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9ca7a42122
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:
|
History
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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.