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Commit 20887611 authored by Rusty Russell's avatar Rusty Russell
Browse files

lguest: notify on empty 



This is the lguest implementation of the VIRTIO_F_NOTIFY_ON_EMPTY feature.
It is currently only published for network devices, but it is turned on for
everyone.

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent b4f68be6

Documentation/lguest/lguest.c

+10 −2
Original line number Diff line number Diff line
@@ -157,6 +157,9 @@ struct virtqueue 


	/* The routine to call when the Guest pings us. */

	void (*handle_output)(int fd, struct virtqueue *me);



	/* Outstanding buffers */

	unsigned int inflight;

};



/* Remember the arguments to the program so we can "reboot" */
@@ -702,6 +705,7 @@ static unsigned get_vq_desc(struct virtqueue *vq, 
			errx(1, "Looped descriptor");

	} while ((i = next_desc(vq, i)) != vq->vring.num);



	vq->inflight++;

	return head;

}
@@ -719,6 +723,7 @@ static void add_used(struct virtqueue *vq, unsigned int head, int len) 
	/* Make sure buffer is written before we update index. */

	wmb();

	vq->vring.used->idx++;

	vq->inflight--;

}



/* This actually sends the interrupt for this virtqueue */
@@ -726,8 +731,9 @@ static void trigger_irq(int fd, struct virtqueue *vq) 
{

	unsigned long buf[] = { LHREQ_IRQ, vq->config.irq };



	/* If they don't want an interrupt, don't send one. */

	if (vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT)

	/* If they don't want an interrupt, don't send one, unless empty. */

	if ((vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT)

	    && vq->inflight)

		return;



	/* Send the Guest an interrupt tell them we used something up. */
@@ -1107,6 +1113,7 @@ static void add_virtqueue(struct device *dev, unsigned int num_descs, 
	vq->next = NULL;

	vq->last_avail_idx = 0;

	vq->dev = dev;

	vq->inflight = 0;



	/* Initialize the configuration. */

	vq->config.num = num_descs;
@@ -1368,6 +1375,7 @@ static void setup_tun_net(const char *arg) 


	/* Tell Guest what MAC address to use. */

	add_feature(dev, VIRTIO_NET_F_MAC);

	add_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY);

	set_config(dev, sizeof(conf), &conf);



	/* We don't need the socket any more; setup is done. */