scsi: lpfc: Add missing memory barrier

Orabug: 25486030

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>
(cherry picked from commit 6b3b3bdb83b4ad51252d21bb13596db879e51850)
Signed-off-by: Brian Maly <brian.maly@oracle.com>

diff --git a/drivers/scsi/lpfc/lpfc_sli.c b/drivers/scsi/lpfc/lpfc_sli.c
index eb6ba904b1abf1804f5b5c42be425560f5045780..f743bc4cdef574986c7eb23ed81eda0410f9e108 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;