On Fri, Apr 20, 2018 at 03:21:30PM +0800, Michael Chang wrote:
> Rounding up the bufio->block_size to meet power of 2 to facilitate next_buf
> calcuation in grub_bufio_read.
>
> Signed-off-by: Michael Chang <mch...@suse.com>
> ---
> grub-core/io/bufio.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/grub-core/io/bufio.c b/grub-core/io/bufio.c
> index 22438277d..4d66b65a3 100644
> --- a/grub-core/io/bufio.c
> +++ b/grub-core/io/bufio.c
> @@ -61,6 +61,14 @@ grub_bufio_open (grub_file_t io, int size)
> size = ((io->size > GRUB_BUFIO_MAX_SIZE) ? GRUB_BUFIO_MAX_SIZE :
> io->size);
>
> + /* round up size to power of 2 */
May I ask you to say why here?
> + if (size & (size - 1))
> + {
> + int round_up;
> + for (round_up = 1; round_up < size; round_up <<= 1);
> + size = round_up;
> + }
Please use this (stolen from linux/drivers/md/raid5.c):
while (size & (size - 1))
size = (size | (size - 1)) + 1;
Daniel
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