Re: [Qemu-devel] [PATCH v2] block: Fix compiler warning (-Werror=uninitialized)

[Stefan Hajnoczi <stefanha@gmail.com>]

On Sun, Sep 22, 2013 at 08:19:10AM +0200, Stefan Weil wrote:
> The patch fixes a warning from gcc (Debian 4.6.3-14+rpi1) 4.6.3:
> 
> block/stream.c:141:22: error:
> ‘copy’ may be used uninitialized in this function [-Werror=uninitialized]
> 
> This is not a real bug - a better compiler would not complain.
> 
> Now 'copy' has always a defined value, so the check for ret >= 0
> can be removed.
> 
> Signed-off-by: Stefan Weil <sw@weilnetz.de>
> ---
> 
> v2:
> 
> As noted by Andreas Färber, 'copy' must be set to false after the goto label.
> Thanks for this hint.
> 
> Regards,
> Stefan
> 
>  block/stream.c |    5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/block/stream.c b/block/stream.c
> index 078ce4a..45837f4 100644
> --- a/block/stream.c
> +++ b/block/stream.c
> @@ -119,11 +119,12 @@ wait:
>              break;
>          }
>  
> +        copy = false;
> +
>          ret = bdrv_is_allocated(bs, sector_num,
>                                  STREAM_BUFFER_SIZE / BDRV_SECTOR_SIZE, &n);
>          if (ret == 1) {
>              /* Allocated in the top, no need to copy.  */
> -            copy = false;
>          } else if (ret >= 0) {
>              /* Copy if allocated in the intermediate images.  Limit to the
>               * known-unallocated area [sector_num, sector_num+n).  */
> @@ -138,7 +139,7 @@ wait:
>              copy = (ret == 1);
>          }
>          trace_stream_one_iteration(s, sector_num, n, ret);
> -        if (ret >= 0 && copy) {
> +        if (copy) {
>              if (s->common.speed) {
>                  delay_ns = ratelimit_calculate_delay(&s->limit, n);
>                  if (delay_ns > 0) {
> -- 
> 1.7.10.4

Acked-by: Stefan Hajnoczi <stefanha@redhat.com>