diff options
| author | Marco Elver <elver@google.com> | 2024-05-02 16:12:17 +0200 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2024-05-07 11:39:50 -0700 |
| commit | 31f605a308e627f06e4e6ab77254473f1c90f0bf (patch) | |
| tree | 40f60c986dd9199d0c12cc967206130237cca3aa /Documentation | |
| parent | 39cd87c4eb2b893354f3b850f916353f2658ae6f (diff) | |
kcsan, compiler_types: Introduce __data_racy type qualifier
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>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/dev-tools/kcsan.rst | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/Documentation/dev-tools/kcsan.rst b/Documentation/dev-tools/kcsan.rst index 94b6802ab0ab..02143f060b22 100644 --- a/Documentation/dev-tools/kcsan.rst +++ b/Documentation/dev-tools/kcsan.rst @@ -91,6 +91,16 @@ the below options are available: behaviour when encountering a data race is deemed safe. Please see `"Marking Shared-Memory Accesses" in the LKMM`_ for more information. +* Similar to ``data_race(...)``, the type qualifier ``__data_racy`` can be used + to document that all data races due to accesses to a variable are intended + and should be ignored by KCSAN:: + + struct foo { + ... + int __data_racy stats_counter; + ... + }; + * Disabling data race detection for entire functions can be accomplished by using the function attribute ``__no_kcsan``:: |