From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754711AbeD3PrX (ORCPT ); Mon, 30 Apr 2018 11:47:23 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:39554 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753334AbeD3PrW (ORCPT ); Mon, 30 Apr 2018 11:47:22 -0400 Date: Mon, 30 Apr 2018 17:47:18 +0200 From: Cornelia Huck To: Pierre Morel Cc: pasic@linux.vnet.ibm.com, bjsdjshi@linux.vnet.ibm.com, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [PATCH 09/10] vfio: ccw: Suppressing the BOXED state Message-ID: <20180430174718.7b1e5651.cohuck@redhat.com> In-Reply-To: <32efd6b2-78b0-ae44-3a64-a092f9d412fe@linux.vnet.ibm.com> References: <1524149293-12658-1-git-send-email-pmorel@linux.vnet.ibm.com> <1524149293-12658-10-git-send-email-pmorel@linux.vnet.ibm.com> <20180425104429.582618f8.cohuck@redhat.com> <32efd6b2-78b0-ae44-3a64-a092f9d412fe@linux.vnet.ibm.com> Organization: Red Hat GmbH MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 25 Apr 2018 15:55:51 +0200 Pierre Morel wrote: > On 25/04/2018 10:44, Cornelia Huck wrote: > > On Thu, 19 Apr 2018 16:48:12 +0200 > > Pierre Morel wrote: > > > >> VFIO_CCW_STATE_BOXED and VFIO_CCW_STATE_BUSY are the same > >> states. > >> Let's only keep one: VFIO_CCW_STATE_BUSY > >> > >> Signed-off-by: Pierre Morel > >> --- > >> drivers/s390/cio/vfio_ccw_fsm.c | 9 --------- > >> drivers/s390/cio/vfio_ccw_private.h | 1 - > >> 2 files changed, 10 deletions(-) > > I think they were initially supposed to cover two different things: > > - BUSY: we're currently dealing with an I/O request > > - BOXED: the device currently won't talk to us or we won't talk to it > > > > It seems we never really did anything useful with BOXED; but should we? > > > I do not know what. The BUSY state is something we know that we'll get out of soon-ish (when the I/O request has finished). We could conceivably use a timeout and drop to the BOXED state if we don't get an answer. I think this plays also into the reserve/release and path handling questions. One of the more common reasons for devices to become boxed I've seen is another system doing a reserve on a dasd.