mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-10-30 08:02:30 +00:00
068df05363
Previous to the change to distinguish read-write accesses, when CONFIG_KCSAN_ASSUME_PLAIN_WRITES_ATOMIC=y is set, KCSAN would consider the non-atomic bitops as atomic. We want to partially revert to this behaviour, but with one important distinction: report racing modifications, since lost bits due to non-atomicity are certainly possible. Given the operations here only modify a single bit, assuming non-atomicity of the writer is sufficient may be reasonable for certain usage (and follows the permissible nature of the "assume plain writes atomic" rule). In other words: 1. We want non-atomic read-modify-write races to be reported; this is accomplished by kcsan_check_read(), where any concurrent write (atomic or not) will generate a report. 2. We do not want to report races with marked readers, but -do- want to report races with unmarked readers; this is accomplished by the instrument_write() ("assume atomic write" with Kconfig option set). With the above rules, when KCSAN_ASSUME_PLAIN_WRITES_ATOMIC is selected, it is hoped that KCSAN's reporting behaviour is better aligned with current expected permissible usage for non-atomic bitops. Note that, a side-effect of not telling KCSAN that the accesses are read-writes, is that this information is not displayed in the access summary in the report. It is, however, visible in inline-expanded stack traces. For now, it does not make sense to introduce yet another special case to KCSAN's runtime, only to cater to the case here. Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Will Deacon <will@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Daniel Axtens <dja@axtens.net> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: <linux-arch@vger.kernel.org> Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> |
||
---|---|---|
.. | ||
__ffs.h | ||
__fls.h | ||
arch_hweight.h | ||
atomic.h | ||
builtin-__ffs.h | ||
builtin-__fls.h | ||
builtin-ffs.h | ||
builtin-fls.h | ||
const_hweight.h | ||
ext2-atomic-setbit.h | ||
ext2-atomic.h | ||
ffs.h | ||
ffz.h | ||
find.h | ||
fls.h | ||
fls64.h | ||
hweight.h | ||
instrumented-atomic.h | ||
instrumented-lock.h | ||
instrumented-non-atomic.h | ||
le.h | ||
lock.h | ||
non-atomic.h | ||
sched.h |