Re: [Qemu-devel] [PATCH 2/2] block: in commit, determine base image from the top image

[Eric Blake <eblake@redhat.com>]

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On 10/09/2012 11:56 PM, Jeff Cody wrote:
> This simplifies some code and error checking, and also fixes a bug.
> 
> bdrv_find_backing_image() should only be passed absolute filenames,
> or filenames relative to the chain.  In the QMP message handler for
> block commit, when looking up the base do so from the determined top
> image, so we know it is reachable from top.
> 
> Signed-off-by: Jeff Cody <jcody@redhat.com>
> ---

> +++ b/blockdev.c

> @@ -1182,6 +1172,17 @@ void qmp_block_commit(const char *device,
>          return;
>      }
>  
> +    if (base && has_base) {

Code motion, but won't this order trigger valgrind warnings about
jumping based on a read of uninitialized memory?  That is, the canonical
ordering is 'has_base && base' (although the end result is the same,
with the difference only observable in valgrind).

-- 
Eric Blake   eblake@redhat.com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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