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Wed, 26 May 2021 21:13:07 -0700 (PDT) Received: from wangxiaodeMacBook-Air.local ([209.132.188.80]) by smtp.gmail.com with ESMTPSA id c134sm622801pfb.135.2021.05.26.21.13.00 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 26 May 2021 21:13:06 -0700 (PDT) Subject: Re: [PATCH v7 11/12] vduse: Introduce VDUSE - vDPA Device in Userspace To: Xie Yongji , mst@redhat.com, stefanha@redhat.com, sgarzare@redhat.com, parav@nvidia.com, hch@infradead.org, christian.brauner@canonical.com, rdunlap@infradead.org, willy@infradead.org, viro@zeniv.linux.org.uk, axboe@kernel.dk, bcrl@kvack.org, corbet@lwn.net, mika.penttila@nextfour.com, dan.carpenter@oracle.com, joro@8bytes.org Cc: virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, kvm@vger.kernel.org, linux-fsdevel@vger.kernel.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org References: <20210517095513.850-1-xieyongji@bytedance.com> <20210517095513.850-12-xieyongji@bytedance.com> From: Jason Wang Message-ID: <3740c7eb-e457-07f3-5048-917c8606275d@redhat.com> Date: Thu, 27 May 2021 12:12:58 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.10.2 MIME-Version: 1.0 In-Reply-To: <20210517095513.850-12-xieyongji@bytedance.com> Content-Type: text/plain; charset=gbk; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ÔÚ 2021/5/17 ÏÂÎç5:55, Xie Yongji дµÀ: > + > +static int vduse_dev_msg_sync(struct vduse_dev *dev, > + struct vduse_dev_msg *msg) > +{ > + init_waitqueue_head(&msg->waitq); > + spin_lock(&dev->msg_lock); > + vduse_enqueue_msg(&dev->send_list, msg); > + wake_up(&dev->waitq); > + spin_unlock(&dev->msg_lock); > + wait_event_killable(msg->waitq, msg->completed); What happens if the userspace(malicous) doesn't give a response forever? It looks like a DOS. If yes, we need to consider a way to fix that. Thanks > + spin_lock(&dev->msg_lock); > + if (!msg->completed) { > + list_del(&msg->list); > + msg->resp.result = VDUSE_REQUEST_FAILED; > + } > + spin_unlock(&dev->msg_lock); > + > + return (msg->resp.result == VDUSE_REQUEST_OK) ? 0 : -1; > +}