Re: [Qemu-stable] [Qemu-devel] [PATCH 02/12] migration: Don't lose errno across aio context changes

[John Snow]

On 04/12/2017 01:49 PM, Eric Blake wrote:
> set_drity_tracking() was assuming that the errno value set by

*cough*

> bdrv_create_dirty_bitmap() would not be corrupted by either
> blk_get_aio_context() or aio_context_release().  Rather than
> audit whether this assumption is safe, rewrite the code to just
> grab the value of errno sooner.
> 
> CC: address@hidden
> Signed-off-by: Eric Blake <address@hidden>
> ---
>  migration/block.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/migration/block.c b/migration/block.c
> index 18d50ff..9a9c214 100644
> --- a/migration/block.c
> +++ b/migration/block.c
> @@ -350,9 +350,9 @@ static int set_dirty_tracking(void)
>          aio_context_acquire(blk_get_aio_context(bmds->blk));
>          bmds->dirty_bitmap = bdrv_create_dirty_bitmap(blk_bs(bmds->blk),
>                                                        BLOCK_SIZE, NULL, 
> NULL);
> +        ret = -errno;
>          aio_context_release(blk_get_aio_context(bmds->blk));
>          if (!bmds->dirty_bitmap) {
> -            ret = -errno;
>              goto fail;
>          }
>      }
> 

Reviewed-by: John Snow <address@hidden>