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>
Signed-off-by: Guo-Fu Tseng <cooldavid@cooldavid.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/jme.c b/drivers/net/jme.c
index 0ea0da3..095f899 100644 (file)
--- a/drivers/net/jme.c
+++ b/drivers/net/jme.c
@@ -989,6 +989,7 @@ jme_process_receive(struct jme_adapter *jme, int limit)
                        goto out;
                --limit;
 
+               rmb();
                desccnt = rxdesc->descwb.desccnt & RXWBDCNT_DCNT;
 
                if (unlikely(desccnt > 1 ||