virtio: make add_buf return capacity remaining

This API change means that virtio_net can tell how much capacity
remains for buffers.  It's necessarily fuzzy, since
VIRTIO_RING_F_INDIRECT_DESC means we can fit any number of descriptors
in one, *if* we can kmalloc.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Dinesh Subhraveti <dineshs@us.ibm.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
index 9bf0b737aa51..53c139d31a21 100644
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -200,7 +200,7 @@ p9_virtio_request(struct p9_client *client, struct p9_req_t *req)
 
         req->status = REQ_STATUS_SENT;
 
-        if (chan->vq->vq_ops->add_buf(chan->vq, chan->sg, out, in, req->tc)) {
+        if (chan->vq->vq_ops->add_buf(chan->vq, chan->sg, out, in, req->tc) < 0) {
                 P9_DPRINTK(P9_DEBUG_TRANS,
                         "9p debug: virtio rpc add_buf returned failure");
                 return -EIO;