Messages in this thread | | | From | Marco Elver <> | Date | Thu, 21 May 2020 11:47:54 +0200 | Subject | Re: [PATCH -tip 08/10] READ_ONCE, WRITE_ONCE: Remove data_race() wrapping |
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On Fri, 15 May 2020 at 17:04, Marco Elver <elver@google.com> wrote: > > The volatile access no longer needs to be wrapped in data_race(), > because we require compilers that emit instrumentation distinguishing > volatile accesses. > > Signed-off-by: Marco Elver <elver@google.com> > --- > 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 17c98b215572..fce56402c082 100644 > --- a/include/linux/compiler.h > +++ b/include/linux/compiler.h > @@ -229,7 +229,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, > #define __READ_ONCE_SCALAR(x) \ > ({ \ > typeof(x) *__xp = &(x); \ > - __unqual_scalar_typeof(x) __x = data_race(__READ_ONCE(*__xp)); \ > + __unqual_scalar_typeof(x) __x = __READ_ONCE(*__xp); \ > kcsan_check_atomic_read(__xp, sizeof(*__xp)); \
Some self-review: We don't need kcsan_check_atomic anymore, and this should be removed.
I'll send v2 to address this (together with fix to data_race() removing nested statement expressions).
> smp_read_barrier_depends(); \ > (typeof(x))__x; \ > @@ -250,7 +250,7 @@ do { \ > do { \ > typeof(x) *__xp = &(x); \ > kcsan_check_atomic_write(__xp, sizeof(*__xp)); \
Same.
> - data_race(({ __WRITE_ONCE(*__xp, val); 0; })); \ > + __WRITE_ONCE(*__xp, val); \ > } while (0) > > #define WRITE_ONCE(x, val) \ > -- > 2.26.2.761.g0e0b3e54be-goog >
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