Commit ef688e15 authored Jun 12, 2009 by Rusty Russell

virtio: meet virtio spec by finalizing features before using device

Virtio devices are supposed to negotiate features before they start using
the device, but the current code doesn't do this. This is because the
driver's probe() function invariably has to add buffers to a virtqueue,
or probe the disk (virtio_blk).

This currently doesn't matter since no existing backend is strict about
the feature negotiation. But it's possible to imagine a future feature
which completely changes how a device operates: in this case, we'd need
to acknowledge it before using the device.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

parent 20f77f56

drivers/virtio/virtio.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -118,13 +118,14 @@ static int virtio_dev_probe(struct device *_d)
		if (device_features & (1 << i))
		set_bit(i, dev->features);

		dev->config->finalize_features(dev);

		err = drv->probe(dev);
		if (err)
		add_status(dev, VIRTIO_CONFIG_S_FAILED);
		else {
		dev->config->finalize_features(dev);
		else
		add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
		}

		return err;
		}

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