On Wed 02-04-14 23:19:06, Jianyu Zhan wrote:
> A bitwise flag comparison could be done using a more efficient bit-ops way.
OK, but have you checked the generated code is actually any better? This
is something I'd expect a compiler might be able to optimize anyway. And the
original code looks more readable to me.
Honza
> Signed-off-by: Jianyu Zhan <nasa4...@gmail.com>
> ---
> include/linux/blkdev.h | 13 +++----------
> 1 file changed, 3 insertions(+), 10 deletions(-)
>
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 1e1fa3f..adfa40a 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -655,16 +655,9 @@ static inline bool rq_mergeable(struct request *rq)
> static inline bool blk_check_merge_flags(unsigned int flags1,
> unsigned int flags2)
> {
> - if ((flags1 & REQ_DISCARD) != (flags2 & REQ_DISCARD))
> - return false;
> -
> - if ((flags1 & REQ_SECURE) != (flags2 & REQ_SECURE))
> - return false;
> -
> - if ((flags1 & REQ_WRITE_SAME) != (flags2 & REQ_WRITE_SAME))
> - return false;
> -
> - return true;
> + return (flags1 & (REQ_DISCARD | REQ_SECURE | REQ_WRITE_SAME)) ^
> + (flags2 & (REQ_DISCARD | REQ_SECURE | REQ_WRITE_SAME))
> + == 0;
> }
>
> static inline bool blk_write_same_mergeable(struct bio *a, struct bio *b)
> --
> 1.9.0.GIT
>
--
Jan Kara <j...@suse.cz>
SUSE Labs, CR
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
