Re: [PATCH v2 2/3] virito_pci: add timeout to reset device operation

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在 2021/4/8 下午5:44, Max Gurtovoy 写道:

On 4/8/2021 12:01 PM, Jason Wang wrote:

在 2021/4/8 下午4:11, Max Gurtovoy 写道:
According to the spec after writing 0 to device_status, the driver MUST
wait for a read of device_status to return 0 before reinitializing the
device. In case we have a device that won't return 0, the reset
operation will loop forever and cause the host/vm to stuck. Set timeout
for 3 minutes before giving up on the device.

Signed-off-by: Max Gurtovoy <mgurtovoy@xxxxxxxxxx>
---
  drivers/virtio/virtio_pci_modern.c | 10 +++++++++-
  1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
index cc3412a96a17..dcee616e8d21 100644
--- a/drivers/virtio/virtio_pci_modern.c
+++ b/drivers/virtio/virtio_pci_modern.c
@@ -162,6 +162,7 @@ static int vp_reset(struct virtio_device *vdev)
  {
      struct virtio_pci_device *vp_dev = to_vp_device(vdev);
      struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
+    unsigned long timeout = jiffies + msecs_to_jiffies(180000);
        /* 0 status means a reset. */
      vp_modern_set_status(mdev, 0);
@@ -169,9 +170,16 @@ static int vp_reset(struct virtio_device *vdev)
       * device_status to return 0 before reinitializing the device.
       * This will flush out the status write, and flush in device writes,
       * including MSI-X interrupts, if any.
+     * Set a timeout before giving up on the device.
       */
-    while (vp_modern_get_status(mdev))
+    while (vp_modern_get_status(mdev)) {
+        if (time_after(jiffies, timeout)) {


What happens if the device finish the rest after the timeout?


The driver will set VIRTIO_CONFIG_S_FAILED and one can re-probe it later on (e.g by re-scanning the pci bus).


Ok, so do we need the flush through vp_synchronize_vectors() here?

Thanks





Thanks


+            dev_err(&vdev->dev, "virtio: device not ready. "
+                "Aborting. Try again later\n");
+            return -EAGAIN;
+        }
          msleep(1);
+    }
      /* Flush pending VQ/configuration callbacks. */
      vp_synchronize_vectors(vdev);
      return 0;






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