diff options
| -rw-r--r-- | drivers/scsi/lpfc/lpfc_sli.c | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/drivers/scsi/lpfc/lpfc_sli.c b/drivers/scsi/lpfc/lpfc_sli.c index 6bb51f8e3c1b..393662c24df5 100644 --- a/drivers/scsi/lpfc/lpfc_sli.c +++ b/drivers/scsi/lpfc/lpfc_sli.c @@ -265,6 +265,16 @@ lpfc_sli4_eq_get(struct lpfc_queue *q) return NULL; q->hba_index = idx; + + /* + * insert barrier for instruction interlock : data from the hardware + * must have the valid bit checked before it can be copied and acted + * upon. Given what was seen in lpfc_sli4_cq_get() of speculative + * instructions allowing action on content before valid bit checked, + * add barrier here as well. May not be needed as "content" is a + * single 32-bit entity here (vs multi word structure for cq's). + */ + mb(); return eqe; } @@ -370,6 +380,17 @@ lpfc_sli4_cq_get(struct lpfc_queue *q) cqe = q->qe[q->hba_index].cqe; q->hba_index = idx; + + /* + * insert barrier for instruction interlock : data from the hardware + * must have the valid bit checked before it can be copied and acted + * upon. Speculative instructions were allowing a bcopy at the start + * of lpfc_sli4_fp_handle_wcqe(), which is called immediately + * after our return, to copy data before the valid bit check above + * was done. As such, some of the copied data was stale. The barrier + * ensures the check is before any data is copied. + */ + mb(); return cqe; } |