[PATCH v2 09/13] SoftiWarp transmit path

[Bernard Metzler <bmt-OA+xvbQnYDHMbYB6QlFGEg@public.gmane.org>]

Signed-off-by: Bernard Metzler <bmt-OA+xvbQnYDHMbYB6QlFGEg@public.gmane.org>
---
 drivers/infiniband/sw/siw/siw_qp_tx.c | 1341 +++++++++++++++++++++++++++++++++
 1 file changed, 1341 insertions(+)
 create mode 100644 drivers/infiniband/sw/siw/siw_qp_tx.c

diff --git a/drivers/infiniband/sw/siw/siw_qp_tx.c b/drivers/infiniband/sw/siw/siw_qp_tx.c
new file mode 100644
index 000000000000..554dd60c3572
--- /dev/null
+++ b/drivers/infiniband/sw/siw/siw_qp_tx.c
@@ -0,0 +1,1341 @@
+/*
+ * Software iWARP device driver for Linux
+ *
+ * Authors: Bernard Metzler <bmt-OA+xvbQnYDHMbYB6QlFGEg@public.gmane.org>
+ *
+ * Copyright (c) 2008-2017, IBM Corporation
+ *
+ * This software is available to you under a choice of one of two
+ * licenses. You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * BSD license below:
+ *
+ *   Redistribution and use in source and binary forms, with or
+ *   without modification, are permitted provided that the following
+ *   conditions are met:
+ *
+ *   - Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *
+ *   - Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *
+ *   - Neither the name of IBM nor the names of its contributors may be
+ *     used to endorse or promote products derived from this software without
+ *     specific prior written permission.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/net.h>
+#include <linux/scatterlist.h>
+#include <linux/highmem.h>
+#include <linux/llist.h>
+#include <net/sock.h>
+#include <net/tcp_states.h>
+#include <net/tcp.h>
+#include <linux/cpu.h>
+
+#include <rdma/iw_cm.h>
+#include <rdma/ib_verbs.h>
+#include <rdma/ib_smi.h>
+#include <rdma/ib_user_verbs.h>
+
+#include "siw.h"
+#include "siw_obj.h"
+#include "siw_cm.h"
+
+#include <linux/kthread.h>
+
+static bool zcopy_tx;
+module_param(zcopy_tx, bool, 0644);
+MODULE_PARM_DESC(zcopy_tx, "Zero copy user data transmit if possible");
+
+static int gso_seg_limit;
+module_param(gso_seg_limit, int, 0644);
+MODULE_PARM_DESC(gso_seg_limit, "Limit TCP GSO to value if set\n");
+
+static inline int siw_crc_txhdr(struct siw_iwarp_tx *ctx)
+{
+	crypto_shash_init(ctx->mpa_crc_hd);
+	return siw_crc_array(ctx->mpa_crc_hd, (u8 *)&ctx->pkt,
+			     ctx->ctrl_len);
+}
+
+#define MAX_HDR_INLINE					\
+	(((uint32_t)(sizeof(struct siw_rreq_pkt) -	\
+	sizeof(struct iwarp_send))) & 0xF8)
+
+static inline struct page *siw_get_pblpage(struct siw_mr *mr,
+					   u64 addr, int *idx)
+{
+	struct siw_pbl *pbl = mr->pbl;
+	u64 offset = addr - mr->mem.va;
+	u64 paddr = siw_pbl_get_buffer(pbl, offset, NULL, idx);
+
+	if (paddr)
+		return virt_to_page(paddr);
+	return NULL;
+}
+
+/*
+ * Copy short payload at provided destination address and
+ * update address pointer to the address behind data
+ * including potential padding
+ */
+static int siw_try_1seg(struct siw_iwarp_tx *c_tx, char *payload)
+{
+	struct siw_wqe *wqe = &c_tx->wqe_active;
+	struct siw_sge *sge = &wqe->sqe.sge[0];
+	u32 bytes = sge->length;
+
+	if (bytes > MAX_HDR_INLINE || wqe->sqe.num_sge != 1)
+		return -1;
+
+	if (bytes == 0)
+		return 0;
+
+	if (tx_flags(wqe) & SIW_WQE_INLINE)
+		memcpy(payload, &wqe->sqe.sge[1], bytes);
+	else {
+		struct siw_mr *mr = siw_mem2mr(wqe->mem[0].obj);
+
+		if (!mr->mem_obj) /* Kernel client using kva */
+			memcpy(payload, (void *)sge->laddr, bytes);
+		else if (c_tx->in_syscall) {
+			if (copy_from_user(payload,
+					   (void *)sge->laddr,
+					   bytes)) {
+				WARN_ON(1);
+				return -1;
+			}
+		} else {
+			unsigned int off = sge->laddr & ~PAGE_MASK;
+			struct page *p;
+			char *buffer;
+			int pbl_idx = 0;
+
+			if (!mr->mem.is_pbl)
+				p = siw_get_upage(mr->umem, sge->laddr);
+			else
+				p = siw_get_pblpage(mr, sge->laddr, &pbl_idx);
+
+			BUG_ON(!p);
+
+			buffer = kmap_atomic(p);
+
+			if (likely(PAGE_SIZE - off >= bytes)) {
+				memcpy(payload, buffer + off, bytes);
+				kunmap_atomic(buffer);
+			} else {
+				unsigned long part = bytes - (PAGE_SIZE - off);
+
+				memcpy(payload, buffer + off, part);
+				kunmap_atomic(buffer);
+				payload += part;
+
+				if (!mr->mem.is_pbl)
+					p = siw_get_upage(mr->umem,
+							  sge->laddr + part);
+				else
+					p = siw_get_pblpage(mr,
+							    sge->laddr + part,
+							    &pbl_idx);
+				BUG_ON(!p);
+
+				buffer = kmap_atomic(p);
+				memcpy(payload, buffer, bytes - part);
+				kunmap_atomic(buffer);
+			}
+		}
+	}
+	return (int)bytes;
+}
+
+#define PKT_FRAGMENTED 1
+#define PKT_COMPLETE 0
+
+/*
+ * siw_qp_prepare_tx()
+ *
+ * Prepare tx state for sending out one fpdu. Builds complete pkt
+ * if no user data or only immediate data are present.
+ *
+ * returns PKT_COMPLETE if complete pkt built, PKT_FRAGMENTED otherwise.
+ */
+static int siw_qp_prepare_tx(struct siw_iwarp_tx *c_tx)
+{
+	struct siw_wqe		*wqe = &c_tx->wqe_active;
+	char			*crc = NULL;
+	int			data = 0;
+
+	switch (tx_type(wqe)) {
+
+	case SIW_OP_READ:
+	case SIW_OP_READ_LOCAL_INV:
+		memcpy(&c_tx->pkt.ctrl,
+		       &iwarp_pktinfo[RDMAP_RDMA_READ_REQ].ctrl,
+		       sizeof(struct iwarp_ctrl));
+
+		c_tx->pkt.rreq.rsvd = 0;
+		c_tx->pkt.rreq.ddp_qn = htonl(RDMAP_UNTAGGED_QN_RDMA_READ);
+		c_tx->pkt.rreq.ddp_msn =
+			htonl(++c_tx->ddp_msn[RDMAP_UNTAGGED_QN_RDMA_READ]);
+		c_tx->pkt.rreq.ddp_mo = 0;
+		c_tx->pkt.rreq.sink_stag = htonl(wqe->sqe.sge[0].lkey);
+		c_tx->pkt.rreq.sink_to =
+			cpu_to_be64(wqe->sqe.sge[0].laddr); /* abs addr! */
+		c_tx->pkt.rreq.source_stag = htonl(wqe->sqe.rkey);
+		c_tx->pkt.rreq.source_to = cpu_to_be64(wqe->sqe.raddr);
+		c_tx->pkt.rreq.read_size = htonl(wqe->sqe.sge[0].length);
+
+		c_tx->ctrl_len = sizeof(struct iwarp_rdma_rreq);
+		crc = (char *)&c_tx->pkt.rreq_pkt.crc;
+		break;
+
+	case SIW_OP_SEND:
+		if (tx_flags(wqe) & SIW_WQE_SOLICITED)
+			memcpy(&c_tx->pkt.ctrl,
+			       &iwarp_pktinfo[RDMAP_SEND_SE].ctrl,
+			       sizeof(struct iwarp_ctrl));
+		else
+			memcpy(&c_tx->pkt.ctrl,
+			       &iwarp_pktinfo[RDMAP_SEND].ctrl,
+			       sizeof(struct iwarp_ctrl));
+
+		c_tx->pkt.send.ddp_qn = RDMAP_UNTAGGED_QN_SEND;
+		c_tx->pkt.send.ddp_msn =
+			htonl(++c_tx->ddp_msn[RDMAP_UNTAGGED_QN_SEND]);
+		c_tx->pkt.send.ddp_mo = 0;
+
+		c_tx->pkt.send_inv.inval_stag = 0;
+
+		c_tx->ctrl_len = sizeof(struct iwarp_send);
+
+		crc = (char *)&c_tx->pkt.send_pkt.crc;
+		data = siw_try_1seg(c_tx, crc);
+		break;
+
+	case SIW_OP_SEND_REMOTE_INV:
+		if (tx_flags(wqe) & SIW_WQE_SOLICITED)
+			memcpy(&c_tx->pkt.ctrl,
+			       &iwarp_pktinfo[RDMAP_SEND_SE_INVAL].ctrl,
+			       sizeof(struct iwarp_ctrl));
+		else
+			memcpy(&c_tx->pkt.ctrl,
+			       &iwarp_pktinfo[RDMAP_SEND_INVAL].ctrl,
+			       sizeof(struct iwarp_ctrl));
+
+		c_tx->pkt.send.ddp_qn = RDMAP_UNTAGGED_QN_SEND;
+		c_tx->pkt.send.ddp_msn =
+			htonl(++c_tx->ddp_msn[RDMAP_UNTAGGED_QN_SEND]);
+		c_tx->pkt.send.ddp_mo = 0;
+
+		c_tx->pkt.send_inv.inval_stag = cpu_to_be32(wqe->sqe.rkey);
+
+		c_tx->ctrl_len = sizeof(struct iwarp_send_inv);
+
+		crc = (char *)&c_tx->pkt.send_pkt.crc;
+		data = siw_try_1seg(c_tx, crc);
+		break;
+
+	case SIW_OP_WRITE:
+		memcpy(&c_tx->pkt.ctrl, &iwarp_pktinfo[RDMAP_RDMA_WRITE].ctrl,
+		       sizeof(struct iwarp_ctrl));
+
+		c_tx->pkt.rwrite.sink_stag = htonl(wqe->sqe.rkey);
+		c_tx->pkt.rwrite.sink_to = cpu_to_be64(wqe->sqe.raddr);
+		c_tx->ctrl_len = sizeof(struct iwarp_rdma_write);
+
+		crc = (char *)&c_tx->pkt.write_pkt.crc;
+		data = siw_try_1seg(c_tx, crc);
+		break;
+
+	case SIW_OP_READ_RESPONSE:
+		memcpy(&c_tx->pkt.ctrl,
+		       &iwarp_pktinfo[RDMAP_RDMA_READ_RESP].ctrl,
+		       sizeof(struct iwarp_ctrl));
+
+		/* NBO */
+		c_tx->pkt.rresp.sink_stag = cpu_to_be32(wqe->sqe.rkey);
+		c_tx->pkt.rresp.sink_to = cpu_to_be64(wqe->sqe.raddr);
+
+		c_tx->ctrl_len = sizeof(struct iwarp_rdma_rresp);
+
+		crc = (char *)&c_tx->pkt.write_pkt.crc;
+		data = siw_try_1seg(c_tx, crc);
+		break;
+
+	default:
+		dprint(DBG_ON, "Unsupported WQE type %d\n", tx_type(wqe));
+		BUG();
+		break;
+	}
+	c_tx->ctrl_sent = 0;
+
+	if (data >= 0) {
+		if (data > 0) {
+			wqe->processed = data;
+
+			c_tx->pkt.ctrl.mpa_len =
+				htons(c_tx->ctrl_len + data - MPA_HDR_SIZE);
+
+			/* compute eventual pad */
+			data += -(int)data & 0x3;
+			/* point CRC after data or pad */
+			crc += data;
+			c_tx->ctrl_len += data;
+
+			if (!(c_tx->pkt.ctrl.ddp_rdmap_ctrl & DDP_FLAG_TAGGED))
+				c_tx->pkt.c_untagged.ddp_mo = 0;
+			else
+				c_tx->pkt.c_tagged.ddp_to =
+				    cpu_to_be64(wqe->sqe.raddr);
+		}
+
+		*(u32 *)crc = 0;
+		/*
+		 * Do complete CRC if enabled and short packet
+		 */
+		if (c_tx->mpa_crc_hd) {
+			if (siw_crc_txhdr(c_tx) != 0)
+				return -EINVAL;
+			crypto_shash_final(c_tx->mpa_crc_hd, (u8 *)crc);
+		}
+		c_tx->ctrl_len += MPA_CRC_SIZE;
+
+		return PKT_COMPLETE;
+	}
+	c_tx->ctrl_len += MPA_CRC_SIZE;
+	c_tx->sge_idx = 0;
+	c_tx->sge_off = 0;
+	c_tx->pbl_idx = 0;
+
+	/*
+	 * Allow direct sending out of user buffer if WR is non signalled
+	 * and payload is over threshold and no CRC is enabled.
+	 * Per RDMA verbs, the application should not change the send buffer
+	 * until the work completed. In iWarp, work completion is only
+	 * local delivery to TCP. TCP may reuse the buffer for
+	 * retransmission. Changing unsent data also breaks the CRC,
+	 * if applied.
+	 */
+	if (zcopy_tx
+	    && wqe->bytes > SENDPAGE_THRESH
+	    && !(tx_flags(wqe) & SIW_WQE_SIGNALLED)
+	    && tx_type(wqe) != SIW_OP_READ
+	    && tx_type(wqe) != SIW_OP_READ_LOCAL_INV)
+		c_tx->use_sendpage = 1;
+	else
+		c_tx->use_sendpage = 0;
+
+	return PKT_FRAGMENTED;
+}
+
+/*
+ * Send out one complete control type FPDU, or header of FPDU carrying
+ * data. Used for fixed sized packets like Read.Requests or zero length
+ * SENDs, WRITEs, READ.Responses, or header only.
+ */
+static inline int siw_tx_ctrl(struct siw_iwarp_tx *c_tx, struct socket *s,
+			      int flags)
+{
+	struct msghdr msg = {.msg_flags = flags};
+	struct kvec iov = {
+		.iov_base = (char *)&c_tx->pkt.ctrl + c_tx->ctrl_sent,
+		.iov_len = c_tx->ctrl_len - c_tx->ctrl_sent};
+
+	int rv = kernel_sendmsg(s, &msg, &iov, 1,
+				c_tx->ctrl_len - c_tx->ctrl_sent);
+
+	dprint(DBG_TX, " (QP%d): op=%d, %d of %d sent (%d)\n",
+		TX_QPID(c_tx), __rdmap_opcode(&c_tx->pkt.ctrl),
+		c_tx->ctrl_sent + rv, c_tx->ctrl_len, rv);
+
+	if (rv >= 0) {
+		c_tx->ctrl_sent += rv;
+
+		if (c_tx->ctrl_sent == c_tx->ctrl_len) {
+			siw_dprint_hdr(&c_tx->pkt.hdr, TX_QPID(c_tx),
+					"HDR/CTRL sent");
+			rv = 0;
+		} else if (c_tx->ctrl_sent < c_tx->ctrl_len)
+			rv = -EAGAIN;
+		else
+			BUG();
+	}
+	return rv;
+}
+
+/*
+ * 0copy TCP transmit interface:  Push page array page by page,
+ * or use do_tcp_sendpages, if exported.
+ *
+ * Using sendpage to push page by page appears to be less efficient
+ * than using sendmsg, even if data are copied.
+ *
+ * A general performance limitation might be the extra four bytes
+ * trailer checksum segment to be pushed after user data.
+ */
+static int siw_tcp_sendpages(struct socket *s, struct page **page,
+			     int offset, size_t size)
+{
+	struct sock *sk = s->sk;
+	int i = 0, rv = 0, sent = 0,
+	    flags = MSG_MORE|MSG_DONTWAIT|MSG_SENDPAGE_NOTLAST;
+
+	while (size) {
+		size_t bytes = min_t(size_t, PAGE_SIZE - offset, size);
+
+		if (size + offset <= PAGE_SIZE)
+			flags = MSG_MORE|MSG_DONTWAIT;
+
+		tcp_rate_check_app_limited(sk);
+try_page_again:
+		lock_sock(sk);
+		rv = do_tcp_sendpages(sk, page[i], offset, bytes, flags);
+		release_sock(sk);
+
+		if (rv > 0) {
+			size -= rv;
+			sent += rv;
+			if (rv != bytes) {
+				offset += rv;
+				bytes -= rv;
+				goto try_page_again;
+			}
+			offset = 0;
+		} else {
+			if (rv == -EAGAIN || rv == 0)
+				break;
+			return rv;
+		}
+		i++;
+	}
+	return sent;
+}
+
+/*
+ * siw_0copy_tx()
+ *
+ * Pushes list of pages to TCP socket. If pages from multiple
+ * SGE's, all referenced pages of each SGE are pushed in one
+ * shot.
+ */
+static int siw_0copy_tx(struct socket *s, struct page **page,
+			struct siw_sge *sge, unsigned int offset,
+			unsigned int size)
+{
+	int i = 0, sent = 0, rv;
+	int sge_bytes = min(sge->length - offset, size);
+
+	offset  = (sge->laddr + offset) & ~PAGE_MASK;
+
+	while (sent != size) {
+
+		rv = siw_tcp_sendpages(s, &page[i], offset, sge_bytes);
+		if (rv >= 0) {
+			sent += rv;
+			if (size == sent || sge_bytes > rv)
+				break;
+
+			i += PAGE_ALIGN(sge_bytes + offset) >> PAGE_SHIFT;
+			sge++;
+			sge_bytes = min(sge->length, size - sent);
+			offset = sge->laddr & ~PAGE_MASK;
+		} else {
+			sent = rv;
+			break;
+		}
+	}
+	return sent;
+}
+
+#define MAX_TRAILER (MPA_CRC_SIZE + 4)
+
+/*
+ * siw_tx_hdt() tries to push a complete packet to TCP where all
+ * packet fragments are referenced by the elements of one iovec.
+ * For the data portion, each involved page must be referenced by
+ * one extra element. All sge's data can be non-aligned to page
+ * boundaries. Two more elements are referencing iWARP header
+ * and trailer:
+ * MAX_ARRAY = 64KB/PAGE_SIZE + 1 + (2 * (SIW_MAX_SGE - 1) + HDR + TRL
+ */
+#define MAX_ARRAY ((0xffff / PAGE_SIZE) + 1 + (2 * (SIW_MAX_SGE - 1) + 2))
+
+/*
+ * Write out iov referencing hdr, data and trailer of current FPDU.
+ * Update transmit state dependent on write return status
+ */
+static int siw_tx_hdt(struct siw_iwarp_tx *c_tx, struct socket *s)
+{
+	struct siw_wqe		*wqe = &c_tx->wqe_active;
+	struct siw_sge		*sge = &wqe->sqe.sge[c_tx->sge_idx],
+				*first_sge = sge;
+	union siw_mem_resolved	*mem = &wqe->mem[c_tx->sge_idx];
+	struct siw_mr		*mr = NULL;
+
+	struct kvec		iov[MAX_ARRAY];
+	struct page		*page_array[MAX_ARRAY];
+	struct msghdr		msg = {.msg_flags = MSG_DONTWAIT|MSG_EOR};
+
+	int			seg = 0, do_crc = c_tx->do_crc, is_kva = 0, rv;
+	unsigned int		data_len = c_tx->bytes_unsent,
+				hdr_len = 0,
+				trl_len = 0,
+				sge_off = c_tx->sge_off,
+				sge_idx = c_tx->sge_idx,
+				pbl_idx = c_tx->pbl_idx;
+
+	if (c_tx->state == SIW_SEND_HDR) {
+		if (c_tx->use_sendpage) {
+			rv = siw_tx_ctrl(c_tx, s, MSG_DONTWAIT|MSG_MORE);
+			if (rv)
+				goto done;
+
+			c_tx->state = SIW_SEND_DATA;
+		} else {
+			iov[0].iov_base =
+				(char *)&c_tx->pkt.ctrl + c_tx->ctrl_sent;
+			iov[0].iov_len = hdr_len =
+				c_tx->ctrl_len - c_tx->ctrl_sent;
+			seg = 1;
+			siw_dprint_hdr(&c_tx->pkt.hdr, TX_QPID(c_tx),
+					"HDR to send");
+		}
+	}
+
+	wqe->processed += data_len;
+
+	while (data_len) { /* walk the list of SGE's */
+		unsigned int	sge_len = min(sge->length - sge_off, data_len);
+		unsigned int	fp_off = (sge->laddr + sge_off) & ~PAGE_MASK;
+
+		BUG_ON(!sge_len);
+
+		if (!(tx_flags(wqe) & SIW_WQE_INLINE)) {
+			mr = siw_mem2mr(mem->obj);
+			if (!mr->mem_obj)
+				is_kva = 1;
+		} else
+			is_kva = 1;
+
+		if (is_kva && !c_tx->use_sendpage) {
+			/*
+			 * tx from kernel virtual address: either inline data
+			 * or memory region with assigned kernel buffer
+			 */
+			iov[seg].iov_base = (void *)(sge->laddr + sge_off);
+			iov[seg].iov_len = sge_len;
+
+			if (do_crc)
+				siw_crc_array(c_tx->mpa_crc_hd,
+					      iov[seg].iov_base, sge_len);
+			sge_off += sge_len;
+			data_len -= sge_len;
+			seg++;
+			goto sge_done;
+		}
+
+		while (sge_len) {
+			size_t plen = min((int)PAGE_SIZE - fp_off, sge_len);
+
+			BUG_ON(plen <= 0);
+			if (!is_kva) {
+				struct page *p;
+
+				if (mr->mem.is_pbl)
+					p = siw_get_pblpage(mr,
+						sge->laddr + sge_off,
+						&pbl_idx);
+				else
+					p = siw_get_upage(mr->umem, sge->laddr
+							  + sge_off);
+				BUG_ON(!p);
+				page_array[seg] = p;
+
+				if (!c_tx->use_sendpage) {
+					iov[seg].iov_base = kmap(p) + fp_off;
+					iov[seg].iov_len = plen;
+				}
+				if (do_crc)
+					siw_crc_page(c_tx->mpa_crc_hd, p,
+						     fp_off, plen);
+			} else {
+				u64 pa = ((sge->laddr + sge_off) & PAGE_MASK);
+
+				page_array[seg] = virt_to_page(pa);
+				if (do_crc)
+					siw_crc_array(c_tx->mpa_crc_hd,
+						(void *)(sge->laddr + sge_off),
+						plen);
+			}
+
+			sge_len -= plen;
+			sge_off += plen;
+			data_len -= plen;
+			fp_off = 0;
+
+			if (++seg > (int)MAX_ARRAY) {
+				dprint(DBG_ON, "(QP%d): Too many fragments\n",
+				       TX_QPID(c_tx));
+				if (!is_kva && !c_tx->use_sendpage) {
+					int i = (hdr_len > 0) ? 1 : 0;
+
+					seg--;
+					while (i < seg)
+						kunmap(page_array[i++]);
+				}
+				wqe->processed -= c_tx->bytes_unsent;
+				rv = -EMSGSIZE;
+				goto done_crc;
+			}
+		}
+sge_done:
+		/* Update SGE variables at end of SGE */
+		if (sge_off == sge->length &&
+		    (data_len != 0 || wqe->processed < wqe->bytes)) {
+			sge_idx++;
+			sge++;
+			mem++;
+			sge_off = 0;
+		}
+	}
+	/* trailer */
+	if (likely(c_tx->state != SIW_SEND_TRAILER)) {
+		iov[seg].iov_base = &c_tx->trailer.pad[4 - c_tx->pad];
+		iov[seg].iov_len = trl_len = MAX_TRAILER - (4 - c_tx->pad);
+	} else {
+		iov[seg].iov_base = &c_tx->trailer.pad[c_tx->ctrl_sent];
+		iov[seg].iov_len = trl_len = MAX_TRAILER - c_tx->ctrl_sent;
+	}
+
+	if (c_tx->pad) {
+		*(u32 *)c_tx->trailer.pad = 0;
+		if (do_crc)
+			siw_crc_array(c_tx->mpa_crc_hd,
+				      (u8 *)&c_tx->trailer.crc - c_tx->pad,
+				      c_tx->pad);
+	}
+	if (!c_tx->mpa_crc_hd)
+		c_tx->trailer.crc = 0;
+	else if (do_crc)
+		crypto_shash_final(c_tx->mpa_crc_hd,
+				   (u8 *)&c_tx->trailer.crc);
+
+	data_len = c_tx->bytes_unsent;
+
+	if (c_tx->use_sendpage) {
+		rv = siw_0copy_tx(s, page_array, first_sge, c_tx->sge_off,
+				  data_len);
+		if (rv == data_len) {
+			rv = kernel_sendmsg(s, &msg, &iov[seg], 1, trl_len);
+			if (rv > 0)
+				rv += data_len;
+			else
+				rv = data_len;
+		}
+	} else {
+		rv = kernel_sendmsg(s, &msg, iov, seg + 1,
+				    hdr_len + data_len + trl_len);
+		if (!is_kva) {
+			int i = (hdr_len > 0) ? 1 : 0;
+
+			while (i < seg)
+				kunmap(page_array[i++]);
+		}
+		dprint(DBG_HDR, " QP[%d]: sendmsg rv = %d\n", TX_QPID(c_tx),
+			rv);
+	}
+	if (rv < (int)hdr_len) {
+		/* Not even complete hdr pushed or negative rv */
+		wqe->processed -= data_len;
+		if (rv >= 0) {
+			c_tx->ctrl_sent += rv;
+			rv = -EAGAIN;
+		}
+		goto done_crc;
+	}
+
+	rv -= hdr_len;
+
+	if (rv >= (int)data_len) {
+		/* all user data pushed to TCP or no data to push */
+		if (data_len > 0 && wqe->processed < wqe->bytes) {
+			/* Save the current state for next tx */
+			c_tx->sge_idx = sge_idx;
+			c_tx->sge_off = sge_off;
+			c_tx->pbl_idx = pbl_idx;
+		}
+		rv -= data_len;
+
+		if (rv == trl_len) /* all pushed */
+			rv = 0;
+		else {
+			c_tx->state = SIW_SEND_TRAILER;
+			c_tx->ctrl_len = MAX_TRAILER;
+			c_tx->ctrl_sent = rv + 4 - c_tx->pad;
+			c_tx->bytes_unsent = 0;
+			rv = -EAGAIN;
+		}
+
+	} else if (data_len > 0) {
+		/* Maybe some user data pushed to TCP */
+		c_tx->state = SIW_SEND_DATA;
+		wqe->processed -= data_len - rv;
+
+		if (rv) {
+			/*
+			 * Some bytes out. Recompute tx state based
+			 * on old state and bytes pushed
+			 */
+			unsigned int sge_unsent;
+
+			c_tx->bytes_unsent -= rv;
+			sge = &wqe->sqe.sge[c_tx->sge_idx];
+			sge_unsent = sge->length - c_tx->sge_off;
+
+			while (sge_unsent <= rv) {
+				rv -= sge_unsent;
+				c_tx->sge_idx++;
+				c_tx->sge_off = 0;
+				sge++;
+				sge_unsent = sge->length;
+			}
+			c_tx->sge_off += rv;
+			BUG_ON(c_tx->sge_off >= sge->length);
+		}
+		rv = -EAGAIN;
+	}
+done_crc:
+	c_tx->do_crc = 0;
+done:
+	return rv;
+}
+
+static void siw_update_tcpseg(struct siw_iwarp_tx *c_tx, struct socket *s)
+{
+	struct tcp_sock *tp = tcp_sk(s->sk);
+
+	if (tp->gso_segs) {
+		if (gso_seg_limit == 0)
+			c_tx->tcp_seglen =
+				tp->mss_cache * tp->gso_segs;
+		else
+			c_tx->tcp_seglen = tp->mss_cache *
+				min_t(unsigned int, gso_seg_limit,
+				      tp->gso_segs);
+	} else
+		c_tx->tcp_seglen = tp->mss_cache;
+}
+
+/*
+ * siw_unseg_txlen()
+ *
+ * Compute complete tcp payload len if packet would not
+ * get fragmented
+ */
+static inline int siw_unseg_txlen(struct siw_iwarp_tx *c_tx)
+{
+	int pad = c_tx->bytes_unsent ? -c_tx->bytes_unsent & 0x3 : 0;
+
+	return c_tx->bytes_unsent + c_tx->ctrl_len + pad + MPA_CRC_SIZE;
+}
+
+
+/*
+ * siw_prepare_fpdu()
+ *
+ * Prepares transmit context to send out one FPDU if FPDU will contain
+ * user data and user data are not immediate data.
+ * Computes maximum FPDU length to fill up TCP MSS if possible.
+ *
+ * @qp:		QP from which to transmit
+ * @wqe:	Current WQE causing transmission
+ *
+ * TODO: Take into account real available sendspace on socket
+ *       to avoid header misalignment due to send pausing within
+ *       fpdu transmission
+ */
+static void siw_prepare_fpdu(struct siw_qp *qp, struct siw_wqe *wqe)
+{
+	struct siw_iwarp_tx	*c_tx  = &qp->tx_ctx;
+	int data_len;
+
+	c_tx->ctrl_len = iwarp_pktinfo[__rdmap_opcode(&c_tx->pkt.ctrl)].hdr_len;
+	c_tx->ctrl_sent = 0;
+
+	/*
+	 * Update target buffer offset if any
+	 */
+	if (!(c_tx->pkt.ctrl.ddp_rdmap_ctrl & DDP_FLAG_TAGGED))
+		/* Untagged message */
+		c_tx->pkt.c_untagged.ddp_mo = cpu_to_be32(wqe->processed);
+	else	/* Tagged message */
+		c_tx->pkt.c_tagged.ddp_to =
+		    cpu_to_be64(wqe->sqe.raddr + wqe->processed);
+
+	data_len = wqe->bytes - wqe->processed;
+	if (data_len + c_tx->ctrl_len + MPA_CRC_SIZE > c_tx->tcp_seglen) {
+		/* Trim DDP payload to fit into current TCP segment */
+		data_len = c_tx->tcp_seglen - (c_tx->ctrl_len + MPA_CRC_SIZE);
+		c_tx->pkt.ctrl.ddp_rdmap_ctrl &= ~DDP_FLAG_LAST;
+		c_tx->pad = 0;
+	} else {
+		c_tx->pkt.ctrl.ddp_rdmap_ctrl |= DDP_FLAG_LAST;
+		c_tx->pad = -data_len & 0x3;
+	}
+	c_tx->bytes_unsent = data_len;
+
+	c_tx->pkt.ctrl.mpa_len =
+		htons(c_tx->ctrl_len + data_len - MPA_HDR_SIZE);
+
+	/*
+	 * Init MPA CRC computation
+	 */
+	if (c_tx->mpa_crc_hd) {
+		siw_crc_txhdr(c_tx);
+		c_tx->do_crc = 1;
+	}
+}
+
+/*
+ * siw_check_sgl_tx()
+ *
+ * Check permissions for a list of SGE's (SGL).
+ * A successful check will have all memory referenced
+ * for transmission resolved and assigned to the WQE.
+ *
+ * @pd:		Protection Domain SGL should belong to
+ * @wqe:	WQE to be checked
+ * @perms:	requested access permissions
+ *
+ */
+
+int siw_check_sgl_tx(struct siw_pd *pd, struct siw_wqe *wqe,
+		     enum siw_access_flags perms)
+{
+	struct siw_sge		*sge = &wqe->sqe.sge[0];
+	union siw_mem_resolved	*mem = &wqe->mem[0];
+	int	num_sge = wqe->sqe.num_sge,
+		len = 0;
+
+	dprint(DBG_WR, "(PD%d): Enter\n", OBJ_ID(pd));
+
+	if (unlikely(num_sge > SIW_MAX_SGE))
+		return -EINVAL;
+
+	while (num_sge-- > 0) {
+		dprint(DBG_WR, "(PD%d): perms=0x%x, len=%d, sge->len=%d\n",
+			OBJ_ID(pd), perms, len, sge->length);
+		/*
+		 * rdma verbs: do not check stag for a zero length sge
+		 */
+		if (sge->length &&
+		    siw_check_sge(pd, sge, mem, perms, 0, sge->length) != 0) {
+			len = -EINVAL;
+			break;
+		}
+		len += sge->length;
+		sge++;
+		mem++;
+	}
+	return len;
+}
+
+/*
+ * siw_qp_sq_proc_tx()
+ *
+ * Process one WQE which needs transmission on the wire.
+ */
+static int siw_qp_sq_proc_tx(struct siw_qp *qp, struct siw_wqe *wqe)
+{
+	struct siw_iwarp_tx	*c_tx = &qp->tx_ctx;
+	struct socket		*s = qp->attrs.llp_stream_handle;
+	int			rv = 0,
+				burst_len = qp->tx_ctx.burst;
+
+	if (unlikely(wqe->wr_status == SIW_WR_IDLE))
+		return 0;
+
+	if (!burst_len)
+		burst_len = SQ_USER_MAXBURST;
+
+	if (wqe->wr_status == SIW_WR_QUEUED) {
+		if (!(wqe->sqe.flags & SIW_WQE_INLINE)) {
+			if (tx_type(wqe) == SIW_OP_READ_RESPONSE)
+				wqe->sqe.num_sge = 1;
+
+			if (tx_type(wqe) != SIW_OP_READ &&
+			    tx_type(wqe) != SIW_OP_READ_LOCAL_INV) {
+				/*
+				 * Reference memory to be tx'd
+				 */
+				rv = siw_check_sgl_tx(qp->pd, wqe,
+						      SIW_MEM_LREAD);
+				if (rv < 0)
+					goto tx_done;
+
+				wqe->bytes = rv;
+			} else
+				wqe->bytes = 0;
+		} else {
+			wqe->bytes = wqe->sqe.sge[0].length;
+			if (!qp->kernel_verbs) {
+				if (wqe->bytes > SIW_MAX_INLINE)
+					return -EINVAL;
+				wqe->sqe.sge[0].laddr = (u64)&wqe->sqe.sge[1];
+			}
+		}
+		wqe->wr_status = SIW_WR_INPROGRESS;
+		wqe->processed = 0;
+
+		siw_update_tcpseg(c_tx, s);
+
+		rv = siw_qp_prepare_tx(c_tx);
+		if (rv == PKT_FRAGMENTED) {
+			c_tx->state = SIW_SEND_HDR;
+			siw_prepare_fpdu(qp, wqe);
+		} else if (rv == PKT_COMPLETE)
+			c_tx->state = SIW_SEND_SHORT_FPDU;
+		else
+			goto tx_done;
+	}
+
+next_segment:
+	dprint(DBG_WR|DBG_TX,
+		" QP(%d): WR type %d, state %d, data %u, sent %u, id %llx\n",
+		QP_ID(qp), tx_type(wqe), wqe->wr_status, wqe->bytes,
+		wqe->processed, wqe->sqe.id);
+
+	if (--burst_len == 0) {
+		rv = -EINPROGRESS;
+		goto tx_done;
+	}
+	if (c_tx->state == SIW_SEND_SHORT_FPDU) {
+		enum siw_opcode tx_type = tx_type(wqe);
+
+		/*
+		 * Always end current TCP segment (no MSG_MORE flag):
+		 * trying to fill segment would result in excessive delay.
+		 */
+		rv = siw_tx_ctrl(c_tx, s, MSG_DONTWAIT);
+
+		if (!rv && tx_type != SIW_OP_READ &&
+		    tx_type != SIW_OP_READ_LOCAL_INV)
+			wqe->processed = wqe->bytes;
+
+		goto tx_done;
+
+	} else
+		rv = siw_tx_hdt(c_tx, s);
+
+	if (!rv) {
+		/*
+		 * One segment sent. Processing completed if last
+		 * segment, Do next segment otherwise.
+		 */
+		if (unlikely(c_tx->tx_suspend)) {
+			/*
+			 * Verbs, 6.4.: Try stopping sending after a full
+			 * DDP segment if the connection goes down
+			 * (== peer halfclose)
+			 */
+			rv = -ECONNABORTED;
+			goto tx_done;
+		}
+		if (c_tx->pkt.ctrl.ddp_rdmap_ctrl & DDP_FLAG_LAST) {
+			dprint(DBG_TX, "(QP%d): WR completed\n", QP_ID(qp));
+			goto tx_done;
+		}
+		c_tx->state = SIW_SEND_HDR;
+
+		siw_update_tcpseg(c_tx, s);
+
+		siw_prepare_fpdu(qp, wqe);
+		goto next_segment;
+	}
+tx_done:
+	qp->tx_ctx.burst = burst_len;
+	return rv;
+}
+
+static int siw_fastreg_mr(struct siw_pd *pd, struct siw_sqe *sqe)
+{
+	struct siw_mem *mem = siw_mem_id2obj(pd->hdr.sdev, sqe->rkey >> 8);
+	struct siw_mr *mr;
+	int rv = 0;
+
+	dprint(DBG_MM, ": STag %u (%x) Enter\n", sqe->rkey >> 8, sqe->rkey);
+
+	if (!mem) {
+		dprint(DBG_ON, ": STag %u unknown\n", sqe->rkey >> 8);
+		return -EINVAL;
+	}
+	mr = siw_mem2mr(mem);
+	if (&mr->ofa_mr != (void *)sqe->ofa_mr) {
+		dprint(DBG_ON, ": STag %u: unexpected MR\n", sqe->rkey >> 8);
+		rv = -EINVAL;
+		goto out;
+	}
+	if (mr->pd != pd) {
+		dprint(DBG_ON, ": PD mismatch: %p != %p\n", mr->pd, pd);
+		rv = -EINVAL;
+		goto out;
+	}
+	if (mem->stag_valid) {
+		dprint(DBG_ON, ": STag already valid: %u\n",
+			sqe->rkey >> 8);
+		rv = -EINVAL;
+		goto out;
+	}
+	mem->perms = sqe->access;
+	mem->stag_valid = 1;
+	dprint(DBG_MM, ": STag now valid: %u\n", sqe->rkey >> 8);
+out:
+	siw_mem_put(mem);
+	return rv;
+}
+
+static int siw_qp_sq_proc_local(struct siw_qp *qp, struct siw_wqe *wqe)
+{
+	int rv;
+
+	switch (tx_type(wqe)) {
+
+	case SIW_OP_REG_MR:
+		rv = siw_fastreg_mr(qp->pd, &wqe->sqe);
+		break;
+
+	case SIW_OP_INVAL_STAG:
+		rv = siw_invalidate_stag(qp->pd, wqe->sqe.rkey);
+		break;
+
+	default:
+		rv = -EINVAL;
+	}
+	return rv;
+}
+
+
+/*
+ * siw_qp_sq_process()
+ *
+ * Core TX path routine for RDMAP/DDP/MPA using a TCP kernel socket.
+ * Sends RDMAP payload for the current SQ WR @wqe of @qp in one or more
+ * MPA FPDUs, each containing a DDP segment.
+ *
+ * SQ processing may occur in user context as a result of posting
+ * new WQE's or from siw_sq_work_handler() context. Processing in
+ * user context is limited to non-kernel verbs users.
+ *
+ * SQ processing may get paused anytime, possibly in the middle of a WR
+ * or FPDU, if insufficient send space is available. SQ processing
+ * gets resumed from siw_sq_work_handler(), if send space becomes
+ * available again.
+ *
+ * Must be called with the QP state read-locked.
+ *
+ * TODO:
+ * To be solved more seriously: an outbound RREQ can be satisfied
+ * by the corresponding RRESP _before_ it gets assigned to the ORQ.
+ * This happens regularly in RDMA READ via loopback case. Since both
+ * outbound RREQ and inbound RRESP can be handled by the same CPU
+ * locking the ORQ is dead-lock prone and thus not an option.
+ * Tentatively, the RREQ gets assigned to the ORQ _before_ being
+ * sent (and pulled back in case of send failure).
+ */
+int siw_qp_sq_process(struct siw_qp *qp)
+{
+	struct siw_wqe		*wqe = tx_wqe(qp);
+	enum siw_opcode		tx_type;
+	unsigned long		flags;
+	int			rv = 0;
+
+	wait_event(qp->tx_ctx.waitq, !atomic_read(&qp->tx_ctx.in_use));
+
+	if (atomic_inc_return(&qp->tx_ctx.in_use) > 1) {
+		pr_warn("SIW: QP[%d] already active\n", QP_ID(qp));
+		goto done;
+	}
+next_wqe:
+	/*
+	 * Stop QP processing if SQ state changed
+	 */
+	if (unlikely(qp->tx_ctx.tx_suspend)) {
+		dprint(DBG_WR|DBG_TX, "(QP%d): tx suspend\n", QP_ID(qp));
+		goto done;
+	}
+	tx_type = tx_type(wqe);
+
+	if (tx_type <= SIW_OP_READ_RESPONSE)
+		rv = siw_qp_sq_proc_tx(qp, wqe);
+	else
+		rv = siw_qp_sq_proc_local(qp, wqe);
+
+	if (!rv) {
+		/*
+		 * WQE processing done
+		 */
+		switch (tx_type) {
+
+		case SIW_OP_SEND:
+		case SIW_OP_SEND_REMOTE_INV:
+		case SIW_OP_WRITE:
+			siw_wqe_put_mem(wqe, tx_type);
+		case SIW_OP_INVAL_STAG:
+		case SIW_OP_REG_MR:
+			if (tx_flags(wqe) & SIW_WQE_SIGNALLED)
+				siw_sqe_complete(qp, &wqe->sqe, wqe->bytes,
+						 SIW_WC_SUCCESS);
+			break;
+
+		case SIW_OP_READ:
+		case SIW_OP_READ_LOCAL_INV:
+			/*
+			 * already enqueued to ORQ queue
+			 */
+			break;
+
+		case SIW_OP_READ_RESPONSE:
+			siw_wqe_put_mem(wqe, tx_type);
+			break;
+
+		default:
+			BUG();
+		}
+
+		spin_lock_irqsave(&qp->sq_lock, flags);
+		wqe->wr_status = SIW_WR_IDLE;
+		rv = siw_activate_tx(qp);
+		spin_unlock_irqrestore(&qp->sq_lock, flags);
+
+		if (unlikely(rv <= 0))
+			goto done;
+
+		goto next_wqe;
+
+	} else if (rv == -EAGAIN) {
+		dprint(DBG_WR|DBG_TX,
+			"(QP%d): SQ paused: hd/tr %d of %d, data %d\n",
+			QP_ID(qp), qp->tx_ctx.ctrl_sent, qp->tx_ctx.ctrl_len,
+			qp->tx_ctx.bytes_unsent);
+		rv = 0;
+		goto done;
+	} else if (rv == -EINPROGRESS) {
+		siw_sq_start(qp);
+		rv = 0;
+		goto done;
+	} else {
+		/*
+		 * WQE processing failed.
+		 * Verbs 8.3.2:
+		 * o It turns any WQE into a signalled WQE.
+		 * o Local catastrophic error must be surfaced
+		 * o QP must be moved into Terminate state: done by code
+		 *   doing socket state change processing
+		 *
+		 * o TODO: Termination message must be sent.
+		 * o TODO: Implement more precise work completion errors,
+		 *         see enum ib_wc_status in ib_verbs.h
+		 */
+		dprint(DBG_ON, " (QP%d): WQE type %d processing failed: %d\n",
+				QP_ID(qp), tx_type(wqe), rv);
+
+		spin_lock_irqsave(&qp->sq_lock, flags);
+		/*
+		 * RREQ may have already been completed by inbound RRESP!
+		 */
+		if (tx_type == SIW_OP_READ ||
+		    tx_type == SIW_OP_READ_LOCAL_INV) {
+			/* Cleanup pending entry in ORQ */
+			qp->orq_put--;
+			qp->orq[qp->orq_put % qp->attrs.orq_size].flags = 0;
+		}
+		spin_unlock_irqrestore(&qp->sq_lock, flags);
+		/*
+		 * immediately suspends further TX processing
+		 */
+		if (!qp->tx_ctx.tx_suspend)
+			siw_qp_cm_drop(qp, 0);
+
+		switch (tx_type) {
+
+		case SIW_OP_SEND:
+		case SIW_OP_SEND_REMOTE_INV:
+		case SIW_OP_SEND_WITH_IMM:
+		case SIW_OP_WRITE:
+		case SIW_OP_READ:
+		case SIW_OP_READ_LOCAL_INV:
+			siw_wqe_put_mem(wqe, tx_type);
+		case SIW_OP_INVAL_STAG:
+		case SIW_OP_REG_MR:
+			siw_sqe_complete(qp, &wqe->sqe, wqe->bytes,
+					 SIW_WC_LOC_QP_OP_ERR);
+
+			siw_qp_event(qp, IB_EVENT_QP_FATAL);
+
+			break;
+
+		case SIW_OP_READ_RESPONSE:
+			dprint(DBG_WR|DBG_TX|DBG_ON,
+				"(QP%d): Processing RRESPONSE failed: %d\n",
+				QP_ID(qp), rv);
+
+			siw_qp_event(qp, IB_EVENT_QP_REQ_ERR);
+
+			siw_wqe_put_mem(wqe, SIW_OP_READ_RESPONSE);
+
+			break;
+
+		default:
+			BUG();
+		}
+		wqe->wr_status = SIW_WR_IDLE;
+	}
+done:
+	atomic_dec(&qp->tx_ctx.in_use);
+	wake_up(&qp->tx_ctx.waitq);
+
+	return rv;
+}
+
+static void siw_sq_resume(struct siw_qp *qp)
+{
+
+	if (down_read_trylock(&qp->state_lock)) {
+		if (likely(qp->attrs.state == SIW_QP_STATE_RTS &&
+			!qp->tx_ctx.tx_suspend)) {
+
+			int rv = siw_qp_sq_process(qp);
+
+			up_read(&qp->state_lock);
+
+			if (unlikely(rv < 0)) {
+				pr_info("QP[%d]: SQ task failed: %d\n",
+					QP_ID(qp), rv);
+				if (!qp->tx_ctx.tx_suspend)
+					siw_qp_cm_drop(qp, 0);
+			}
+		} else
+			up_read(&qp->state_lock);
+	} else
+		pr_info("QP[%d]: Resume SQ while QP locked\n", QP_ID(qp));
+
+	siw_qp_put(qp);
+}
+
+struct tx_task_t {
+	struct llist_head active;
+	wait_queue_head_t waiting;
+};
+
+DEFINE_PER_CPU(struct tx_task_t, tx_task_g);
+
+void siw_stop_tx_thread(int nr_cpu)
+{
+	kthread_stop(qp_tx_thread[nr_cpu]);
+	wake_up(&per_cpu(tx_task_g, nr_cpu).waiting);
+}
+
+int siw_run_sq(void *data)
+{
+	const int nr_cpu = (unsigned int)(long)data;
+	struct llist_node *active;
+	struct siw_qp *qp;
+	struct tx_task_t *tx_task = &per_cpu(tx_task_g, nr_cpu);
+
+	init_llist_head(&tx_task->active);
+	init_waitqueue_head(&tx_task->waiting);
+
+	pr_info("Started siw TX thread on CPU %u\n", nr_cpu);
+
+	while (1) {
+		struct llist_node *fifo_list = NULL;
+
+		wait_event_interruptible(tx_task->waiting,
+					 !llist_empty(&tx_task->active) ||
+					 kthread_should_stop());
+
+		if (kthread_should_stop())
+			break;
+
+		active = llist_del_all(&tx_task->active);
+		/*
+		 * llist_del_all returns a list with newest entry first.
+		 * Re-order list for fairness among QP's.
+		 */
+		while (active) {
+			struct llist_node *tmp = active;
+
+			active = llist_next(active);
+			tmp->next = fifo_list;
+			fifo_list = tmp;
+		}
+		while (fifo_list) {
+			qp = container_of(fifo_list, struct siw_qp, tx_list);
+			fifo_list = llist_next(fifo_list);
+			qp->tx_list.next = NULL;
+
+			siw_sq_resume(qp);
+		}
+	}
+	active = llist_del_all(&tx_task->active);
+	if (active != NULL) {
+		llist_for_each_entry(qp, active, tx_list) {
+			qp->tx_list.next = NULL;
+			siw_sq_resume(qp);
+		}
+	}
+	pr_info("Stopped siw TX thread on CPU %u\n", nr_cpu);
+	return 0;
+}
+
+int siw_sq_start(struct siw_qp *qp)
+{
+	int cpu = qp->cpu;
+
+	if (tx_wqe(qp)->wr_status == SIW_WR_IDLE)
+		goto out;
+
+	dprint(DBG_TX|DBG_OBJ, "(qp%d)\n", QP_ID(qp));
+
+	if (!cpu_online(cpu) || qp_tx_thread[cpu] == NULL)
+		cpu = default_tx_cpu;
+
+	if (unlikely(cpu < 0)) {
+		WARN_ON(1);
+		goto out;
+	}
+	if (!llist_empty(&per_cpu(tx_task_g, cpu).active)) {
+		int new_cpu;
+
+		for_each_online_cpu(new_cpu) {
+			if (qp_tx_thread[new_cpu] != NULL &&
+			    llist_empty(&per_cpu(tx_task_g, new_cpu).active)) {
+				cpu = new_cpu;
+				qp->cpu = new_cpu;
+				break;
+			}
+		}
+	}
+
+	siw_qp_get(qp);
+	llist_add(&qp->tx_list, &per_cpu(tx_task_g, cpu).active);
+
+	wake_up(&per_cpu(tx_task_g, cpu).waiting);
+out:
+	return 0;
+}
-- 
2.13.6

--
To unsubscribe from this list: send the line "unsubscribe linux-rdma" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html