Messages in this thread Patch in this message | | | Date | Tue, 31 Mar 2020 21:32:33 +0200 | Subject | [PATCH 2/2] kcsan: Change data_race() to no longer require marking racing accesses | From | Marco Elver <> |
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Thus far, accesses marked with data_race() would still require the racing access to be marked in some way (be it with READ_ONCE(), WRITE_ONCE(), or data_race() itself), as otherwise KCSAN would still report a data race. This requirement, however, seems to be unintuitive, and some valid use-cases demand *not* marking other accesses, as it might hide more serious bugs (e.g. diagnostic reads).
Therefore, this commit changes data_race() to no longer require marking racing accesses (although it's still recommended if possible).
The alternative would have been introducing another variant of data_race(), however, since usage of data_race() already needs to be carefully reasoned about, distinguishing between these cases likely adds more complexity in the wrong place.
Link: https://lkml.kernel.org/r/20200331131002.GA30975@willie-the-truck Signed-off-by: Marco Elver <elver@google.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Will Deacon <will@kernel.org> Cc: Qian Cai <cai@lca.pw> --- include/linux/compiler.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/include/linux/compiler.h b/include/linux/compiler.h index f504edebd5d7..1729bd17e9b7 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -326,9 +326,9 @@ unsigned long read_word_at_a_time(const void *addr) #define data_race(expr) \ ({ \ typeof(({ expr; })) __val; \ - kcsan_nestable_atomic_begin(); \ + kcsan_disable_current(); \ __val = ({ expr; }); \ - kcsan_nestable_atomic_end(); \ + kcsan_enable_current(); \ __val; \ }) #else -- 2.26.0.rc2.310.g2932bb562d-goog
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