devices: Make sure to drain virtio TX port on stop#583
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LGTM, thanks! @mtjhrc PTAAL. |
I've encountered a race-condition where guest writes data to stderr shortly before exiting and that data never manifests on the host. The reason seems to be in libkrun's pop_head_blocking() (in the virtio console TX thread), when the stop flag is set the thread returns None without checking the queue one final time. Data already sitting in the virtio transmit queue is abandoned. Reorder the thread::park() call to make sure we check the queue one last time before stopping, which will ensure flushing of any remaining data on the port. I've verified the fix with several thousand iterations of a test case that earlier reproduced the problem in typically 10-50. Signed-off-by: Daniel Müller <deso@posteo.net>
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Sorry, I rebased somehow thinking there was a need to update. |
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I've encountered a race-condition where guest writes data to stderr shortly before exiting and that data never manifests on the host. The reason seems to be in
pop_head_blocking()(in the virtio console TX thread), when thestopflag is set the thread returnsNonewithout checking the queue one final time. Data already sitting in the virtio transmit queue is abandoned.Reorder the
thread::park()call to make sure we check the queue one last time before stopping, which will ensure flushing of any remaining data on the port. I've verified the fix with several thousand iterations of a test case that earlier reproduced the problem in typically 10-50.