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Date: Thu, 4 Feb 2016 13:24:33 +0100
From: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20160204122433.GA2314@noname>
References: <1454581157-9858-1-git-send-email-xiecl.fnst@cn.fujitsu.com>
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In-Reply-To: <1454581157-9858-1-git-send-email-xiecl.fnst@cn.fujitsu.com>
Subject: Re: [Qemu-devel] [PATCH] quorum: fix segfault when read fails in
	fifo mode
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To: Changlong Xie <xiecl.fnst@cn.fujitsu.com>
Cc: Alberto Garcia <berto@igalia.com>, qemu devel <qemu-devel@nongnu.org>, "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Am 04.02.2016 um 11:19 hat Changlong Xie geschrieben:
> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
> Signed-off-by: Changlong Xie <xiecl.fnst@cn.fujitsu.com>
> ---
>  block/quorum.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/block/quorum.c b/block/quorum.c
> index a5ae4b8..0965277 100644
> --- a/block/quorum.c
> +++ b/block/quorum.c
> @@ -295,6 +295,9 @@ static void quorum_aio_cb(void *opaque, int ret)
>              quorum_copy_qiov(acb->qiov, &acb->qcrs[acb->child_iter].qiov);
>          }
>          acb->vote_ret = ret;
> +        if (ret < 0) {
> +            acb->child_iter--;
> +        }
>          quorum_aio_finalize(acb);
>          return;
>      }

This looks semantically correct to me (but I'd like to have an Ack from
Berto), but I would fix it above: We shouldn't do ++acb->child_iter in
the first place if the new value is >= s->num_children. So instead of
decrementing after the fact, just move the increment to inside the then
branch above.

Kevin