From: Greg KH <gregkh@linuxfoundation.org>
To: Jason Wang <jasowang@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
Xie Yongji <xieyongji@bytedance.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, zhe.he@windriver.com,
xiaodong.liu@intel.com, songmuchun@bytedance.com,
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
Subject: Re: [PATCH v9 16/17] vduse: Introduce VDUSE - vDPA Device in Userspace
Date: Wed, 14 Jul 2021 08:47:36 +0200 [thread overview]
Message-ID: <YO6IiDIMUjQsA2LS@kroah.com> (raw)
In-Reply-To: <0565ed6c-88e2-6d93-7cc6-7b4afaab599c@redhat.com>
On Wed, Jul 14, 2021 at 02:02:50PM +0800, Jason Wang wrote:
>
> 在 2021/7/14 下午1:54, Michael S. Tsirkin 写道:
> > On Wed, Jul 14, 2021 at 01:45:39PM +0800, Jason Wang wrote:
> > > > +static int vduse_dev_msg_sync(struct vduse_dev *dev,
> > > > + struct vduse_dev_msg *msg)
> > > > +{
> > > > + int ret;
> > > > +
> > > > + init_waitqueue_head(&msg->waitq);
> > > > + spin_lock(&dev->msg_lock);
> > > > + msg->req.request_id = dev->msg_unique++;
> > > > + vduse_enqueue_msg(&dev->send_list, msg);
> > > > + wake_up(&dev->waitq);
> > > > + spin_unlock(&dev->msg_lock);
> > > > +
> > > > + wait_event_killable_timeout(msg->waitq, msg->completed,
> > > > + VDUSE_REQUEST_TIMEOUT * HZ);
> > > > + spin_lock(&dev->msg_lock);
> > > > + if (!msg->completed) {
> > > > + list_del(&msg->list);
> > > > + msg->resp.result = VDUSE_REQ_RESULT_FAILED;
> > > > + }
> > > > + ret = (msg->resp.result == VDUSE_REQ_RESULT_OK) ? 0 : -EIO;
> > >
> > > I think we should mark the device as malfunction when there is a timeout and
> > > forbid any userspace operations except for the destroy aftwards for safety.
> > This looks like if one tried to run gdb on the program the behaviour
> > will change completely because kernel wants it to respond within
> > specific time. Looks like a receipe for heisenbugs.
> >
> > Let's not build interfaces with arbitrary timeouts like that.
> > Interruptible wait exists for this very reason.
>
>
> The problem is. Do we want userspace program like modprobe to be stuck for
> indefinite time and expect the administrator to kill that?
Why would modprobe be stuck for forever?
Is this on the module probe path?
next prev parent reply other threads:[~2021-07-14 6:47 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-13 8:46 [PATCH v9 00/17] Introduce VDUSE - vDPA Device in Userspace Xie Yongji
2021-07-13 8:46 ` [PATCH v9 01/17] iova: Export alloc_iova_fast() and free_iova_fast() Xie Yongji
2021-07-13 8:46 ` [PATCH v9 02/17] file: Export receive_fd() to modules Xie Yongji
2021-07-13 8:46 ` [PATCH v9 03/17] vdpa: Fix code indentation Xie Yongji
2021-07-14 4:20 ` Joe Perches
2021-07-14 5:48 ` Yongji Xie
2021-07-13 8:46 ` [PATCH v9 04/17] vdpa: Fail the vdpa_reset() if fail to set device status to zero Xie Yongji
2021-07-13 8:46 ` [PATCH v9 05/17] vhost-vdpa: Fail the vhost_vdpa_set_status() on reset failure Xie Yongji
2021-07-13 8:46 ` [PATCH v9 06/17] vhost-vdpa: Handle the failure of vdpa_reset() Xie Yongji
2021-07-13 8:46 ` [PATCH v9 07/17] virtio: Don't set FAILED status bit on device index allocation failure Xie Yongji
2021-07-13 11:02 ` Dan Carpenter
2021-07-13 11:25 ` Yongji Xie
2021-07-13 8:46 ` [PATCH v9 08/17] virtio_config: Add a return value to reset function Xie Yongji
2021-07-13 8:46 ` [PATCH v9 09/17] virtio-vdpa: Handle the failure of vdpa_reset() Xie Yongji
2021-07-13 8:46 ` [PATCH v9 10/17] virtio: Handle device reset failure in register_virtio_device() Xie Yongji
2021-07-13 8:46 ` [PATCH v9 11/17] vhost-iotlb: Add an opaque pointer for vhost IOTLB Xie Yongji
2021-07-13 8:46 ` [PATCH v9 12/17] vdpa: Add an opaque pointer for vdpa_config_ops.dma_map() Xie Yongji
2021-07-13 8:46 ` [PATCH v9 13/17] vdpa: factor out vhost_vdpa_pa_map() and vhost_vdpa_pa_unmap() Xie Yongji
2021-07-13 11:31 ` Dan Carpenter
2021-07-14 2:14 ` Jason Wang
2021-07-14 8:05 ` Dan Carpenter
2021-07-14 9:41 ` Jason Wang
2021-07-14 9:57 ` Dan Carpenter
2021-07-15 2:20 ` Jason Wang
2021-07-14 5:24 ` Yongji Xie
2021-07-13 8:46 ` [PATCH v9 14/17] vdpa: Support transferring virtual addressing during DMA mapping Xie Yongji
2021-07-13 8:46 ` [PATCH v9 15/17] vduse: Implement an MMU-based IOMMU driver Xie Yongji
2021-07-13 8:46 ` [PATCH v9 16/17] vduse: Introduce VDUSE - vDPA Device in Userspace Xie Yongji
2021-07-13 13:27 ` Dan Carpenter
2021-07-14 2:54 ` Jason Wang
2021-07-14 5:45 ` Yongji Xie
2021-07-14 5:45 ` Jason Wang
2021-07-14 5:54 ` Michael S. Tsirkin
2021-07-14 6:02 ` Jason Wang
2021-07-14 6:47 ` Greg KH [this message]
2021-07-14 8:56 ` Jason Wang
2021-07-14 6:49 ` Yongji Xie
2021-07-14 9:12 ` Jason Wang
2021-07-15 4:03 ` Yongji Xie
2021-07-15 5:00 ` Jason Wang
2021-07-13 8:46 ` [PATCH v9 17/17] Documentation: Add documentation for VDUSE Xie Yongji
2021-07-15 5:18 ` Jason Wang
2021-07-15 7:27 ` Yongji Xie
2021-12-15 10:10 ` [PATCH v9 00/17] Introduce VDUSE - vDPA Device in Userspace Liuxiangdong
2021-12-16 3:14 ` Yongji Xie
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