore rust: introduce .clippy.toml 2025-03-13 13:01:42 +01:00
.mailmap mailmap: add entry for Thorsten Blum 2024-11-07 14:14:59 -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: Remove self from DSA entry 2024-11-03 12:52:38 -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 MAINTAINERS: Update Alexey Makhalov's email address 2025-05-22 14:29:46 +02:00
Makefile Linux 6.12.36 2025-07-06 11:01:50 +02:00
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.