From 5484d6dfc4dd30b28fa3527fbae293427aba1835 Mon Sep 17 00:00:00 2001
From: Bart Van Assche <bvanassche@acm.org>
Date: Sat, 25 Jun 2011 19:13:50 +0000
Subject: [PATCH] ib_srpt: Eliminate the magic constant SRPT_DEF_SG_PER_WQE

git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@3626 d57e44dd-8a1f-0410-8b47-8ef2f437770f
---
 srpt/src/ib_srpt.c | 11 +++++++----
 srpt/src/ib_srpt.h |  5 +++--
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/srpt/src/ib_srpt.c b/srpt/src/ib_srpt.c
index 523a9f898..50970ca6a 100644
--- a/srpt/src/ib_srpt.c
+++ b/srpt/src/ib_srpt.c
@@ -2008,7 +2008,9 @@ static int srpt_create_ch_ib(struct srpt_rdma_ch *ch)
 	qp_init->sq_sig_type = IB_SIGNAL_REQ_WR;
 	qp_init->qp_type = IB_QPT_RC;
 	qp_init->cap.max_send_wr = srpt_sq_size;
-	qp_init->cap.max_send_sge = SRPT_DEF_SG_PER_WQE;
+	ch->max_sge = sdev->dev_attr.max_sge - 2;
+	BUG_ON(ch->max_sge <= 2);
+	qp_init->cap.max_send_sge = ch->max_sge;
 
 	ch->qp = ib_create_qp(sdev->pd, qp_init);
 	if (IS_ERR(ch->qp)) {
@@ -2684,10 +2686,12 @@ static int srpt_map_sg_to_ib_sge(struct srpt_rdma_ch *ch,
 	u32 dma_len;
 	int count, nrdma;
 	int i, j, k;
+	int max_sge;
 
 	BUG_ON(!ch);
 	BUG_ON(!ioctx);
 	BUG_ON(!scmnd);
+	max_sge = ch->max_sge;
 	dir = scst_cmd_get_data_direction(scmnd);
 	BUG_ON(dir == SCST_DATA_NONE);
 	/*
@@ -2715,8 +2719,7 @@ static int srpt_map_sg_to_ib_sge(struct srpt_rdma_ch *ch,
 	if (ioctx->rdma_ius && ioctx->n_rdma_ius)
 		nrdma = ioctx->n_rdma_ius;
 	else {
-		nrdma = (count + SRPT_DEF_SG_PER_WQE - 1) / SRPT_DEF_SG_PER_WQE
-			+ ioctx->n_rbuf;
+		nrdma = (count + max_sge - 1) / max_sge + ioctx->n_rbuf;
 
 		ioctx->rdma_ius = kzalloc(nrdma * sizeof *riu,
 					  scst_cmd_atomic(scmnd)
@@ -2771,7 +2774,7 @@ static int srpt_map_sg_to_ib_sge(struct srpt_rdma_ch *ch,
 
 			++riu->sge_cnt;
 
-			if (rsize > 0 && riu->sge_cnt == SRPT_DEF_SG_PER_WQE) {
+			if (rsize > 0 && riu->sge_cnt == max_sge) {
 				++ioctx->n_rdma;
 				riu->sge =
 				    kmalloc(riu->sge_cnt * sizeof *riu->sge,
diff --git a/srpt/src/ib_srpt.h b/srpt/src/ib_srpt.h
index 194a63001..5774120ba 100644
--- a/srpt/src/ib_srpt.h
+++ b/srpt/src/ib_srpt.h
@@ -108,7 +108,6 @@ enum {
 	SRP_LOGIN_RSP_MULTICHAN_MAINTAINED = 0x2,
 
 	SRPT_DEF_SG_TABLESIZE = 128,
-	SRPT_DEF_SG_PER_WQE = 16,
 
 	MIN_SRPT_SQ_SIZE = 16,
 	DEF_SRPT_SQ_SIZE = 4096,
@@ -208,7 +207,7 @@ struct srpt_tsk_mgmt {
 
 /**
  * struct srpt_send_ioctx - SRPT send I/O context.
- * @ioctx:     See above.
+ * @ioctx:       See above.
  * @ch:          Channel pointer.
  * @rdma_ius:    Array with information about the RDMA mapping.
  * @rbufs:       Pointer to SRP data buffer array.
@@ -275,6 +274,7 @@ enum rdma_ch_state {
  * @qp:            IB queue pair used for communicating over this channel.
  * @cq:            IB completion queue for this channel.
  * @rq_size:       IB receive queue size.
+ * @max_sge:       Maximum length of RDMA scatter list.
  * @sq_wr_avail:   number of work requests available in the send queue.
  * @sport:         pointer to the information of the HCA port used by this
  *                 channel.
@@ -304,6 +304,7 @@ struct srpt_rdma_ch {
 	struct ib_qp		*qp;
 	struct ib_cq		*cq;
 	int			rq_size;
+	int			max_sge;
 	int			sq_wr_avail;
 	struct srpt_port	*sport;
 	u8			i_port_id[16];