enic: move wmb closer to where needed: before writing posted_index to hw
Signed-off-by: Scott Feldman <scofeldm@cisco.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/enic/vnic_rq.h b/drivers/net/enic/vnic_rq.h
index 82bfca6..fd0ef66 100644
--- a/drivers/net/enic/vnic_rq.h
+++ b/drivers/net/enic/vnic_rq.h
@@ -132,8 +132,15 @@
#define VNIC_RQ_RETURN_RATE 0xf /* keep 2^n - 1 */
#endif
- if ((buf->index & VNIC_RQ_RETURN_RATE) == 0)
+ if ((buf->index & VNIC_RQ_RETURN_RATE) == 0) {
+ /* Adding write memory barrier prevents compiler and/or CPU
+ * reordering, thus avoiding descriptor posting before
+ * descriptor is initialized. Otherwise, hardware can read
+ * stale descriptor fields.
+ */
+ wmb();
iowrite32(buf->index, &rq->ctrl->posted_index);
+ }
}
static inline void vnic_rq_return_descs(struct vnic_rq *rq, unsigned int count)