IB/srpt: Cache global L_Key

This patch is a micro-optimization for the hot path.
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/ulp/srpt/ib_srpt.c

@@ -766,7 +766,7 @@ static int srpt_post_recv(struct srpt_device *sdev,
 	BUG_ON(!sdev);
 	list.addr = ioctx->ioctx.dma;
 	list.length = srp_max_req_size;
-	list.lkey = sdev->pd->local_dma_lkey;
+	list.lkey = sdev->lkey;
 
 	ioctx->ioctx.cqe.done = srpt_recv_done;
 	wr.wr_cqe = &ioctx->ioctx.cqe;
@@ -2343,7 +2343,7 @@ static void srpt_queue_response(struct se_cmd *cmd)
 
 	sge.addr = ioctx->ioctx.dma;
 	sge.length = resp_len;
-	sge.lkey = sdev->pd->local_dma_lkey;
+	sge.lkey = sdev->lkey;
 
 	ioctx->ioctx.cqe.done = srpt_send_done;
 	send_wr.next = NULL;
@@ -2491,6 +2491,8 @@ static void srpt_add_one(struct ib_device *device)
 	if (IS_ERR(sdev->pd))
 		goto free_dev;
 
+	sdev->lkey = sdev->pd->local_dma_lkey;
+
 	sdev->srq_size = min(srpt_srq_size, sdev->device->attrs.max_srq_wr);
 
 	srq_attr.event_handler = srpt_srq_event;

drivers/infiniband/ulp/srpt/ib_srpt.h

@@ -343,7 +343,7 @@ struct srpt_port {
  * struct srpt_device - Information associated by SRPT with a single HCA.
  * @device:        Backpointer to the struct ib_device managed by the IB core.
  * @pd:            IB protection domain.
- * @mr:            L_Key (local key) with write access to all local memory.
+ * @lkey:          L_Key (local key) with write access to all local memory.
  * @srq:           Per-HCA SRQ (shared receive queue).
  * @cm_id:         Connection identifier.
  * @srq_size:      SRQ size.
@@ -358,6 +358,7 @@ struct srpt_port {
 struct srpt_device {
 	struct ib_device	*device;
 	struct ib_pd		*pd;
+	u32			lkey;
 	struct ib_srq		*srq;
 	struct ib_cm_id		*cm_id;
 	int			srq_size;