From: Marco Elver Date: Tue, 31 Mar 2020 19:32:33 +0000 (+0200) Subject: kcsan: Change data_race() to no longer require marking racing accesses X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=d071e91361bbfef524ae8abf7e560fb294d0ad64;p=linux.git 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 Cc: Will Deacon Cc: Qian Cai Acked-by: Will Deacon Signed-off-by: Marco Elver Signed-off-by: Paul E. McKenney --- diff --git a/include/linux/compiler.h b/include/linux/compiler.h index f504edebd5d71..1729bd17e9b78 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