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-rw-r--r--drivers/scsi/lpfc/lpfc_sli.c21
1 files changed, 21 insertions, 0 deletions
diff --git a/drivers/scsi/lpfc/lpfc_sli.c b/drivers/scsi/lpfc/lpfc_sli.c
index 572579f87de4..90861416b9e9 100644
--- a/drivers/scsi/lpfc/lpfc_sli.c
+++ b/drivers/scsi/lpfc/lpfc_sli.c
@@ -263,6 +263,16 @@ 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;
}
@@ -368,6 +378,17 @@ 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;
}