scsi: lpfc: Add missing memory barrier

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>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/lpfc/lpfc_sli.c b/drivers/scsi/lpfc/lpfc_sli.c
index 7e11cbdb238ca6c7fef8890a56c614144beb1291..3a8470d55af51cf676f4bd228f72084d03fa526d 100644 (file)
--- 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;