On Mon, Jun 25, 2018 at 1:59 PM, Mark Rutland <mark.rutl...@arm.com> wrote: > From: Peter Zijlstra <pet...@infradead.org> > > Mark found ldsem_cmpxchg() needed an (atomic_long_t *) cast to keep > working after making the atomic_long interface type safe. > > Needing casts is bad form, which made me look at the code. There are no > ld_semaphore::count users outside of these functions so there is no > reason why it can not be an atomic_long_t in the first place, obviating > the need for this cast. > > That also ensures the loads use atomic_long_read(), which implies (at > least) READ_ONCE() in order to guarantee single-copy-atomic loads. > > When using atomic_long_try_cmpxchg() the ldsem_cmpxchg() wrapper gets > very thin (the only difference is not changing *old on success, which > most callers don't seem to care about). > > So rework the whole thing to use atomic_long_t and its accessors > directly. > > While there, fixup all the horrible comment styles.
> - ldsem_atomic_update(-LDSEM_WAIT_BIAS, sem); > + atomic_long_add_return(-LDSEM_WAIT_BIAS, &sem->count); I suppose it's simple atomic_long_add() here? Good fix! Reviewed-by: Andy Shevchenko <andy.shevche...@gmail.com> -- With Best Regards, Andy Shevchenko
