1 files changed, 61 insertions, 15 deletions

diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
index b88515936e4b..c8f3f72ab20e 100644
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -75,6 +75,8 @@ struct virtio_chan {
         struct p9_client *client;
         struct virtio_device *vdev;
         struct virtqueue *vq;
+        int ring_bufs_avail;
+        wait_queue_head_t *vc_wq;
 
         /* Scatterlist: can be too big for stack. */
         struct scatterlist sg[VIRTQUEUE_NUM];
@@ -134,16 +136,30 @@ static void req_done(struct virtqueue *vq)
         struct p9_fcall *rc;
         unsigned int len;
         struct p9_req_t *req;
+        unsigned long flags;
 
         P9_DPRINTK(P9_DEBUG_TRANS, ": request done\n");
 
-        while ((rc = virtqueue_get_buf(chan->vq, &len)) != NULL) {
-                P9_DPRINTK(P9_DEBUG_TRANS, ": rc %p\n", rc);
-                P9_DPRINTK(P9_DEBUG_TRANS, ": lookup tag %d\n", rc->tag);
-                req = p9_tag_lookup(chan->client, rc->tag);
-                req->status = REQ_STATUS_RCVD;
-                p9_client_cb(chan->client, req);
-        }
+        do {
+                spin_lock_irqsave(&chan->lock, flags);
+                rc = virtqueue_get_buf(chan->vq, &len);
+
+                if (rc != NULL) {
+                        if (!chan->ring_bufs_avail) {
+                                chan->ring_bufs_avail = 1;
+                                wake_up(chan->vc_wq);
+                        }
+                        spin_unlock_irqrestore(&chan->lock, flags);
+                        P9_DPRINTK(P9_DEBUG_TRANS, ": rc %p\n", rc);
+                        P9_DPRINTK(P9_DEBUG_TRANS, ": lookup tag %d\n",
+                                        rc->tag);
+                        req = p9_tag_lookup(chan->client, rc->tag);
+                        req->status = REQ_STATUS_RCVD;
+                        p9_client_cb(chan->client, req);
+                } else {
+                        spin_unlock_irqrestore(&chan->lock, flags);
+                }
+        } while (rc != NULL);
 }
 
 /**
@@ -199,23 +215,43 @@ p9_virtio_request(struct p9_client *client, struct p9_req_t *req)
         int in, out;
         struct virtio_chan *chan = client->trans;
         char *rdata = (char *)req->rc+sizeof(struct p9_fcall);
+        unsigned long flags;
+        int err;
 
         P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request\n");
 
+req_retry:
+        req->status = REQ_STATUS_SENT;
+
+        spin_lock_irqsave(&chan->lock, flags);
         out = pack_sg_list(chan->sg, 0, VIRTQUEUE_NUM, req->tc->sdata,
                                                                 req->tc->size);
         in = pack_sg_list(chan->sg, out, VIRTQUEUE_NUM-out, rdata,
                                                                 client->msize);
 
-        req->status = REQ_STATUS_SENT;
-
-        if (virtqueue_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;
+        err = virtqueue_add_buf(chan->vq, chan->sg, out, in, req->tc);
+        if (err < 0) {
+                if (err == -ENOSPC) {
+                        chan->ring_bufs_avail = 0;
+                        spin_unlock_irqrestore(&chan->lock, flags);
+                        err = wait_event_interruptible(*chan->vc_wq,
+                                                        chan->ring_bufs_avail);
+                        if (err  == -ERESTARTSYS)
+                                return err;
+
+                        P9_DPRINTK(P9_DEBUG_TRANS, "9p:Retry virtio request\n");
+                        goto req_retry;
+                } else {
+                        spin_unlock_irqrestore(&chan->lock, flags);
+                        P9_DPRINTK(P9_DEBUG_TRANS,
+                                        "9p debug: "
+                                        "virtio rpc add_buf returned failure");
+                        return -EIO;
+                }
         }
 
         virtqueue_kick(chan->vq);
+        spin_unlock_irqrestore(&chan->lock, flags);
 
         P9_DPRINTK(P9_DEBUG_TRANS, "9p debug: virtio request kicked\n");
         return 0;
@@ -290,14 +326,23 @@ static int p9_virtio_probe(struct virtio_device *vdev)
         chan->tag_len = tag_len;
         err = sysfs_create_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr);
         if (err) {
-                kfree(tag);
-                goto out_free_vq;
+                goto out_free_tag;
         }
+        chan->vc_wq = kmalloc(sizeof(wait_queue_head_t), GFP_KERNEL);
+        if (!chan->vc_wq) {
+                err = -ENOMEM;
+                goto out_free_tag;
+        }
+        init_waitqueue_head(chan->vc_wq);
+        chan->ring_bufs_avail = 1;
+
         mutex_lock(&virtio_9p_lock);
         list_add_tail(&chan->chan_list, &virtio_chan_list);
         mutex_unlock(&virtio_9p_lock);
         return 0;
 
+out_free_tag:
+        kfree(tag);
 out_free_vq:
         vdev->config->del_vqs(vdev);
         kfree(chan);
@@ -371,6 +416,7 @@ static void p9_virtio_remove(struct virtio_device *vdev)
         mutex_unlock(&virtio_9p_lock);
         sysfs_remove_file(&(vdev->dev.kobj), &dev_attr_mount_tag.attr);
         kfree(chan->tag);
+        kfree(chan->vc_wq);
         kfree(chan);
 
 }