Re: [Qemu-devel] [Qemu-block] [PATCH 03/17] block: Switch BlockRequest to byte-based

From: Eric Blake <eblake@redhat.com>
To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: qemu-devel@nongnu.org, kwolf@redhat.com,
	Fam Zheng <famz@redhat.com>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	qemu-block@nongnu.org, Max Reitz <mreitz@redhat.com>
Subject: Re: [Qemu-devel] [Qemu-block] [PATCH 03/17] block: Switch BlockRequest to byte-based
Date: Thu, 14 Jul 2016 06:33:22 -0600	[thread overview]
Message-ID: <57878692.8020101@redhat.com> (raw)
In-Reply-To: <20160714121532.GF15476@stefanha-x1.localdomain>

[-- Attachment #1: Type: text/plain, Size: 1114 bytes --]

On 07/14/2016 06:15 AM, Stefan Hajnoczi wrote:
> On Wed, Jun 22, 2016 at 09:51:00AM -0600, Eric Blake wrote:
>> @@ -2204,14 +2203,15 @@ BlockAIOCB *bdrv_aio_discard(BlockDriverState *bs,
>>  {
>>      Coroutine *co;
>>      BlockAIOCBCoroutine *acb;
>> +    QEMUIOVector qiov = { .size = nb_sectors << BDRV_SECTOR_BITS, };
>>
>>      trace_bdrv_aio_discard(bs, sector_num, nb_sectors, opaque);
>>
>>      acb = qemu_aio_get(&bdrv_em_co_aiocb_info, bs, cb, opaque);
>>      acb->need_bh = true;
>>      acb->req.error = -EINPROGRESS;
>> -    acb->req.sector = sector_num;
>> -    acb->req.nb_sectors = nb_sectors;
>> +    acb->req.offset = sector_num << BDRV_SECTOR_BITS;
>> +    acb->req.qiov = &qiov;
> 
> This looks unsafe: the pointer to a stack-allocated qiov is held after
> the function returns.

Hmm, you're right.  I'll definitely have to rework this one.  But since
the ONLY thing being passed through the qiov was the size, it may be
easiest to just add acb->req.size.

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

[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 604 bytes --]