[net/9p]Serialize virtqueue operations to make VirtIO transport SMP safe.

Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

1 files changed, 24 insertions, 10 deletions

diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
index b88515936e4b..8ae08596aad8 100644
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -134,16 +134,24 @@ 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);
+                spin_unlock_irqrestore(&chan->lock, flags);
+
+                if (rc != 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);
+                }
+        } while (rc != NULL);
 }
 
 /**
@@ -199,23 +207,29 @@ 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->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) {
+        err = virtqueue_add_buf(chan->vq, chan->sg, out, in, req->tc);
+        if (err < 0) {
+                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;