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Re: [Qemu-devel] [PATCH] block: Fix compiler warning (-Werror=uninitiali
From: |
Andreas Färber |
Subject: |
Re: [Qemu-devel] [PATCH] block: Fix compiler warning (-Werror=uninitialized) |
Date: |
Thu, 19 Sep 2013 18:59:23 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130801 Thunderbird/17.0.8 |
Am 17.09.2013 18:43, schrieb Stefan Weil:
> 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 <address@hidden>
> ---
> block/stream.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/block/stream.c b/block/stream.c
> index 078ce4a..fc19194 100644
> --- a/block/stream.c
> +++ b/block/stream.c
> @@ -108,7 +108,7 @@ static void coroutine_fn stream_run(void *opaque)
>
> for (sector_num = 0; sector_num < end; sector_num += n) {
> uint64_t delay_ns = 0;
> - bool copy;
> + bool copy = false;
>
> wait:
> /* Note that even when no rate limit is applied we need to yield
> @@ -123,7 +123,6 @@ wait:
> 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). */
Sorry for not spotting this patch earlier. This hunk looks wrong and
needs to be dropped, I believe. In the ret >= 0 && copy case, there is a
"goto wait" which would now no longer be able to go from copy == true ->
copy == false. Not sure if that can happen in practice.
Andreas
> @@ -138,7 +137,7 @@ 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) {
>
--
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