vhost: fix signed/unsigned comparison

To detect that a sequence number is done, we are doing math on unsigned
integers so the result is unsigned too. Not what was intended for the <=
comparison. The result is user stuck forever in flush call.
Convert to int to fix this.

Further, get rid of ({}) to make code clearer.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 11 insertions, 7 deletions

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 38244f59cdd..ade0568c07a 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -97,22 +97,26 @@ void vhost_poll_stop(struct vhost_poll *poll)
         remove_wait_queue(poll->wqh, &poll->wait);
 }
 
+static bool vhost_work_seq_done(struct vhost_dev *dev, struct vhost_work *work,
+                                unsigned seq)
+{
+        int left;
+        spin_lock_irq(&dev->work_lock);
+        left = seq - work->done_seq;
+        spin_unlock_irq(&dev->work_lock);
+        return left <= 0;
+}
+
 static void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work)
 {
         unsigned seq;
-        int left;
         int flushing;
 
         spin_lock_irq(&dev->work_lock);
         seq = work->queue_seq;
         work->flushing++;
         spin_unlock_irq(&dev->work_lock);
-        wait_event(work->done, ({
-                   spin_lock_irq(&dev->work_lock);
-                   left = seq - work->done_seq <= 0;
-                   spin_unlock_irq(&dev->work_lock);
-                   left;
-        }));
+        wait_event(work->done, vhost_work_seq_done(dev, work, seq));
         spin_lock_irq(&dev->work_lock);
         flushing = --work->flushing;
         spin_unlock_irq(&dev->work_lock);