[net/9p] Set the condition just before waking up.

Given that the sprious wake-ups are common, we need to move the
condition setting right next to the wake_up().  After setting the condition
to req->status = REQ_STATUS_RCVD, sprious wakeups may cause the
virtqueue back on the free list for someone else to use.
This may result in kernel panic while relasing the pinned pages
in p9_release_req_pages().

Also rearranged the while loop in req_done() for better redability.

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

diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
index 961e025957ae99783e1c95068a5fcde812b6e941..cb98af9367ab356e0299f5e1c89123741628e19f 100644 (file)
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -141,33 +141,33 @@ static void req_done(struct virtqueue *vq)
 
        P9_DPRINTK(P9_DEBUG_TRANS, ": request done\n");
 
-       do {
+       while (1) {
                spin_lock_irqsave(&chan->lock, flags);
                rc = virtqueue_get_buf(chan->vq, &len);
 
-               if (rc != NULL) {
-                       chan->ring_bufs_avail = 1;
-                       spin_unlock_irqrestore(&chan->lock, flags);
-                       /* Wakeup if anyone waiting for VirtIO ring space. */
-                       wake_up(chan->vc_wq);
-                       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;
-                       if (req->tc->private) {
-                               struct trans_rpage_info *rp = req->tc->private;
-                               /*Release pages */
-                               p9_release_req_pages(rp);
-                               if (rp->rp_alloc)
-                                       kfree(rp);
-                               req->tc->private = NULL;
-                       }
-                       p9_client_cb(chan->client, req);
-               } else {
+               if (rc == NULL) {
                        spin_unlock_irqrestore(&chan->lock, flags);
+                       break;
                }
-       } while (rc != NULL);
+
+               chan->ring_bufs_avail = 1;
+               spin_unlock_irqrestore(&chan->lock, flags);
+               /* Wakeup if anyone waiting for VirtIO ring space. */
+               wake_up(chan->vc_wq);
+               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);
+               if (req->tc->private) {
+                       struct trans_rpage_info *rp = req->tc->private;
+                       /*Release pages */
+                       p9_release_req_pages(rp);
+                       if (rp->rp_alloc)
+                               kfree(rp);
+                       req->tc->private = NULL;
+               }
+               req->status = REQ_STATUS_RCVD;
+               p9_client_cb(chan->client, req);
+       }
 }
 
 /**