On 06/06/2017 01:11 PM, Dmitry Vyukov wrote: > The comments are factored out from the code changes to make them > easier to read. Add them separately to explain some non-obvious > aspects. > > Signed-off-by: Dmitry Vyukov <[email protected]> > Cc: Mark Rutland <[email protected]> > Cc: Peter Zijlstra <[email protected]> > Cc: Will Deacon <[email protected]> > Cc: Andrew Morton <[email protected]> > Cc: Andrey Ryabinin <[email protected]> > Cc: Ingo Molnar <[email protected]> > Cc: [email protected] > Cc: [email protected] > Cc: [email protected] > Cc: [email protected] > --- > arch/x86/include/asm/atomic.h | 7 +++++++ > include/asm-generic/atomic-instrumented.h | 30 ++++++++++++++++++++++++++++++ > 2 files changed, 37 insertions(+) > > diff --git a/arch/x86/include/asm/atomic.h b/arch/x86/include/asm/atomic.h > index b7900346c77e..8a9e65e585db 100644 > --- a/arch/x86/include/asm/atomic.h > +++ b/arch/x86/include/asm/atomic.h > @@ -23,6 +23,13 @@ > */ > static __always_inline int arch_atomic_read(const atomic_t *v) > { > + /* > + * Note: READ_ONCE() here leads to double instrumentation as > + * both READ_ONCE() and atomic_read() contain instrumentation. > + * This is a deliberate choice. READ_ONCE_NOCHECK() is compiled to a > + * non-inlined function call that considerably increases binary size > + * and stack usage under KASAN. > + */
Not sure that this worth commenting. Whoever is looking into arch_atomic_read() internals probably don't even think about KASAN instrumentation, so I'd remove this comment. > return READ_ONCE((v)->counter); > } >
