Kumar Kartikeya Dwivedi 5860f5ce47 rqspinlock: Perform AA checks immediately
Currently, while we enter the check_timeout call immediately due to the
way the ts.spin is initialized, we still invoke the AA and ABBA checks
in the second invocation, and only initialize the timestamp in the first
one. Since each iteration is at least done with a 1ms delay, this can
add delays in detection of AA deadlocks, up to a ms.

Rework check_timeout() to avoid this. First, call check_deadlock_AA()
while initializing the timestamps for the wait period. This also means
that we only do it once per waiting period, instead of every invocation.
Finally, drop check_deadlock() and call check_deadlock_ABBA() directly.

To save on unnecessary ktime_get_mono_fast_ns() in case of AA deadlock,
sample the time only if it returns 0.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20251128232802.1031906-3-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2025-11-29 09:35:35 -08:00
2025-11-28 15:20:16 -08:00
2022-09-28 09:02:20 +02:00
2025-02-19 14:53:27 -07:00
2025-11-09 15:10:19 -08:00
2024-03-18 03:36:32 -06:00

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.
Description
Linux kernel source tree
Readme 8.3 GiB
Languages
C 97.1%
Assembly 1%
Shell 0.6%
Rust 0.4%
Python 0.4%
Other 0.3%