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Linux kernel source tree
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The pending bit is used to avoid queueing in case the lock is uncontended, and has demonstrated benefits for the 2 contender scenario, esp. on x86. In case the pending bit is acquired and we wait for the locked bit to disappear, we may get stuck due to the lock owner not making progress. Hence, this waiting loop must be protected with a timeout check. To perform a graceful recovery once we decide to abort our lock acquisition attempt in this case, we must unset the pending bit since we own it. All waiters undoing their changes and exiting gracefully allows the lock word to be restored to the unlocked state once all participants (owner, waiters) have been recovered, and the lock remains usable. Hence, set the pending bit back to zero before returning to the caller. Introduce a lockevent (rqspinlock_lock_timeout) to capture timeout event statistics. Reviewed-by: Barret Rhoden <brho@google.com> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Link: https://lore.kernel.org/r/20250316040541.108729-10-memxor@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
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| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| 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.