From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH 1/2] KVM: kvm-io: support cookies
Date: Wed, 03 Jul 2013 11:21:23 +0200
Message-ID: <51D3ED13.2020408@redhat.com>
References: <1372841780-29645-1-git-send-email-cornelia.huck@de.ibm.com> <1372841780-29645-2-git-send-email-cornelia.huck@de.ibm.com> <51D3E96E.5080405@redhat.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-15
Content-Transfer-Encoding: 7bit
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>,
	Gleb Natapov <gleb@redhat.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Heiko Carstens <heiko.carstens@de.ibm.com>,
	Martin Schwidefsky <schwidefsky@de.ibm.com>,
	KVM <kvm@vger.kernel.org>,
	linux-s390 <linux-s390@vger.kernel.org>
To: unlisted-recipients:; (no To-header on input)
Return-path: <kvm-owner@vger.kernel.org>
Received: from mail-qc0-f173.google.com ([209.85.216.173]:44499 "EHLO
	mail-qc0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1754628Ab3GCJVc (ORCPT <rfc822;kvm@vger.kernel.org>);
	Wed, 3 Jul 2013 05:21:32 -0400
In-Reply-To: <51D3E96E.5080405@redhat.com>
Sender: kvm-owner@vger.kernel.org
List-ID: <kvm.vger.kernel.org>

Il 03/07/2013 11:05, Paolo Bonzini ha scritto:
> Nice idea, though I don't really like the duplication between
> kvm_io_bus_write and kvm_io_bus_write_cookie.
> 
> Can you make kvm_io_bus_write, and perhaps kvm_io_bus_read too, return
> the cookie, and return -EINVAL here if the cookie is garbage?

On second though---no need to return -EINVAL, you can just pass the
cookie by value and tail-call kvm_io_bus_write.  Whatever makes the s390
code look nicer.

Paolo

> (Unfortunately, most callers of kvm_io_bus_read/write expect them to
> never return a value that is >= 0, but there aren't many so it's easily
> solved).