[PATCH v2 10/11] lpfc: Add missing memory barrier

[james.smart@broadcom.com (James Smart)]

On loosely ordered memory systems (PPC for example), the WQE elements
were being updated in memory, but not necessarily flushed before the
separate doorbell was written to hw which would cause hw to dma the
WQE element. Thus, the hardware occasionally received partially
updated WQE data.

Add the memory barrier after updating the WQE memory.

Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
---
v2:
  revised for checkpatch warning - comment before wmb()

 drivers/scsi/lpfc/lpfc_sli.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/scsi/lpfc/lpfc_sli.c b/drivers/scsi/lpfc/lpfc_sli.c
index d0ffcf3..5c8663f 100644
--- a/drivers/scsi/lpfc/lpfc_sli.c
+++ b/drivers/scsi/lpfc/lpfc_sli.c
@@ -120,6 +120,8 @@ lpfc_sli4_wq_put(struct lpfc_queue *q, union lpfc_wqe *wqe)
 	if (q->phba->sli3_options & LPFC_SLI4_PHWQ_ENABLED)
 		bf_set(wqe_wqid, &wqe->generic.wqe_com, q->queue_id);
 	lpfc_sli_pcimem_bcopy(wqe, temp_wqe, q->entry_size);
+	/* ensure WQE bcopy flushed before doorbell write */
+	wmb();
 
 	/* Update the host index before invoking device */
 	host_index = q->host_index;
-- 
2.5.0