31f605a308
Based on the discussion at [1], it would be helpful to mark certain
variables as explicitly "data racy", which would result in KCSAN not
reporting data races involving any accesses on such variables. To do
that, introduce the __data_racy type qualifier:
struct foo {
...
int __data_racy bar;
...
};
In KCSAN-kernels, __data_racy turns into volatile, which KCSAN already
treats specially by considering them "marked". In non-KCSAN kernels the
type qualifier turns into no-op.
The generated code between KCSAN-instrumented kernels and non-KCSAN
kernels is already huge (inserted calls into runtime for every memory
access), so the extra generated code (if any) due to volatile for few
such __data_racy variables are unlikely to have measurable impact on
performance.
Link: https://lore.kernel.org/all/CAHk-=wi3iondeh_9V2g3Qz5oHTRjLsOpoy83hb58MVh=nRZe0A@mail.gmail.com/ [1]
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Marco Elver <elver@google.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Paul E. McKenney <paulmck@kernel.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 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.