From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751920AbeFENKo (ORCPT ); Tue, 5 Jun 2018 09:10:44 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:54738 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751732AbeFENKm (ORCPT ); Tue, 5 Jun 2018 09:10:42 -0400 Reply-To: pmorel@linux.ibm.com Subject: Re: [PATCH v2 06/10] vfio: ccw: Make FSM functions atomic To: Cornelia Huck , 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 References: <1527243678-3140-1-git-send-email-pmorel@linux.vnet.ibm.com> <1527243678-3140-7-git-send-email-pmorel@linux.vnet.ibm.com> <20180605133850.3509a3d3.cohuck@redhat.com> From: Pierre Morel Date: Tue, 5 Jun 2018 15:10:11 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: <20180605133850.3509a3d3.cohuck@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-TM-AS-GCONF: 00 x-cbid: 18060513-0008-0000-0000-000002445EFE X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18060513-0009-0000-0000-000021AA644D Message-Id: <46613ac7-3156-7a78-7d49-acbc3f615b76@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-06-05_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1805220000 definitions=main-1806050151 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/06/2018 13:38, Cornelia Huck wrote: > On Fri, 25 May 2018 12:21:14 +0200 > Pierre Morel wrote: > >> We use mutex around the FSM function call to make the FSM >> event handling and state change atomic. > I'm still not really clear as to what this mutex is supposed to > serialize: > > - Modification of the state? > - Any calls in the state machine? > - A combination? (That would imply that we only deal with the state in > the state machine.) yes to all > >> Signed-off-by: Pierre Morel >> --- >> drivers/s390/cio/vfio_ccw_drv.c | 3 +-- >> drivers/s390/cio/vfio_ccw_private.h | 3 +++ >> 2 files changed, 4 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c >> index 6b7112e..98951d5 100644 >> --- a/drivers/s390/cio/vfio_ccw_drv.c >> +++ b/drivers/s390/cio/vfio_ccw_drv.c >> @@ -73,8 +73,6 @@ static void vfio_ccw_sch_io_todo(struct work_struct *work) >> >> private = container_of(work, struct vfio_ccw_private, io_work); >> vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_INTERRUPT); >> - if (private->mdev) >> - private->state = VFIO_CCW_STATE_IDLE; > Looks like an unrelated change? If you want to do all state changes > under the mutex, that should rather be moved than deleted, shouldn't it? It is moved to fsm_irq() which is called under mutex. fsm_irq() returns VFIO_CCW_STATE_IDLE. > >> } >> >> static void vfio_ccw_sch_event_todo(struct work_struct *work) -- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany