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libqos: improve event_index test with timeout

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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>
This commit is contained in:
Stefan Hajnoczi 2014-09-29 16:40:11 +01:00 • committed by Peter Maydell
parent ed9114356b
commit e8c81b4d8a
3 changed files with 31 additions and 4 deletions
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22
tests/libqos/virtio.c
View file

@ -91,6 +91,28 @@ bool qvirtio_wait_queue_isr(const QVirtioBus *bus, QVirtioDevice *d,
return timeout != 0;
}
/* Wait for the status byte at given guest memory address to be set
*
* The virtqueue interrupt must not be raised, making this useful for testing
* event_index functionality.
*/
uint8_t qvirtio_wait_status_byte_no_isr(const QVirtioBus *bus,
QVirtioDevice *d,
QVirtQueue *vq,
uint64_t addr,
gint64 timeout_us)
{
gint64 start_time = g_get_monotonic_time();
uint8_t val;
while ((val = readb(addr)) == 0xff) {
clock_step(100);
g_assert(!bus->get_queue_isr_status(d, vq));
g_assert(g_get_monotonic_time() - start_time <= timeout_us);
}
return val;
}
bool qvirtio_wait_config_isr(const QVirtioBus *bus, QVirtioDevice *d,
uint64_t timeout)
{