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[109.67.41.16]) by smtp.gmail.com with ESMTPSA id f12sm21591802wmc.46.2020.08.10.06.37.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Aug 2020 06:37:03 -0700 (PDT) Date: Mon, 10 Aug 2020 09:37:00 -0400 From: "Michael S. Tsirkin" To: Jason Wang Cc: "Zhu, Lingshan" , alex.williamson@redhat.com, pbonzini@redhat.com, sean.j.christopherson@intel.com, wanpengli@tencent.com, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, kvm@vger.kernel.org, eli@mellanox.com, shahafs@mellanox.com, parav@mellanox.com Subject: Re: [PATCH V5 1/6] vhost: introduce vhost_vring_call Message-ID: <20200810093630-mutt-send-email-mst@kernel.org> References: <20200731065533.4144-1-lingshan.zhu@intel.com> <20200731065533.4144-2-lingshan.zhu@intel.com> <5e646141-ca8d-77a5-6f41-d30710d91e6d@redhat.com> <156b8d71-6870-c163-fdfa-35bf4701987d@redhat.com> <20200804052050-mutt-send-email-mst@kernel.org> <14fd2bf1-e9c1-a192-bd6c-f1ee5fd227f6@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <14fd2bf1-e9c1-a192-bd6c-f1ee5fd227f6@redhat.com> Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Wed, Aug 05, 2020 at 10:16:16AM +0800, Jason Wang wrote: > > On 2020/8/4 下午5:21, Michael S. Tsirkin wrote: > > > > > >   +struct vhost_vring_call { > > > > > > +    struct eventfd_ctx *ctx; > > > > > > +    struct irq_bypass_producer producer; > > > > > > +    spinlock_t ctx_lock; > > > > > It's not clear to me why we need ctx_lock here. > > > > > > > > > > Thanks > > > > Hi Jason, > > > > > > > > we use this lock to protect the eventfd_ctx and irq from race conditions, > > > We don't support irq notification from vDPA device driver in this version, > > > do we still have race condition? > > > > > > Thanks > > Jason I'm not sure what you are trying to say here. > > > I meant we change the API from V4 so driver won't notify us if irq is > changed. > > Then it looks to me there's no need for the ctx_lock, everyhing could be > synchronized with vq mutex. > > Thanks Jason do you want to post a cleanup patch simplifying code along these lines? Thanks, > > > >