[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>

1 files changed, 22 insertions, 22 deletions

diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
index 961e025957ae..cb98af9367ab 100644
--- 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);
+        }
 }
 
 /**