IB/qib: Decode path MTU optimization

Store both the encoded and decoded MTU in the QP structure as a minor
optimization for UC/RC receive routines.
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@qlogic.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/infiniband/hw/qib/qib_qp.c

@@ -765,8 +765,10 @@ int qib_modify_qp(struct ib_qp *ibqp, struct ib_qp_attr *attr,
 		}
 	}
 
-	if (attr_mask & IB_QP_PATH_MTU)
+	if (attr_mask & IB_QP_PATH_MTU) {
 		qp->path_mtu = pmtu;
+		qp->pmtu = ib_mtu_enum_to_int(pmtu);
+	}
 
 	if (attr_mask & IB_QP_RETRY_CNT) {
 		qp->s_retry_cnt = attr->retry_cnt;

drivers/infiniband/hw/qib/qib_rc.c

@@ -239,7 +239,7 @@ int qib_make_rc_req(struct qib_qp *qp)
 	u32 len;
 	u32 bth0;
 	u32 bth2;
-	u32 pmtu = ib_mtu_enum_to_int(qp->path_mtu);
+	u32 pmtu = qp->pmtu;
 	char newreq;
 	unsigned long flags;
 	int ret = 0;
@@ -1732,7 +1732,7 @@ static int qib_rc_rcv_error(struct qib_other_headers *ohdr,
 		 * same request.
 		 */
 		offset = ((psn - e->psn) & QIB_PSN_MASK) *
-			ib_mtu_enum_to_int(qp->path_mtu);
+			qp->pmtu;
 		len = be32_to_cpu(reth->length);
 		if (unlikely(offset + len != e->rdma_sge.sge_length))
 			goto unlock_done;
@@ -1876,7 +1876,7 @@ void qib_rc_rcv(struct qib_ctxtdata *rcd, struct qib_ib_header *hdr,
 	u32 psn;
 	u32 pad;
 	struct ib_wc wc;
-	u32 pmtu = ib_mtu_enum_to_int(qp->path_mtu);
+	u32 pmtu = qp->pmtu;
 	int diff;
 	struct ib_reth *reth;
 	unsigned long flags;

drivers/infiniband/hw/qib/qib_uc.c

@@ -51,7 +51,7 @@ int qib_make_uc_req(struct qib_qp *qp)
 	u32 hwords;
 	u32 bth0;
 	u32 len;
-	u32 pmtu = ib_mtu_enum_to_int(qp->path_mtu);
+	u32 pmtu = qp->pmtu;
 	int ret = 0;
 
 	spin_lock_irqsave(&qp->s_lock, flags);
@@ -249,7 +249,7 @@ void qib_uc_rcv(struct qib_ibport *ibp, struct qib_ib_header *hdr,
 	u32 psn;
 	u32 pad;
 	struct ib_wc wc;
-	u32 pmtu = ib_mtu_enum_to_int(qp->path_mtu);
+	u32 pmtu = qp->pmtu;
 	struct ib_reth *reth;
 	int ret;
 

drivers/infiniband/hw/qib/qib_verbs.h

@@ -485,6 +485,7 @@ struct qib_qp {
 	u8 alt_timeout;         /* Alternate path timeout for this QP */
 	u8 port_num;
 	enum ib_mtu path_mtu;
+	u32 pmtu;		/* decoded from path_mtu */
 	u32 remote_qpn;
 	u32 qkey;               /* QKEY for this QP (for UD or RD) */
 	u32 s_size;             /* send work queue size */