The virtio event_index feature lets the device driver tell the device
how many requests to process before raising the next interrupt.
virtio-blk-test.c tries to verify that the device does not raise an
interrupt unnecessarily.
Unfortunately the test has a race condition. It spins checking for an
interrupt up to 100 times and then assumes the request has finished. On
a slow host the I/O request could still be in flight and the test would
fail.
This patch waits for the request to complete, or until a 30-second
timeout is reached. If an interrupt is raised while waiting the test
fails since the device was not supposed to raise interrupts.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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