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Commit ebf9a5a9 authored by Rusty Russell's avatar Rusty Russell
Browse files

lguest: remove invalid interrupt forcing logic. 



20887611 (lguest: notify on empty) introduced
lguest support for the VIRTIO_F_NOTIFY_ON_EMPTY flag, but in fact it turned on
interrupts all the time.

Because we always process one buffer at a time, the inflight count is always 0
when call trigger_irq and so we always ignore VRING_AVAIL_F_NO_INTERRUPT from
the Guest.

It should be looking to see if there are more buffers in the Guest's queue:
if it's empty, then we force an interrupt.

This makes little difference, since we usually have an empty queue; but
that's the subject of another patch.

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent a6c372de

Documentation/lguest/lguest.c

+1 −7
Original line number Original line Diff line number Diff line
@@ -172,9 +172,6 @@ struct virtqueue 
	/* The routine to call when the Guest pings us, or timeout. */

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

	void (*handle_output)(struct virtqueue *me, bool timeout);

	void (*handle_output)(struct virtqueue *me, bool timeout);





	/* Outstanding buffers */

	unsigned int inflight;



	/* Is this blocked awaiting a timer? */

	/* Is this blocked awaiting a timer? */

	bool blocked;

	bool blocked;

};

};
@@ -699,7 +696,6 @@ static unsigned get_vq_desc(struct virtqueue *vq, 
			errx(1, "Looped descriptor");

			errx(1, "Looped descriptor");

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

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





	vq->inflight++;

	return head;

	return head;

}

}
@@ -717,7 +713,6 @@ static void add_used(struct virtqueue *vq, unsigned int head, int len) 
	/* Make sure buffer is written before we update index. */

	/* Make sure buffer is written before we update index. */

	wmb();

	wmb();

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

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

	vq->inflight--;

}

}





/* This actually sends the interrupt for this virtqueue */

/* This actually sends the interrupt for this virtqueue */
@@ -727,7 +722,7 @@ static void trigger_irq(struct virtqueue *vq) 




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

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

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

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

	    && vq->inflight)

	    && lg_last_avail(vq) != vq->vring.avail->idx)

		return;

		return;





	/* Send the Guest an interrupt tell them we used something up. */

	/* Send the Guest an interrupt tell them we used something up. */
@@ -1171,7 +1166,6 @@ static void add_virtqueue(struct device *dev, unsigned int num_descs, 
	vq->next = NULL;

	vq->next = NULL;

	vq->last_avail_idx = 0;

	vq->last_avail_idx = 0;

	vq->dev = dev;

	vq->dev = dev;

	vq->inflight = 0;

	vq->blocked = false;

	vq->blocked = false;





	/* Initialize the configuration. */

	/* Initialize the configuration. */