e2c12739cc
There is a possibility of deadlock if synchronize_hardirq() is called
when the nested threaded interrupt is active. The following scenario
was observed on a uniprocessor PREEMPT_NONE system:
Thread 1 Thread 2
handle_nested_thread()
Set INPROGRESS
Call ->thread_fn()
thread_fn goes to sleep
free_irq()
__synchronize_hardirq()
Busy-loop forever waiting for INPROGRESS
to be cleared
The INPROGRESS flag is only supposed to be used for hard interrupt
handlers. Remove the incorrect usage in the nested threaded interrupt
case and instead re-use the threads_active / wait_for_threads mechanism
to wait for nested threaded interrupts to complete.
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20230613-genirq-nested-v3-1-ae58221143eb@axis.com
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.