[net/9p]Serialize virtqueue operations to make VirtIO transport SMP safe.
Venkateswararao Jujjuri (JV) [Thu, 30 Sep 2010 01:06:54 +0000 (18:06 -0700)]
Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

net/9p/trans_virtio.c

index b885159..8ae0859 100644 (file)
@@ -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;