From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933057AbeDXIlK (ORCPT ); Tue, 24 Apr 2018 04:41:10 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:44584 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932850AbeDXIlD (ORCPT ); Tue, 24 Apr 2018 04:41:03 -0400 Subject: Re: [PATCH 01/10] vfio: ccw: Moving state change out of IRQ context To: Dong Jia Shi Cc: pasic@linux.vnet.ibm.com, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, cohuck@redhat.com References: <1524149293-12658-1-git-send-email-pmorel@linux.vnet.ibm.com> <1524149293-12658-2-git-send-email-pmorel@linux.vnet.ibm.com> <20180424065442.GV12194@bjsdjshi@linux.vnet.ibm.com> From: Pierre Morel Date: Tue, 24 Apr 2018 10:40:56 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <20180424065442.GV12194@bjsdjshi@linux.vnet.ibm.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: 18042408-0012-0000-0000-000005CE1CE0 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18042408-0013-0000-0000-0000194A8B57 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-04-24_02:,, 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 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1804240086 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 24/04/2018 08:54, Dong Jia Shi wrote: > * Pierre Morel [2018-04-19 16:48:04 +0200]: > > [...] > >> @@ -94,9 +83,15 @@ static void vfio_ccw_sch_io_todo(struct work_struct *work) >> static void vfio_ccw_sch_irq(struct subchannel *sch) >> { >> struct vfio_ccw_private *private = dev_get_drvdata(&sch->dev); >> + struct irb *irb = this_cpu_ptr(&cio_irb); >> >> inc_irq_stat(IRQIO_CIO); >> - vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_INTERRUPT); >> + memcpy(&private->irb, irb, sizeof(*irb)); >> + >> + WARN_ON(work_pending(&private->io_work)); > Hmm, why do we need this? The current design insure that we have not two concurrent SSCH requests. How ever I want here to track spurious interrupt. If we implement cancel, halt or clear requests, we also may trigger (AFAIU) a second interrupts depending on races between instructions, controller and device. We do not need it strongly. > >> + queue_work(vfio_ccw_work_q, &private->io_work); >> + if (private->completion) >> + complete(private->completion); >> } >> >> static int vfio_ccw_sch_probe(struct subchannel *sch) > [...] > -- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany