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Commit 7ae4b866 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin Committed by Rusty Russell
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virtio: return correct capacity to users 



We can't rely on indirect buffers for capacity
calculations because they need a memory allocation
which might fail.  In particular, virtio_net can get
into this situation under stress, and it drops packets
and performs badly.

So return the number of buffers we can guarantee users.

Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Reported-By: default avatarKrishna Kumar2 <krkumar2@in.ibm.com>
parent dfd62d1d

drivers/virtio/virtio_ring.c

+0 −3
Original line number Diff line number Diff line
@@ -230,9 +230,6 @@ int virtqueue_add_buf_gfp(struct virtqueue *_vq, 
	pr_debug("Added buffer head %i to %p\n", head, vq);

	END_USE(vq);



	/* If we're indirect, we can fit many (assuming not OOM). */

	if (vq->indirect)

		return vq->num_free ? vq->vring.num : 0;

	return vq->num_free;

}

EXPORT_SYMBOL_GPL(virtqueue_add_buf_gfp);