On Thu, Feb 27, 2014 at 05:28:24AM +0000, Davidlohr Bueso wrote:
> On Fri, 2014-02-21 at 17:22 +0000, Will Deacon wrote:
> > The asm-generic rwsem implementation directly acceses sem->cnt when
> > performing a __down_read_trylock operation. Whilst this is probably safe
> > on all architectures, we should stick to the atomic_long_* API and use
> > atomic_long_read instead.
> >
> > Signed-off-by: Will Deacon <will.dea...@arm.com>
> > ---
> > include/asm-generic/rwsem.h | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/include/asm-generic/rwsem.h b/include/asm-generic/rwsem.h
> > index bb1e2cdeb9bf..75af612f54f8 100644
> > --- a/include/asm-generic/rwsem.h
> > +++ b/include/asm-generic/rwsem.h
> > @@ -41,7 +41,7 @@ static inline int __down_read_trylock(struct rw_semaphore
> > *sem)
> > {
> > long tmp;
> >
> > - while ((tmp = sem->count) >= 0) {
> > + while ((tmp = atomic_long_read((atomic_long_t *)&sem->count)) >= 0) {
>
> That's pretty ugly, how about having infinite look and just do the tmp
> assign separately from the conditional?
>
> It also looks like a cpu_relax() could help here between iterations.
Sure, I can do these in a separate patch (this patch is just a simple fix).
> Reviewed-by: Davidlohr Bueso <davidl...@hp.com>
Thanks,
Will
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