[PATCH 2.6.35 1/3] RDMA/cxgb4: Don't call abort_connection() for active connect failures.

[PATCH 2.6.35 1/3] RDMA/cxgb4: Don't call abort_connection() for active connect failures.

[Steve Wise]

Signed-off-by: Steve Wise <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
---

 drivers/infiniband/hw/cxgb4/cm.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/drivers/infiniband/hw/cxgb4/cm.c b/drivers/infiniband/hw/cxgb4/cm.c
index 30ce0a8..3e15a07 100644
--- a/drivers/infiniband/hw/cxgb4/cm.c
+++ b/drivers/infiniband/hw/cxgb4/cm.c
@@ -969,7 +969,8 @@ static void process_mpa_reply(struct c4iw_ep *ep, struct sk_buff *skb)
 		goto err;
 	goto out;
 err:
-	abort_connection(ep, skb, GFP_KERNEL);
+	state_set(&ep->com, ABORTING);
+	send_abort(ep, skb, GFP_KERNEL);
 out:
 	connect_reply_upcall(ep, err);
 	return;

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[PATCH 2.6.35 2/3] RDMA/cxgb4: Support variable sized work requests.

[Steve Wise]

T4 EQ entries are in multiples of 64B.  Currently the RDMA SQ and RQ
use fixed sized entries composed of 4 EQ entries for the SQ and 2 EQ
entries for the RQ.  For optimial latency with small IO, we need to
change this so the HW only needs to DMA the EQ entries actually used by
a given work request.

Implementation:

- add wq_pidx counter to track where we are in the EQ.  cidx/pidx are
used for the sw sq/rq tracking and flow control.

- the variable part of work requests is the SGL.  Add new functions to
build the SGL and/or immediate data directly in the EQ memory wrapping
when needed.

- adjust the min burst size for the EQ contexts to 64B.

Signed-off-by: Steve Wise <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
---

 drivers/infiniband/hw/cxgb4/qp.c |  220 ++++++++++++++++++++------------------
 drivers/infiniband/hw/cxgb4/t4.h |   32 +++---
 2 files changed, 130 insertions(+), 122 deletions(-)

diff --git a/drivers/infiniband/hw/cxgb4/qp.c b/drivers/infiniband/hw/cxgb4/qp.c
index 0c28ed1..7d87fe5 100644
--- a/drivers/infiniband/hw/cxgb4/qp.c
+++ b/drivers/infiniband/hw/cxgb4/qp.c
@@ -162,7 +162,7 @@ static int create_qp(struct c4iw_rdev *rdev, struct t4_wq *wq,
 	res->u.sqrq.dcaen_to_eqsize = cpu_to_be32(
 		V_FW_RI_RES_WR_DCAEN(0) |
 		V_FW_RI_RES_WR_DCACPU(0) |
-		V_FW_RI_RES_WR_FBMIN(3) |
+		V_FW_RI_RES_WR_FBMIN(2) |
 		V_FW_RI_RES_WR_FBMAX(3) |
 		V_FW_RI_RES_WR_CIDXFTHRESHO(0) |
 		V_FW_RI_RES_WR_CIDXFTHRESH(0) |
@@ -185,7 +185,7 @@ static int create_qp(struct c4iw_rdev *rdev, struct t4_wq *wq,
 	res->u.sqrq.dcaen_to_eqsize = cpu_to_be32(
 		V_FW_RI_RES_WR_DCAEN(0) |
 		V_FW_RI_RES_WR_DCACPU(0) |
-		V_FW_RI_RES_WR_FBMIN(3) |
+		V_FW_RI_RES_WR_FBMIN(2) |
 		V_FW_RI_RES_WR_FBMAX(3) |
 		V_FW_RI_RES_WR_CIDXFTHRESHO(0) |
 		V_FW_RI_RES_WR_CIDXFTHRESH(0) |
@@ -235,12 +235,78 @@ err1:
 	return -ENOMEM;
 }
 
-static int build_rdma_send(union t4_wr *wqe, struct ib_send_wr *wr, u8 *len16)
+static int build_immd(struct t4_sq *sq, struct fw_ri_immd *immdp,
+		      struct ib_send_wr *wr, int max, u32 *plenp)
 {
+	u8 *dstp, *srcp;
+	u32 plen = 0;
 	int i;
+	int rem, len;
+
+	dstp = (u8 *)immdp->data;
+	for (i = 0; i < wr->num_sge; i++) {
+		if ((plen + wr->sg_list[i].length) > max)
+			return -EMSGSIZE;
+		srcp = (u8 *)(unsigned long)wr->sg_list[i].addr;
+		plen += wr->sg_list[i].length;
+		rem = wr->sg_list[i].length;
+		while (rem) {
+			if (dstp == (u8 *)&sq->queue[sq->size])
+				dstp = (u8 *)sq->queue;
+			if (rem <= (u8 *)&sq->queue[sq->size] - dstp)
+				len = rem;
+			else
+				len = (u8 *)&sq->queue[sq->size] - dstp;
+			memcpy(dstp, srcp, len);
+			dstp += len;
+			srcp += len;
+			rem -= len;
+		}
+	}
+	immdp->op = FW_RI_DATA_IMMD;
+	immdp->r1 = 0;
+	immdp->r2 = 0;
+	immdp->immdlen = cpu_to_be32(plen);
+	*plenp = plen;
+	return 0;
+}
+
+static int build_isgl(__be64 *queue_start, __be64 *queue_end,
+		      struct fw_ri_isgl *isglp, struct ib_sge *sg_list,
+		      int num_sge, u32 *plenp)
+
+{
+	int i;
+	u32 plen = 0;
+	__be64 *flitp = (__be64 *)isglp->sge;
+
+	for (i = 0; i < num_sge; i++) {
+		if ((plen + sg_list[i].length) < plen)
+			return -EMSGSIZE;
+		plen += sg_list[i].length;
+		*flitp = cpu_to_be64(((u64)sg_list[i].lkey << 32) |
+				     sg_list[i].length);
+		if (++flitp == queue_end)
+			flitp = queue_start;
+		*flitp = cpu_to_be64(sg_list[i].addr);
+		if (++flitp == queue_end)
+			flitp = queue_start;
+	}
+	isglp->op = FW_RI_DATA_ISGL;
+	isglp->r1 = 0;
+	isglp->nsge = cpu_to_be16(num_sge);
+	isglp->r2 = 0;
+	if (plenp)
+		*plenp = plen;
+	return 0;
+}
+
+static int build_rdma_send(struct t4_sq *sq, union t4_wr *wqe,
+			   struct ib_send_wr *wr, u8 *len16)
+{
 	u32 plen;
 	int size;
-	u8 *datap;
+	int ret;
 
 	if (wr->num_sge > T4_MAX_SEND_SGE)
 		return -EINVAL;
@@ -267,43 +333,23 @@ static int build_rdma_send(union t4_wr *wqe, struct ib_send_wr *wr, u8 *len16)
 	default:
 		return -EINVAL;
 	}
+
 	plen = 0;
 	if (wr->num_sge) {
 		if (wr->send_flags & IB_SEND_INLINE) {
-			datap = (u8 *)wqe->send.u.immd_src[0].data;
-			for (i = 0; i < wr->num_sge; i++) {
-				if ((plen + wr->sg_list[i].length) >
-				    T4_MAX_SEND_INLINE) {
-					return -EMSGSIZE;
-				}
-				plen += wr->sg_list[i].length;
-				memcpy(datap,
-				     (void *)(unsigned long)wr->sg_list[i].addr,
-				     wr->sg_list[i].length);
-				datap += wr->sg_list[i].length;
-			}
-			wqe->send.u.immd_src[0].op = FW_RI_DATA_IMMD;
-			wqe->send.u.immd_src[0].r1 = 0;
-			wqe->send.u.immd_src[0].r2 = 0;
-			wqe->send.u.immd_src[0].immdlen = cpu_to_be32(plen);
+			ret = build_immd(sq, wqe->send.u.immd_src, wr,
+					 T4_MAX_SEND_INLINE, &plen);
+			if (ret)
+				return ret;
 			size = sizeof wqe->send + sizeof(struct fw_ri_immd) +
 			       plen;
 		} else {
-			for (i = 0; i < wr->num_sge; i++) {
-				if ((plen + wr->sg_list[i].length) < plen)
-					return -EMSGSIZE;
-				plen += wr->sg_list[i].length;
-				wqe->send.u.isgl_src[0].sge[i].stag =
-					cpu_to_be32(wr->sg_list[i].lkey);
-				wqe->send.u.isgl_src[0].sge[i].len =
-					cpu_to_be32(wr->sg_list[i].length);
-				wqe->send.u.isgl_src[0].sge[i].to =
-					cpu_to_be64(wr->sg_list[i].addr);
-			}
-			wqe->send.u.isgl_src[0].op = FW_RI_DATA_ISGL;
-			wqe->send.u.isgl_src[0].r1 = 0;
-			wqe->send.u.isgl_src[0].nsge = cpu_to_be16(wr->num_sge);
-			wqe->send.u.isgl_src[0].r2 = 0;
+			ret = build_isgl((__be64 *)sq->queue,
+					 (__be64 *)&sq->queue[sq->size],
+					 wqe->send.u.isgl_src,
+					 wr->sg_list, wr->num_sge, &plen);
+			if (ret)
+				return ret;
 			size = sizeof wqe->send + sizeof(struct fw_ri_isgl) +
 			       wr->num_sge * sizeof(struct fw_ri_sge);
 		}
@@ -313,62 +359,40 @@ static int build_rdma_send(union t4_wr *wqe, struct ib_send_wr *wr, u8 *len16)
 		wqe->send.u.immd_src[0].r2 = 0;
 		wqe->send.u.immd_src[0].immdlen = 0;
 		size = sizeof wqe->send + sizeof(struct fw_ri_immd);
+		plen = 0;
 	}
 	*len16 = DIV_ROUND_UP(size, 16);
 	wqe->send.plen = cpu_to_be32(plen);
 	return 0;
 }
 
-static int build_rdma_write(union t4_wr *wqe, struct ib_send_wr *wr, u8 *len16)
+static int build_rdma_write(struct t4_sq *sq, union t4_wr *wqe,
+			    struct ib_send_wr *wr, u8 *len16)
 {
-	int i;
 	u32 plen;
 	int size;
-	u8 *datap;
+	int ret;
 
-	if (wr->num_sge > T4_MAX_WRITE_SGE)
+	if (wr->num_sge > T4_MAX_SEND_SGE)
 		return -EINVAL;
 	wqe->write.r2 = 0;
 	wqe->write.stag_sink = cpu_to_be32(wr->wr.rdma.rkey);
 	wqe->write.to_sink = cpu_to_be64(wr->wr.rdma.remote_addr);
-	plen = 0;
 	if (wr->num_sge) {
 		if (wr->send_flags & IB_SEND_INLINE) {
-			datap = (u8 *)wqe->write.u.immd_src[0].data;
-			for (i = 0; i < wr->num_sge; i++) {
-				if ((plen + wr->sg_list[i].length) >
-				    T4_MAX_WRITE_INLINE) {
-					return -EMSGSIZE;
-				}
-				plen += wr->sg_list[i].length;
-				memcpy(datap,
-				     (void *)(unsigned long)wr->sg_list[i].addr,
-				     wr->sg_list[i].length);
-				datap += wr->sg_list[i].length;
-			}
-			wqe->write.u.immd_src[0].op = FW_RI_DATA_IMMD;
-			wqe->write.u.immd_src[0].r1 = 0;
-			wqe->write.u.immd_src[0].r2 = 0;
-			wqe->write.u.immd_src[0].immdlen = cpu_to_be32(plen);
+			ret = build_immd(sq, wqe->write.u.immd_src, wr,
+					 T4_MAX_WRITE_INLINE, &plen);
+			if (ret)
+				return ret;
 			size = sizeof wqe->write + sizeof(struct fw_ri_immd) +
 			       plen;
 		} else {
-			for (i = 0; i < wr->num_sge; i++) {
-				if ((plen + wr->sg_list[i].length) < plen)
-					return -EMSGSIZE;
-				plen += wr->sg_list[i].length;
-				wqe->write.u.isgl_src[0].sge[i].stag =
-					cpu_to_be32(wr->sg_list[i].lkey);
-				wqe->write.u.isgl_src[0].sge[i].len =
-					cpu_to_be32(wr->sg_list[i].length);
-				wqe->write.u.isgl_src[0].sge[i].to =
-					cpu_to_be64(wr->sg_list[i].addr);
-			}
-			wqe->write.u.isgl_src[0].op = FW_RI_DATA_ISGL;
-			wqe->write.u.isgl_src[0].r1 = 0;
-			wqe->write.u.isgl_src[0].nsge =
-						       cpu_to_be16(wr->num_sge);
-			wqe->write.u.isgl_src[0].r2 = 0;
+			ret = build_isgl((__be64 *)sq->queue,
+					 (__be64 *)&sq->queue[sq->size],
+					 wqe->write.u.isgl_src,
+					 wr->sg_list, wr->num_sge, &plen);
+			if (ret)
+				return ret;
 			size = sizeof wqe->write + sizeof(struct fw_ri_isgl) +
 			       wr->num_sge * sizeof(struct fw_ri_sge);
 		}
@@ -378,6 +402,7 @@ static int build_rdma_write(union t4_wr *wqe, struct ib_send_wr *wr, u8 *len16)
 		wqe->write.u.immd_src[0].r2 = 0;
 		wqe->write.u.immd_src[0].immdlen = 0;
 		size = sizeof wqe->write + sizeof(struct fw_ri_immd);
+		plen = 0;
 	}
 	*len16 = DIV_ROUND_UP(size, 16);
 	wqe->write.plen = cpu_to_be32(plen);
@@ -416,29 +441,13 @@ static int build_rdma_read(union t4_wr *wqe, struct ib_send_wr *wr, u8 *len16)
 static int build_rdma_recv(struct c4iw_qp *qhp, union t4_recv_wr *wqe,
 			   struct ib_recv_wr *wr, u8 *len16)
 {
-	int i;
-	int plen = 0;
+	int ret;
 
-	for (i = 0; i < wr->num_sge; i++) {
-		if ((plen + wr->sg_list[i].length) < plen)
-			return -EMSGSIZE;
-		plen += wr->sg_list[i].length;
-		wqe->recv.isgl.sge[i].stag =
-			cpu_to_be32(wr->sg_list[i].lkey);
-		wqe->recv.isgl.sge[i].len =
-			cpu_to_be32(wr->sg_list[i].length);
-		wqe->recv.isgl.sge[i].to =
-			cpu_to_be64(wr->sg_list[i].addr);
-	}
-	for (; i < T4_MAX_RECV_SGE; i++) {
-		wqe->recv.isgl.sge[i].stag = 0;
-		wqe->recv.isgl.sge[i].len = 0;
-		wqe->recv.isgl.sge[i].to = 0;
-	}
-	wqe->recv.isgl.op = FW_RI_DATA_ISGL;
-	wqe->recv.isgl.r1 = 0;
-	wqe->recv.isgl.nsge = cpu_to_be16(wr->num_sge);
-	wqe->recv.isgl.r2 = 0;
+	ret = build_isgl((__be64 *)qhp->wq.rq.queue,
+			 (__be64 *)&qhp->wq.rq.queue[qhp->wq.rq.size],
+			 &wqe->recv.isgl, wr->sg_list, wr->num_sge, NULL);
+	if (ret)
+		return ret;
 	*len16 = DIV_ROUND_UP(sizeof wqe->recv +
 			      wr->num_sge * sizeof(struct fw_ri_sge), 16);
 	return 0;
@@ -547,7 +556,9 @@ int c4iw_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
 			*bad_wr = wr;
 			break;
 		}
-		wqe = &qhp->wq.sq.queue[qhp->wq.sq.pidx];
+		wqe = (union t4_wr *)((u8 *)qhp->wq.sq.queue +
+		      qhp->wq.sq.wq_pidx * T4_EQ_ENTRY_SIZE);
+
 		fw_flags = 0;
 		if (wr->send_flags & IB_SEND_SOLICITED)
 			fw_flags |= FW_RI_SOLICITED_EVENT_FLAG;
@@ -564,12 +575,12 @@ int c4iw_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
 				swsqe->opcode = FW_RI_SEND;
 			else
 				swsqe->opcode = FW_RI_SEND_WITH_INV;
-			err = build_rdma_send(wqe, wr, &len16);
+			err = build_rdma_send(&qhp->wq.sq, wqe, wr, &len16);
 			break;
 		case IB_WR_RDMA_WRITE:
 			fw_opcode = FW_RI_RDMA_WRITE_WR;
 			swsqe->opcode = FW_RI_RDMA_WRITE;
-			err = build_rdma_write(wqe, wr, &len16);
+			err = build_rdma_write(&qhp->wq.sq, wqe, wr, &len16);
 			break;
 		case IB_WR_RDMA_READ:
 		case IB_WR_RDMA_READ_WITH_INV:
@@ -619,8 +630,8 @@ int c4iw_post_send(struct ib_qp *ibqp, struct ib_send_wr *wr,
 		     swsqe->opcode, swsqe->read_len);
 		wr = wr->next;
 		num_wrs--;
-		t4_sq_produce(&qhp->wq);
-		idx++;
+		t4_sq_produce(&qhp->wq, len16);
+		idx += DIV_ROUND_UP(len16*16, T4_EQ_ENTRY_SIZE);
 	}
 	if (t4_wq_db_enabled(&qhp->wq))
 		t4_ring_sq_db(&qhp->wq, idx);
@@ -656,7 +667,9 @@ int c4iw_post_receive(struct ib_qp *ibqp, struct ib_recv_wr *wr,
 			*bad_wr = wr;
 			break;
 		}
-		wqe = &qhp->wq.rq.queue[qhp->wq.rq.pidx];
+		wqe = (union t4_recv_wr *)((u8 *)qhp->wq.rq.queue +
+					   qhp->wq.rq.wq_pidx *
+					   T4_EQ_ENTRY_SIZE);
 		if (num_wrs)
 			err = build_rdma_recv(qhp, wqe, wr, &len16);
 		else
@@ -675,15 +688,12 @@ int c4iw_post_receive(struct ib_qp *ibqp, struct ib_recv_wr *wr,
 		wqe->recv.r2[1] = 0;
 		wqe->recv.r2[2] = 0;
 		wqe->recv.len16 = len16;
-		if (len16 < 5)
-			wqe->flits[8] = 0;
-
 		PDBG("%s cookie 0x%llx pidx %u\n", __func__,
 		     (unsigned long long) wr->wr_id, qhp->wq.rq.pidx);
-		t4_rq_produce(&qhp->wq);
+		t4_rq_produce(&qhp->wq, len16);
+		idx += DIV_ROUND_UP(len16*16, T4_EQ_ENTRY_SIZE);
 		wr = wr->next;
 		num_wrs--;
-		idx++;
 	}
 	if (t4_wq_db_enabled(&qhp->wq))
 		t4_ring_rq_db(&qhp->wq, idx);
diff --git a/drivers/infiniband/hw/cxgb4/t4.h b/drivers/infiniband/hw/cxgb4/t4.h
index 1057cb9..97798d4 100644
--- a/drivers/infiniband/hw/cxgb4/t4.h
+++ b/drivers/infiniband/hw/cxgb4/t4.h
@@ -65,10 +65,10 @@ struct t4_status_page {
 	u8 db_off;
 };
 
-#define T4_EQ_SIZE 64
+#define T4_EQ_ENTRY_SIZE 64
 
 #define T4_SQ_NUM_SLOTS 4
-#define T4_SQ_NUM_BYTES (T4_EQ_SIZE * T4_SQ_NUM_SLOTS)
+#define T4_SQ_NUM_BYTES (T4_EQ_ENTRY_SIZE * T4_SQ_NUM_SLOTS)
 #define T4_MAX_SEND_SGE ((T4_SQ_NUM_BYTES - sizeof(struct fw_ri_send_wr) - \
 			sizeof(struct fw_ri_isgl)) / sizeof(struct fw_ri_sge))
 #define T4_MAX_SEND_INLINE ((T4_SQ_NUM_BYTES - sizeof(struct fw_ri_send_wr) - \
@@ -84,7 +84,7 @@ struct t4_status_page {
 #define T4_MAX_FR_DEPTH (T4_MAX_FR_IMMD / sizeof(u64))
 
 #define T4_RQ_NUM_SLOTS 2
-#define T4_RQ_NUM_BYTES (T4_EQ_SIZE * T4_RQ_NUM_SLOTS)
+#define T4_RQ_NUM_BYTES (T4_EQ_ENTRY_SIZE * T4_RQ_NUM_SLOTS)
 #define T4_MAX_RECV_SGE 4
 
 union t4_wr {
@@ -97,20 +97,18 @@ union t4_wr {
 	struct fw_ri_fr_nsmr_wr fr;
 	struct fw_ri_inv_lstag_wr inv;
 	struct t4_status_page status;
-	__be64 flits[T4_EQ_SIZE / sizeof(__be64) * T4_SQ_NUM_SLOTS];
+	__be64 flits[T4_EQ_ENTRY_SIZE / sizeof(__be64) * T4_SQ_NUM_SLOTS];
 };
 
 union t4_recv_wr {
 	struct fw_ri_recv_wr recv;
 	struct t4_status_page status;
-	__be64 flits[T4_EQ_SIZE / sizeof(__be64) * T4_RQ_NUM_SLOTS];
+	__be64 flits[T4_EQ_ENTRY_SIZE / sizeof(__be64) * T4_RQ_NUM_SLOTS];
 };
 
 static inline void init_wr_hdr(union t4_wr *wqe, u16 wrid,
 			       enum fw_wr_opcodes opcode, u8 flags, u8 len16)
 {
-	int slots_used;
-
 	wqe->send.opcode = (u8)opcode;
 	wqe->send.flags = flags;
 	wqe->send.wrid = wrid;
@@ -118,12 +116,6 @@ static inline void init_wr_hdr(union t4_wr *wqe, u16 wrid,
 	wqe->send.r1[1] = 0;
 	wqe->send.r1[2] = 0;
 	wqe->send.len16 = len16;
-
-	slots_used = DIV_ROUND_UP(len16*16, T4_EQ_SIZE);
-	while (slots_used < T4_SQ_NUM_SLOTS) {
-		wqe->flits[slots_used * T4_EQ_SIZE / sizeof(__be64)] = 0;
-		slots_used++;
-	}
 }
 
 /* CQE/AE status codes */
@@ -289,6 +281,7 @@ struct t4_sq {
 	u16 size;
 	u16 cidx;
 	u16 pidx;
+	u16 wq_pidx;
 };
 
 struct t4_swrqe {
@@ -310,6 +303,7 @@ struct t4_rq {
 	u16 size;
 	u16 cidx;
 	u16 pidx;
+	u16 wq_pidx;
 };
 
 struct t4_wq {
@@ -340,11 +334,14 @@ static inline u32 t4_rq_avail(struct t4_wq *wq)
 	return wq->rq.size - 1 - wq->rq.in_use;
 }
 
-static inline void t4_rq_produce(struct t4_wq *wq)
+static inline void t4_rq_produce(struct t4_wq *wq, u8 len16)
 {
 	wq->rq.in_use++;
 	if (++wq->rq.pidx == wq->rq.size)
 		wq->rq.pidx = 0;
+	wq->rq.wq_pidx += DIV_ROUND_UP(len16*16, T4_EQ_ENTRY_SIZE);
+	if (wq->rq.wq_pidx >= wq->rq.size * T4_RQ_NUM_SLOTS)
+		wq->rq.wq_pidx %= wq->rq.size * T4_RQ_NUM_SLOTS;
 }
 
 static inline void t4_rq_consume(struct t4_wq *wq)
@@ -370,11 +367,14 @@ static inline u32 t4_sq_avail(struct t4_wq *wq)
 	return wq->sq.size - 1 - wq->sq.in_use;
 }
 
-static inline void t4_sq_produce(struct t4_wq *wq)
+static inline void t4_sq_produce(struct t4_wq *wq, u8 len16)
 {
 	wq->sq.in_use++;
 	if (++wq->sq.pidx == wq->sq.size)
 		wq->sq.pidx = 0;
+	wq->sq.wq_pidx += DIV_ROUND_UP(len16*16, T4_EQ_ENTRY_SIZE);
+	if (wq->sq.wq_pidx >= wq->sq.size * T4_SQ_NUM_SLOTS)
+		wq->sq.wq_pidx %= wq->sq.size * T4_SQ_NUM_SLOTS;
 }
 
 static inline void t4_sq_consume(struct t4_wq *wq)
@@ -386,14 +386,12 @@ static inline void t4_sq_consume(struct t4_wq *wq)
 
 static inline void t4_ring_sq_db(struct t4_wq *wq, u16 inc)
 {
-	inc *= T4_SQ_NUM_SLOTS;
 	wmb();
 	writel(QID(wq->sq.qid) | PIDX(inc), wq->db);
 }
 
 static inline void t4_ring_rq_db(struct t4_wq *wq, u16 inc)
 {
-	inc *= T4_RQ_NUM_SLOTS;
 	wmb();
 	writel(QID(wq->rq.qid) | PIDX(inc), wq->db);
 }

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[PATCH 2.6.35 3/3] RDMA/cxgb4: Avoid false GTS CIDX_INC overflows.

[Steve Wise]

The T4 IQ hw design assumes CIDX_INC credits will be returned on a regular
basis and always before the CIDX counter crosses over the PIDX counter.
For RDMA CQs, however, returning CIDX_INC credits is only needed and
desired when and if the CQ is armed for notification.  This can lead
to a GTS write returning credits that causes the HW to reject the
credit update because it causes CIDX to pass PIDX.  Once this happens,
the CIDX/PIDX counters get out of whack and an application can miss a
notification and get stuck blocked awaiting a notification.

To avoid this,  we allocate the HW IQ 2x times the requested size.
This seems to avoid the false overflow failures.  If we see more issues
with this, then we'll have to add code in the poll path to return credits
periodically like when the amount reaches 1/2 the queue depth).  I would
like to avoid this as it adds a PCI write transaction for applications
that never arm the CQ (like most MPIs).

Signed-off-by: Steve Wise <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
---

 drivers/infiniband/hw/cxgb4/cq.c |   25 ++++++++++++++++++++-----
 1 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/drivers/infiniband/hw/cxgb4/cq.c b/drivers/infiniband/hw/cxgb4/cq.c
index 2447f52..4311501 100644
--- a/drivers/infiniband/hw/cxgb4/cq.c
+++ b/drivers/infiniband/hw/cxgb4/cq.c
@@ -764,7 +764,7 @@ struct ib_cq *c4iw_create_cq(struct ib_device *ibdev, int entries,
 	struct c4iw_create_cq_resp uresp;
 	struct c4iw_ucontext *ucontext = NULL;
 	int ret;
-	size_t memsize;
+	size_t memsize, hwentries;
 	struct c4iw_mm_entry *mm, *mm2;
 
 	PDBG("%s ib_dev %p entries %d\n", __func__, ibdev, entries);
@@ -788,14 +788,29 @@ struct ib_cq *c4iw_create_cq(struct ib_device *ibdev, int entries,
 	 * entries must be multiple of 16 for HW.
 	 */
 	entries = roundup(entries, 16);
-	memsize = entries * sizeof *chp->cq.queue;
+
+	/*
+	 * Make actual HW queue 2x to avoid cdix_inc overflows.
+	 */
+	hwentries = entries * 2;
+
+	/*
+	 * Make HW queue at least 64 entries so GTS updates aren't too
+	 * frequent.
+	 */
+	if (hwentries < 64)
+		hwentries = 64;
+
+	memsize = hwentries * sizeof *chp->cq.queue;
 
 	/*
 	 * memsize must be a multiple of the page size if its a user cq.
 	 */
-	if (ucontext)
+	if (ucontext) {
 		memsize = roundup(memsize, PAGE_SIZE);
-	chp->cq.size = entries;
+		hwentries = memsize / sizeof *chp->cq.queue;
+	}
+	chp->cq.size = hwentries;
 	chp->cq.memsize = memsize;
 
 	ret = create_cq(&rhp->rdev, &chp->cq,
@@ -805,7 +820,7 @@ struct ib_cq *c4iw_create_cq(struct ib_device *ibdev, int entries,
 
 	chp->rhp = rhp;
 	chp->cq.size--;				/* status page */
-	chp->ibcq.cqe = chp->cq.size - 1;
+	chp->ibcq.cqe = entries - 2;
 	spin_lock_init(&chp->lock);
 	atomic_set(&chp->refcnt, 1);
 	init_waitqueue_head(&chp->wait);

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Re: [PATCH 2.6.35 2/3] RDMA/cxgb4: Support variable sized work requests.

[Roland Dreier]

 > T4 EQ entries are in multiples of 64B.  Currently the RDMA SQ and RQ
 > use fixed sized entries composed of 4 EQ entries for the SQ and 2 EQ
 > entries for the RQ.  For optimial latency with small IO, we need to
 > change this so the HW only needs to DMA the EQ entries actually used by
 > a given work request.

This seems not to be a fix, just an optimization -- so at this point for
2.6.36 I think.  Or am I wrong?
-- 
Roland Dreier <rolandd-FYB4Gu1CFyUAvxtiuMwx3w@public.gmane.org> || For corporate legal information go to:
http://www.cisco.com/web/about/doing_business/legal/cri/index.html
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Re: [PATCH 2.6.35 2/3] RDMA/cxgb4: Support variable sized work requests.

[Steve Wise]

Roland Dreier wrote:
>  > T4 EQ entries are in multiples of 64B.  Currently the RDMA SQ and RQ
>  > use fixed sized entries composed of 4 EQ entries for the SQ and 2 EQ
>  > entries for the RQ.  For optimial latency with small IO, we need to
>  > change this so the HW only needs to DMA the EQ entries actually used by
>  > a given work request.
>
> This seems not to be a fix, just an optimization -- so at this point for
> 2.6.36 I think.  Or am I wrong?
>   

You are correct...I was hoping since iw_cxgb4 is new to 2.6.35, we could 
still get this in.

But if you disagree, then 2.6.36...


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Re: [PATCH 2.6.35 2/3] RDMA/cxgb4: Support variable sized work requests.

[Roland Dreier]

Linus has been being a hard-ass this cycle about quieting things down
post -rc2.  So I'll hold off.
-- 
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Re: [PATCH 2.6.35 1/3] RDMA/cxgb4: Don't call abort_connection() for active connect failures.

[Roland Dreier]

thanks, applied
-- 
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Re: [PATCH 2.6.35 3/3] RDMA/cxgb4: Avoid false GTS CIDX_INC overflows.

[Roland Dreier]

thanks, applied
-- 
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Re: [PATCH 2.6.35 2/3] RDMA/cxgb4: Support variable sized work requests.

[Roland Dreier]

thanks, applied.
-- 
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