Re: [Qemu-block] [PATCH 05/21] hbitmap: improve dirty iter

[Stefan Hajnoczi]

On Fri, Dec 23, 2016 at 05:28:48PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> Make dirty iter resistant to resetting bits in corresponding HBitmap.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
> ---
>  include/qemu/hbitmap.h | 24 ++----------------------
>  util/hbitmap.c         | 23 ++++++++++++++++++++++-
>  2 files changed, 24 insertions(+), 23 deletions(-)
> 
> diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h
> index eb46475..2873a46 100644
> --- a/include/qemu/hbitmap.h
> +++ b/include/qemu/hbitmap.h
> @@ -243,10 +243,7 @@ void hbitmap_free(HBitmap *hb);
>   * the lowest-numbered bit that is set in @hb, starting at @first.
>   *
>   * Concurrent setting of bits is acceptable, and will at worst cause the
> - * iteration to miss some of those bits.  Resetting bits before the current
> - * position of the iterator is also okay.  However, concurrent resetting of
> - * bits can lead to unexpected behavior if the iterator has not yet reached
> - * those bits.
> + * iteration to miss some of those bits.  Resetting bits is also okay.
>   */
>  void hbitmap_iter_init(HBitmapIter *hbi, const HBitmap *hb, uint64_t first);

Do you need to modify hbitmap_iter_next_word() as well?  Otherwise it
uses the hbi->cur[] cached information and does not handle clearing bits
ahead of the iterator.

Stefan

signature.asc
Description: PGP signature