Re: [Qemu-devel] [PATCH 2/3] migration/postcopy: break the loop when there is no more page to discard

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Wei Yang (richardw.yang@linux.intel.com) wrote:
> When one is equal or bigger then end, it means there is no page to
> discard. Just break the loop in this case instead of processing it.
> 
> No functional change, just refactor it a little.
> 
> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> ---
>  migration/ram.c | 26 +++++++++++++-------------
>  1 file changed, 13 insertions(+), 13 deletions(-)
> 
> diff --git a/migration/ram.c b/migration/ram.c
> index b78169e811..b41b58ee54 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -2776,23 +2776,23 @@ static int postcopy_send_discard_bm_ram(MigrationState *ms,
>  
>      for (current = 0; current < end; ) {
>          unsigned long one = find_next_bit(unsentmap, end, current);
> +        unsigned long zero, discard_length;
>  
> -        if (one < end) {
> -            unsigned long zero = find_next_zero_bit(unsentmap, end, one + 1);
> -            unsigned long discard_length;
> +        if (one >= end) {
> +            break;
> +        }
>  
> -            if (zero >= end) {
> -                discard_length = end - one;
> -            } else {
> -                discard_length = zero - one;
> -            }
> -            if (discard_length) {
> -                postcopy_discard_send_range(ms, pds, one, discard_length);
> -            }
> -            current = one + discard_length;
> +        zero = find_next_zero_bit(unsentmap, end, one + 1);
> +
> +        if (zero >= end) {
> +            discard_length = end - one;
>          } else {
> -            current = one;
> +            discard_length = zero - one;
> +        }
> +        if (discard_length) {
> +            postcopy_discard_send_range(ms, pds, one, discard_length);
>          }
> +        current = one + discard_length;
>      }
>  
>      return 0;
> -- 
> 2.19.1
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK