The following commit has been merged into the locking/kcsan branch of tip: Commit-ID: d071e91361bbfef524ae8abf7e560fb294d0ad64 Gitweb: https://git.kernel.org/tip/d071e91361bbfef524ae8abf7e560fb294d0ad64 Author: Marco Elver <elver@xxxxxxxxxx> AuthorDate: Tue, 31 Mar 2020 21:32:33 +02:00 Committer: Paul E. McKenney <paulmck@xxxxxxxxxx> CommitterDate: Mon, 13 Apr 2020 17:18:15 -07:00 kcsan: Change data_race() to no longer require marking racing accesses 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 Cc: Paul E. McKenney <paulmck@xxxxxxxxxx> Cc: Will Deacon <will@xxxxxxxxxx> Cc: Qian Cai <cai@xxxxxx> Acked-by: Will Deacon <will@xxxxxxxxxx> Signed-off-by: Marco Elver <elver@xxxxxxxxxx> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx> --- 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 f504ede..1729bd1 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
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