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Tsirkin" , Stefan Hajnoczi , Stefano Garzarella , Parav Pandit , Christoph Hellwig , Christian Brauner , Randy Dunlap , Matthew Wilcox , Al Viro , Jens Axboe , bcrl@kvack.org, Jonathan Corbet , =?UTF-8?Q?Mika_Penttil=c3=a4?= , Dan Carpenter , joro@8bytes.org, virtualization , netdev@vger.kernel.org, kvm , linux-fsdevel@vger.kernel.org, iommu@lists.linux-foundation.org, linux-kernel References: <20210517095513.850-1-xieyongji@bytedance.com> <20210517095513.850-12-xieyongji@bytedance.com> <3740c7eb-e457-07f3-5048-917c8606275d@redhat.com> From: Jason Wang Message-ID: <5a68bb7c-fd05-ce02-cd61-8a601055c604@redhat.com> Date: Thu, 27 May 2021 13:00:07 +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: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org 在 2021/5/27 下午12:57, Yongji Xie 写道: > On Thu, May 27, 2021 at 12:13 PM Jason Wang wrote: >> >> 在 2021/5/17 下午5:55, Xie Yongji 写道: >>> + >>> +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. >> > How about using wait_event_killable_timeout() instead? Probably, and then we need choose a suitable timeout and more important, need to report the failure to virtio. Thanks > > Thanks, > Yongji >