From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:48086)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <chenliang88@huawei.com>) id 1X2GmR-0000aY-Vj
	for qemu-devel@nongnu.org; Wed, 02 Jul 2014 05:24:50 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <chenliang88@huawei.com>) id 1X2GmL-0004id-RK
	for qemu-devel@nongnu.org; Wed, 02 Jul 2014 05:24:43 -0400
Received: from szxga02-in.huawei.com ([119.145.14.65]:7274)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <chenliang88@huawei.com>) id 1X2GmL-0004hu-4X
	for qemu-devel@nongnu.org; Wed, 02 Jul 2014 05:24:37 -0400
Message-ID: <53B3CFB8.5000800@huawei.com>
Date: Wed, 2 Jul 2014 17:24:08 +0800
From: ChenLiang <chenliang88@huawei.com>
MIME-Version: 1.0
References: <1404291017-7456-1-git-send-email-arei.gonglei@huawei.com>
	<53B3CB04.5040909@redhat.com>
In-Reply-To: <53B3CB04.5040909@redhat.com>
Content-Type: text/plain; charset="ISO-8859-15"
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [PATCH] ide: fix double free
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: kwolf@redhat.com, arei.gonglei@huawei.com, weidong.huang@huawei.com, qemu-devel@nongnu.org, stefanha@redhat.com

On 2014/7/2 17:04, Paolo Bonzini wrote:

> This is definitely a heavyweight solution, and in fact the bug should 
> not be there in the first place.  See dma_complete:
> 
> static void dma_complete(DMAAIOCB *dbs, int ret)
> {
>     trace_dma_complete(dbs, ret, dbs->common.cb);
> 
>     dma_bdrv_unmap(dbs);
>     if (dbs->common.cb) {
>         dbs->common.cb(dbs->common.opaque, ret);
>     }
>     qemu_iovec_destroy(&dbs->iov);
>     if (dbs->bh) {
>         qemu_bh_delete(dbs->bh);
>         dbs->bh = NULL;
>     }
>     if (!dbs->in_cancel) {
>         /* Requests may complete while dma_aio_cancel is in progress.  In
>          * this case, the AIOCB should not be released because it is still
>          * referenced by dma_aio_cancel.  */
>         qemu_aio_release(dbs);
>     }
> }
> 
> Perhaps something like this?
> 
> diff --git a/dma-helpers.c b/dma-helpers.c
> index 53cbe92..21b70d12 100644
> --- a/dma-helpers.c
> +++ b/dma-helpers.c
> @@ -181,15 +181,15 @@ static void dma_aio_cancel(BlockDriverAIOCB *acb)
>  
>      trace_dma_aio_cancel(dbs);
>  
> +    dbs->in_cancel = true;
>      if (dbs->acb) {
>          BlockDriverAIOCB *acb = dbs->acb;
>          dbs->acb = NULL;
> -        dbs->in_cancel = true;
>          bdrv_aio_cancel(acb);
> -        dbs->in_cancel = false;
>      }
>      dbs->common.cb = NULL;
>      dma_complete(dbs, 0);
> +    qemu_aio_release(dbs);
>  }
>  
>  static const AIOCBInfo dma_aiocb_info = {
> 
> 
> .
> 

acked, thanks

Best regards
Chenliang