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.
Other than that:
Reviewed-by: Davidlohr Bueso <davidl...@hp.com>
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