From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:53222)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <pbonzini@redhat.com>) id 1XsqEo-0002uo-FQ
	for qemu-devel@nongnu.org; Mon, 24 Nov 2014 04:47:24 -0500
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <pbonzini@redhat.com>) id 1XsqEh-0001By-RH
	for qemu-devel@nongnu.org; Mon, 24 Nov 2014 04:47:18 -0500
Received: from mx1.redhat.com ([209.132.183.28]:39998)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <pbonzini@redhat.com>) id 1XsqEh-0001Bj-JK
	for qemu-devel@nongnu.org; Mon, 24 Nov 2014 04:47:11 -0500
Message-ID: <5472FE95.1090503@redhat.com>
Date: Mon, 24 Nov 2014 10:47:01 +0100
From: Paolo Bonzini <pbonzini@redhat.com>
MIME-Version: 1.0
References: <1415286601-30715-1-git-send-email-ming.lei@canonical.com>	<1415286601-30715-2-git-send-email-ming.lei@canonical.com>	<546B5551.6030208@redhat.com>
	<CACVXFVMZLNQCLWp4pcG18OpNzuf6PS691uVtcbRuuy8=LA3Tyg@mail.gmail.com>
In-Reply-To: <CACVXFVMZLNQCLWp4pcG18OpNzuf6PS691uVtcbRuuy8=LA3Tyg@mail.gmail.com>
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [PATCH v3 1/3] linux-aio: fix submit aio as a batch
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: Ming Lei <ming.lei@canonical.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Peter Maydell <peter.maydell@linaro.org>, =?UTF-8?B?QmVub8OudCBDYW5ldA==?= <benoit.canet@irqsave.net>, qemu-devel <qemu-devel@nongnu.org>, Stefan Hajnoczi <stefanha@redhat.com>



On 22/11/2014 13:16, Ming Lei wrote:
> > > +static int ioq_enqueue(struct qemu_laio_state *s, struct iocb *iocb)
> > >  {
> > >      unsigned int idx = s->io_q.idx;
> > >
> > > +    if (unlikely(idx == s->io_q.size)) {
> > > +        return -1;
> >
> > return -EAGAIN?
>
> It means the io queue is full, so the code has to fail the current
> request.

Right, but "-1" is "-EPERM" which doesn't make much sense.  I think the
right thing to do is to return EAGAIN, and let the owner figure it out.
 For example, a SCSI device might return a "BUSY" status code.

Paolo