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Commit b26ba22b authored by Christian Borntraeger's avatar Christian Borntraeger Committed by Marcelo Tosatti
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KVM: s390: Gracefully handle busy conditions on ccw_device_start 



In rare cases a virtio command might try to issue a ccw before a former
ccw was answered with a tsch. This will cause CC=2 (busy). Lets just
retry in that case.

Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent 73fa21ea

drivers/s390/kvm/virtio_ccw.c

+8 −5
Original line number Diff line number Diff line
@@ -132,11 +132,14 @@ static int ccw_io_helper(struct virtio_ccw_device *vcdev, 
	unsigned long flags;

	int flag = intparm & VIRTIO_CCW_INTPARM_MASK;



	do {

		spin_lock_irqsave(get_ccwdev_lock(vcdev->cdev), flags);

		ret = ccw_device_start(vcdev->cdev, ccw, intparm, 0, 0);

		if (!ret)

			vcdev->curr_io |= flag;

		spin_unlock_irqrestore(get_ccwdev_lock(vcdev->cdev), flags);

		cpu_relax();

	} while (ret == -EBUSY);

	wait_event(vcdev->wait_q, doing_io(vcdev, flag) == 0);

	return ret ? ret : vcdev->err;

}