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5c9da9fe82
Improve atomic update of last_value in pvclock_clocksource_read: - Atomic update can be skipped if the "last_value" is already equal to "ret". - The detection of atomic update failure is not correct. The value, returned by atomic64_cmpxchg should be compared to the old value from the location to be updated. If these two are the same, then atomic update succeeded and "last_value" location is updated to "ret" in an atomic way. Otherwise, the atomic update failed and it should be retried with the value from "last_value" - exactly what atomic64_try_cmpxchg does in a correct and more optimal way. Signed-off-by: Uros Bizjak <ubizjak@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lkml.kernel.org/r/20230118202330.3740-1-ubizjak@gmail.com Link: https://lore.kernel.org/r/20230126151323.643408110@infradead.org
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.