From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pierre Morel Subject: Re: [PATCH 01/10] vfio: ccw: Moving state change out of IRQ context Date: Tue, 24 Apr 2018 10:40:56 +0200 Message-ID: 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> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format="flowed" Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20180424065442.GV12194@bjsdjshi@linux.vnet.ibm.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Archive: List-Post: 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 List-ID: 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