jme: Prevent possible read re-order error

Adding read memory barrier in between flag reading and data reading of
receive descriptors. This prevents the data being read before hardware
complete writing informations.

Reported-by: Stefan Hajnoczi <stefanha@gmail.com>

diff --git a/jme.c b/jme.c
index 0ea0da32d7d8fd00cb0c39a54f6d11f3913f758d..095f8998714f599784354358169eb5b7fc320755 100644 (file)
--- a/jme.c
+++ b/jme.c
@@ -989,6 +989,7 @@ jme_process_receive(struct jme_adapter *jme, int limit)
                        goto out;
                --limit;
 
                        goto out;
                --limit;
 

+               rmb();

                desccnt = rxdesc->descwb.desccnt & RXWBDCNT_DCNT;
 
                if (unlikely(desccnt > 1 ||
                desccnt = rxdesc->descwb.desccnt & RXWBDCNT_DCNT;
 
                if (unlikely(desccnt > 1 ||