scsi: lpfc: Add missing memory barrier

[ Upstream commit 6b3b3bdb83b4ad51252d21bb13596db879e51850 ]

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>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/scsi/lpfc/lpfc_sli.c b/drivers/scsi/lpfc/lpfc_sli.c
index 2d4f4b58dcfa2b0c71b55bac03632777ec50c24a..beec755a56c6907afe90c906c27d8c9bdf0281be 100644 (file)
--- a/drivers/scsi/lpfc/lpfc_sli.c
+++ b/drivers/scsi/lpfc/lpfc_sli.c
@@ -119,6 +119,8 @@ 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;