1 // SPDX-License-Identifier: GPL-2.0 or BSD-3-Clause
2 
3 /* Authors: Bernard Metzler <bmt@zurich.ibm.com> */
4 /* Copyright (c) 2008-2019, IBM Corporation */
5 
6 #include <linux/errno.h>
7 #include <linux/types.h>
8 #include <linux/net.h>
9 #include <linux/scatterlist.h>
10 #include <linux/highmem.h>
11 #include <net/tcp.h>
12 
13 #include <rdma/iw_cm.h>
14 #include <rdma/ib_verbs.h>
15 #include <rdma/ib_user_verbs.h>
16 
17 #include "siw.h"
18 #include "siw_verbs.h"
19 #include "siw_mem.h"
20 
21 #define MAX_HDR_INLINE					\
22 	(((uint32_t)(sizeof(struct siw_rreq_pkt) -	\
23 		     sizeof(struct iwarp_send))) & 0xF8)
24 
25 static struct page *siw_get_pblpage(struct siw_mem *mem, u64 addr, int *idx)
26 {
27 	struct siw_pbl *pbl = mem->pbl;
28 	u64 offset = addr - mem->va;
29 	dma_addr_t paddr = siw_pbl_get_buffer(pbl, offset, NULL, idx);
30 
31 	if (paddr)
32 		return virt_to_page(paddr);
33 
34 	return NULL;
35 }
36 
37 /*
38  * Copy short payload at provided destination payload address
39  */
40 static int siw_try_1seg(struct siw_iwarp_tx *c_tx, void *paddr)
41 {
42 	struct siw_wqe *wqe = &c_tx->wqe_active;
43 	struct siw_sge *sge = &wqe->sqe.sge[0];
44 	u32 bytes = sge->length;
45 
46 	if (bytes > MAX_HDR_INLINE || wqe->sqe.num_sge != 1)
47 		return MAX_HDR_INLINE + 1;
48 
49 	if (!bytes)
50 		return 0;
51 
52 	if (tx_flags(wqe) & SIW_WQE_INLINE) {
53 		memcpy(paddr, &wqe->sqe.sge[1], bytes);
54 	} else {
55 		struct siw_mem *mem = wqe->mem[0];
56 
57 		if (!mem->mem_obj) {
58 			/* Kernel client using kva */
59 			memcpy(paddr,
60 			       (const void *)(uintptr_t)sge->laddr, bytes);
61 		} else if (c_tx->in_syscall) {
62 			if (copy_from_user(paddr, u64_to_user_ptr(sge->laddr),
63 					   bytes))
64 				return -EFAULT;
65 		} else {
66 			unsigned int off = sge->laddr & ~PAGE_MASK;
67 			struct page *p;
68 			char *buffer;
69 			int pbl_idx = 0;
70 
71 			if (!mem->is_pbl)
72 				p = siw_get_upage(mem->umem, sge->laddr);
73 			else
74 				p = siw_get_pblpage(mem, sge->laddr, &pbl_idx);
75 
76 			if (unlikely(!p))
77 				return -EFAULT;
78 
79 			buffer = kmap_atomic(p);
80 
81 			if (likely(PAGE_SIZE - off >= bytes)) {
82 				memcpy(paddr, buffer + off, bytes);
83 				kunmap_atomic(buffer);
84 			} else {
85 				unsigned long part = bytes - (PAGE_SIZE - off);
86 
87 				memcpy(paddr, buffer + off, part);
88 				kunmap_atomic(buffer);
89 
90 				if (!mem->is_pbl)
91 					p = siw_get_upage(mem->umem,
92 							  sge->laddr + part);
93 				else
94 					p = siw_get_pblpage(mem,
95 							    sge->laddr + part,
96 							    &pbl_idx);
97 				if (unlikely(!p))
98 					return -EFAULT;
99 
100 				buffer = kmap_atomic(p);
101 				memcpy(paddr + part, buffer,
102 				       bytes - part);
103 				kunmap_atomic(buffer);
104 			}
105 		}
106 	}
107 	return (int)bytes;
108 }
109 
110 #define PKT_FRAGMENTED 1
111 #define PKT_COMPLETE 0
112 
113 /*
114  * siw_qp_prepare_tx()
115  *
116  * Prepare tx state for sending out one fpdu. Builds complete pkt
117  * if no user data or only immediate data are present.
118  *
119  * returns PKT_COMPLETE if complete pkt built, PKT_FRAGMENTED otherwise.
120  */
121 static int siw_qp_prepare_tx(struct siw_iwarp_tx *c_tx)
122 {
123 	struct siw_wqe *wqe = &c_tx->wqe_active;
124 	char *crc = NULL;
125 	int data = 0;
126 
127 	switch (tx_type(wqe)) {
128 	case SIW_OP_READ:
129 	case SIW_OP_READ_LOCAL_INV:
130 		memcpy(&c_tx->pkt.ctrl,
131 		       &iwarp_pktinfo[RDMAP_RDMA_READ_REQ].ctrl,
132 		       sizeof(struct iwarp_ctrl));
133 
134 		c_tx->pkt.rreq.rsvd = 0;
135 		c_tx->pkt.rreq.ddp_qn = htonl(RDMAP_UNTAGGED_QN_RDMA_READ);
136 		c_tx->pkt.rreq.ddp_msn =
137 			htonl(++c_tx->ddp_msn[RDMAP_UNTAGGED_QN_RDMA_READ]);
138 		c_tx->pkt.rreq.ddp_mo = 0;
139 		c_tx->pkt.rreq.sink_stag = htonl(wqe->sqe.sge[0].lkey);
140 		c_tx->pkt.rreq.sink_to =
141 			cpu_to_be64(wqe->sqe.sge[0].laddr);
142 		c_tx->pkt.rreq.source_stag = htonl(wqe->sqe.rkey);
143 		c_tx->pkt.rreq.source_to = cpu_to_be64(wqe->sqe.raddr);
144 		c_tx->pkt.rreq.read_size = htonl(wqe->sqe.sge[0].length);
145 
146 		c_tx->ctrl_len = sizeof(struct iwarp_rdma_rreq);
147 		crc = (char *)&c_tx->pkt.rreq_pkt.crc;
148 		break;
149 
150 	case SIW_OP_SEND:
151 		if (tx_flags(wqe) & SIW_WQE_SOLICITED)
152 			memcpy(&c_tx->pkt.ctrl,
153 			       &iwarp_pktinfo[RDMAP_SEND_SE].ctrl,
154 			       sizeof(struct iwarp_ctrl));
155 		else
156 			memcpy(&c_tx->pkt.ctrl, &iwarp_pktinfo[RDMAP_SEND].ctrl,
157 			       sizeof(struct iwarp_ctrl));
158 
159 		c_tx->pkt.send.ddp_qn = RDMAP_UNTAGGED_QN_SEND;
160 		c_tx->pkt.send.ddp_msn =
161 			htonl(++c_tx->ddp_msn[RDMAP_UNTAGGED_QN_SEND]);
162 		c_tx->pkt.send.ddp_mo = 0;
163 
164 		c_tx->pkt.send_inv.inval_stag = 0;
165 
166 		c_tx->ctrl_len = sizeof(struct iwarp_send);
167 
168 		crc = (char *)&c_tx->pkt.send_pkt.crc;
169 		data = siw_try_1seg(c_tx, crc);
170 		break;
171 
172 	case SIW_OP_SEND_REMOTE_INV:
173 		if (tx_flags(wqe) & SIW_WQE_SOLICITED)
174 			memcpy(&c_tx->pkt.ctrl,
175 			       &iwarp_pktinfo[RDMAP_SEND_SE_INVAL].ctrl,
176 			       sizeof(struct iwarp_ctrl));
177 		else
178 			memcpy(&c_tx->pkt.ctrl,
179 			       &iwarp_pktinfo[RDMAP_SEND_INVAL].ctrl,
180 			       sizeof(struct iwarp_ctrl));
181 
182 		c_tx->pkt.send.ddp_qn = RDMAP_UNTAGGED_QN_SEND;
183 		c_tx->pkt.send.ddp_msn =
184 			htonl(++c_tx->ddp_msn[RDMAP_UNTAGGED_QN_SEND]);
185 		c_tx->pkt.send.ddp_mo = 0;
186 
187 		c_tx->pkt.send_inv.inval_stag = cpu_to_be32(wqe->sqe.rkey);
188 
189 		c_tx->ctrl_len = sizeof(struct iwarp_send_inv);
190 
191 		crc = (char *)&c_tx->pkt.send_pkt.crc;
192 		data = siw_try_1seg(c_tx, crc);
193 		break;
194 
195 	case SIW_OP_WRITE:
196 		memcpy(&c_tx->pkt.ctrl, &iwarp_pktinfo[RDMAP_RDMA_WRITE].ctrl,
197 		       sizeof(struct iwarp_ctrl));
198 
199 		c_tx->pkt.rwrite.sink_stag = htonl(wqe->sqe.rkey);
200 		c_tx->pkt.rwrite.sink_to = cpu_to_be64(wqe->sqe.raddr);
201 		c_tx->ctrl_len = sizeof(struct iwarp_rdma_write);
202 
203 		crc = (char *)&c_tx->pkt.write_pkt.crc;
204 		data = siw_try_1seg(c_tx, crc);
205 		break;
206 
207 	case SIW_OP_READ_RESPONSE:
208 		memcpy(&c_tx->pkt.ctrl,
209 		       &iwarp_pktinfo[RDMAP_RDMA_READ_RESP].ctrl,
210 		       sizeof(struct iwarp_ctrl));
211 
212 		/* NBO */
213 		c_tx->pkt.rresp.sink_stag = cpu_to_be32(wqe->sqe.rkey);
214 		c_tx->pkt.rresp.sink_to = cpu_to_be64(wqe->sqe.raddr);
215 
216 		c_tx->ctrl_len = sizeof(struct iwarp_rdma_rresp);
217 
218 		crc = (char *)&c_tx->pkt.write_pkt.crc;
219 		data = siw_try_1seg(c_tx, crc);
220 		break;
221 
222 	default:
223 		siw_dbg_qp(tx_qp(c_tx), "stale wqe type %d\n", tx_type(wqe));
224 		return -EOPNOTSUPP;
225 	}
226 	if (unlikely(data < 0))
227 		return data;
228 
229 	c_tx->ctrl_sent = 0;
230 
231 	if (data <= MAX_HDR_INLINE) {
232 		if (data) {
233 			wqe->processed = data;
234 
235 			c_tx->pkt.ctrl.mpa_len =
236 				htons(c_tx->ctrl_len + data - MPA_HDR_SIZE);
237 
238 			/* Add pad, if needed */
239 			data += -(int)data & 0x3;
240 			/* advance CRC location after payload */
241 			crc += data;
242 			c_tx->ctrl_len += data;
243 
244 			if (!(c_tx->pkt.ctrl.ddp_rdmap_ctrl & DDP_FLAG_TAGGED))
245 				c_tx->pkt.c_untagged.ddp_mo = 0;
246 			else
247 				c_tx->pkt.c_tagged.ddp_to =
248 					cpu_to_be64(wqe->sqe.raddr);
249 		}
250 
251 		*(u32 *)crc = 0;
252 		/*
253 		 * Do complete CRC if enabled and short packet
254 		 */
255 		if (c_tx->mpa_crc_hd) {
256 			crypto_shash_init(c_tx->mpa_crc_hd);
257 			if (crypto_shash_update(c_tx->mpa_crc_hd,
258 						(u8 *)&c_tx->pkt,
259 						c_tx->ctrl_len))
260 				return -EINVAL;
261 			crypto_shash_final(c_tx->mpa_crc_hd, (u8 *)crc);
262 		}
263 		c_tx->ctrl_len += MPA_CRC_SIZE;
264 
265 		return PKT_COMPLETE;
266 	}
267 	c_tx->ctrl_len += MPA_CRC_SIZE;
268 	c_tx->sge_idx = 0;
269 	c_tx->sge_off = 0;
270 	c_tx->pbl_idx = 0;
271 
272 	/*
273 	 * Allow direct sending out of user buffer if WR is non signalled
274 	 * and payload is over threshold.
275 	 * Per RDMA verbs, the application should not change the send buffer
276 	 * until the work completed. In iWarp, work completion is only
277 	 * local delivery to TCP. TCP may reuse the buffer for
278 	 * retransmission. Changing unsent data also breaks the CRC,
279 	 * if applied.
280 	 */
281 	if (c_tx->zcopy_tx && wqe->bytes >= SENDPAGE_THRESH &&
282 	    !(tx_flags(wqe) & SIW_WQE_SIGNALLED))
283 		c_tx->use_sendpage = 1;
284 	else
285 		c_tx->use_sendpage = 0;
286 
287 	return PKT_FRAGMENTED;
288 }
289 
290 /*
291  * Send out one complete control type FPDU, or header of FPDU carrying
292  * data. Used for fixed sized packets like Read.Requests or zero length
293  * SENDs, WRITEs, READ.Responses, or header only.
294  */
295 static int siw_tx_ctrl(struct siw_iwarp_tx *c_tx, struct socket *s,
296 			      int flags)
297 {
298 	struct msghdr msg = { .msg_flags = flags };
299 	struct kvec iov = { .iov_base =
300 				    (char *)&c_tx->pkt.ctrl + c_tx->ctrl_sent,
301 			    .iov_len = c_tx->ctrl_len - c_tx->ctrl_sent };
302 
303 	int rv = kernel_sendmsg(s, &msg, &iov, 1,
304 				c_tx->ctrl_len - c_tx->ctrl_sent);
305 
306 	if (rv >= 0) {
307 		c_tx->ctrl_sent += rv;
308 
309 		if (c_tx->ctrl_sent == c_tx->ctrl_len)
310 			rv = 0;
311 		else
312 			rv = -EAGAIN;
313 	}
314 	return rv;
315 }
316 
317 /*
318  * 0copy TCP transmit interface: Use do_tcp_sendpages.
319  *
320  * Using sendpage to push page by page appears to be less efficient
321  * than using sendmsg, even if data are copied.
322  *
323  * A general performance limitation might be the extra four bytes
324  * trailer checksum segment to be pushed after user data.
325  */
326 static int siw_tcp_sendpages(struct socket *s, struct page **page, int offset,
327 			     size_t size)
328 {
329 	struct sock *sk = s->sk;
330 	int i = 0, rv = 0, sent = 0,
331 	    flags = MSG_MORE | MSG_DONTWAIT | MSG_SENDPAGE_NOTLAST;
332 
333 	while (size) {
334 		size_t bytes = min_t(size_t, PAGE_SIZE - offset, size);
335 
336 		if (size + offset <= PAGE_SIZE)
337 			flags = MSG_MORE | MSG_DONTWAIT;
338 
339 		tcp_rate_check_app_limited(sk);
340 try_page_again:
341 		lock_sock(sk);
342 		rv = do_tcp_sendpages(sk, page[i], offset, bytes, flags);
343 		release_sock(sk);
344 
345 		if (rv > 0) {
346 			size -= rv;
347 			sent += rv;
348 			if (rv != bytes) {
349 				offset += rv;
350 				bytes -= rv;
351 				goto try_page_again;
352 			}
353 			offset = 0;
354 		} else {
355 			if (rv == -EAGAIN || rv == 0)
356 				break;
357 			return rv;
358 		}
359 		i++;
360 	}
361 	return sent;
362 }
363 
364 /*
365  * siw_0copy_tx()
366  *
367  * Pushes list of pages to TCP socket. If pages from multiple
368  * SGE's, all referenced pages of each SGE are pushed in one
369  * shot.
370  */
371 static int siw_0copy_tx(struct socket *s, struct page **page,
372 			struct siw_sge *sge, unsigned int offset,
373 			unsigned int size)
374 {
375 	int i = 0, sent = 0, rv;
376 	int sge_bytes = min(sge->length - offset, size);
377 
378 	offset = (sge->laddr + offset) & ~PAGE_MASK;
379 
380 	while (sent != size) {
381 		rv = siw_tcp_sendpages(s, &page[i], offset, sge_bytes);
382 		if (rv >= 0) {
383 			sent += rv;
384 			if (size == sent || sge_bytes > rv)
385 				break;
386 
387 			i += PAGE_ALIGN(sge_bytes + offset) >> PAGE_SHIFT;
388 			sge++;
389 			sge_bytes = min(sge->length, size - sent);
390 			offset = sge->laddr & ~PAGE_MASK;
391 		} else {
392 			sent = rv;
393 			break;
394 		}
395 	}
396 	return sent;
397 }
398 
399 #define MAX_TRAILER (MPA_CRC_SIZE + 4)
400 
401 static void siw_unmap_pages(struct page **pp, unsigned long kmap_mask)
402 {
403 	while (kmap_mask) {
404 		if (kmap_mask & BIT(0))
405 			kunmap(*pp);
406 		pp++;
407 		kmap_mask >>= 1;
408 	}
409 }
410 
411 /*
412  * siw_tx_hdt() tries to push a complete packet to TCP where all
413  * packet fragments are referenced by the elements of one iovec.
414  * For the data portion, each involved page must be referenced by
415  * one extra element. All sge's data can be non-aligned to page
416  * boundaries. Two more elements are referencing iWARP header
417  * and trailer:
418  * MAX_ARRAY = 64KB/PAGE_SIZE + 1 + (2 * (SIW_MAX_SGE - 1) + HDR + TRL
419  */
420 #define MAX_ARRAY ((0xffff / PAGE_SIZE) + 1 + (2 * (SIW_MAX_SGE - 1) + 2))
421 
422 /*
423  * Write out iov referencing hdr, data and trailer of current FPDU.
424  * Update transmit state dependent on write return status
425  */
426 static int siw_tx_hdt(struct siw_iwarp_tx *c_tx, struct socket *s)
427 {
428 	struct siw_wqe *wqe = &c_tx->wqe_active;
429 	struct siw_sge *sge = &wqe->sqe.sge[c_tx->sge_idx];
430 	struct kvec iov[MAX_ARRAY];
431 	struct page *page_array[MAX_ARRAY];
432 	struct msghdr msg = { .msg_flags = MSG_DONTWAIT | MSG_EOR };
433 
434 	int seg = 0, do_crc = c_tx->do_crc, is_kva = 0, rv;
435 	unsigned int data_len = c_tx->bytes_unsent, hdr_len = 0, trl_len = 0,
436 		     sge_off = c_tx->sge_off, sge_idx = c_tx->sge_idx,
437 		     pbl_idx = c_tx->pbl_idx;
438 	unsigned long kmap_mask = 0L;
439 
440 	if (c_tx->state == SIW_SEND_HDR) {
441 		if (c_tx->use_sendpage) {
442 			rv = siw_tx_ctrl(c_tx, s, MSG_DONTWAIT | MSG_MORE);
443 			if (rv)
444 				goto done;
445 
446 			c_tx->state = SIW_SEND_DATA;
447 		} else {
448 			iov[0].iov_base =
449 				(char *)&c_tx->pkt.ctrl + c_tx->ctrl_sent;
450 			iov[0].iov_len = hdr_len =
451 				c_tx->ctrl_len - c_tx->ctrl_sent;
452 			seg = 1;
453 		}
454 	}
455 
456 	wqe->processed += data_len;
457 
458 	while (data_len) { /* walk the list of SGE's */
459 		unsigned int sge_len = min(sge->length - sge_off, data_len);
460 		unsigned int fp_off = (sge->laddr + sge_off) & ~PAGE_MASK;
461 		struct siw_mem *mem;
462 
463 		if (!(tx_flags(wqe) & SIW_WQE_INLINE)) {
464 			mem = wqe->mem[sge_idx];
465 			is_kva = mem->mem_obj == NULL ? 1 : 0;
466 		} else {
467 			is_kva = 1;
468 		}
469 		if (is_kva && !c_tx->use_sendpage) {
470 			/*
471 			 * tx from kernel virtual address: either inline data
472 			 * or memory region with assigned kernel buffer
473 			 */
474 			iov[seg].iov_base =
475 				(void *)(uintptr_t)(sge->laddr + sge_off);
476 			iov[seg].iov_len = sge_len;
477 
478 			if (do_crc)
479 				crypto_shash_update(c_tx->mpa_crc_hd,
480 						    iov[seg].iov_base,
481 						    sge_len);
482 			sge_off += sge_len;
483 			data_len -= sge_len;
484 			seg++;
485 			goto sge_done;
486 		}
487 
488 		while (sge_len) {
489 			size_t plen = min((int)PAGE_SIZE - fp_off, sge_len);
490 
491 			if (!is_kva) {
492 				struct page *p;
493 
494 				if (mem->is_pbl)
495 					p = siw_get_pblpage(
496 						mem, sge->laddr + sge_off,
497 						&pbl_idx);
498 				else
499 					p = siw_get_upage(mem->umem,
500 							  sge->laddr + sge_off);
501 				if (unlikely(!p)) {
502 					siw_unmap_pages(page_array, kmap_mask);
503 					wqe->processed -= c_tx->bytes_unsent;
504 					rv = -EFAULT;
505 					goto done_crc;
506 				}
507 				page_array[seg] = p;
508 
509 				if (!c_tx->use_sendpage) {
510 					iov[seg].iov_base = kmap(p) + fp_off;
511 					iov[seg].iov_len = plen;
512 
513 					/* Remember for later kunmap() */
514 					kmap_mask |= BIT(seg);
515 
516 					if (do_crc)
517 						crypto_shash_update(
518 							c_tx->mpa_crc_hd,
519 							iov[seg].iov_base,
520 							plen);
521 				} else if (do_crc)
522 					crypto_shash_update(
523 						c_tx->mpa_crc_hd,
524 						page_address(p) + fp_off,
525 						plen);
526 			} else {
527 				u64 va = sge->laddr + sge_off;
528 
529 				page_array[seg] = virt_to_page(va & PAGE_MASK);
530 				if (do_crc)
531 					crypto_shash_update(
532 						c_tx->mpa_crc_hd,
533 						(void *)(uintptr_t)va,
534 						plen);
535 			}
536 
537 			sge_len -= plen;
538 			sge_off += plen;
539 			data_len -= plen;
540 			fp_off = 0;
541 
542 			if (++seg > (int)MAX_ARRAY) {
543 				siw_dbg_qp(tx_qp(c_tx), "to many fragments\n");
544 				siw_unmap_pages(page_array, kmap_mask);
545 				wqe->processed -= c_tx->bytes_unsent;
546 				rv = -EMSGSIZE;
547 				goto done_crc;
548 			}
549 		}
550 sge_done:
551 		/* Update SGE variables at end of SGE */
552 		if (sge_off == sge->length &&
553 		    (data_len != 0 || wqe->processed < wqe->bytes)) {
554 			sge_idx++;
555 			sge++;
556 			sge_off = 0;
557 		}
558 	}
559 	/* trailer */
560 	if (likely(c_tx->state != SIW_SEND_TRAILER)) {
561 		iov[seg].iov_base = &c_tx->trailer.pad[4 - c_tx->pad];
562 		iov[seg].iov_len = trl_len = MAX_TRAILER - (4 - c_tx->pad);
563 	} else {
564 		iov[seg].iov_base = &c_tx->trailer.pad[c_tx->ctrl_sent];
565 		iov[seg].iov_len = trl_len = MAX_TRAILER - c_tx->ctrl_sent;
566 	}
567 
568 	if (c_tx->pad) {
569 		*(u32 *)c_tx->trailer.pad = 0;
570 		if (do_crc)
571 			crypto_shash_update(c_tx->mpa_crc_hd,
572 				(u8 *)&c_tx->trailer.crc - c_tx->pad,
573 				c_tx->pad);
574 	}
575 	if (!c_tx->mpa_crc_hd)
576 		c_tx->trailer.crc = 0;
577 	else if (do_crc)
578 		crypto_shash_final(c_tx->mpa_crc_hd, (u8 *)&c_tx->trailer.crc);
579 
580 	data_len = c_tx->bytes_unsent;
581 
582 	if (c_tx->use_sendpage) {
583 		rv = siw_0copy_tx(s, page_array, &wqe->sqe.sge[c_tx->sge_idx],
584 				  c_tx->sge_off, data_len);
585 		if (rv == data_len) {
586 			rv = kernel_sendmsg(s, &msg, &iov[seg], 1, trl_len);
587 			if (rv > 0)
588 				rv += data_len;
589 			else
590 				rv = data_len;
591 		}
592 	} else {
593 		rv = kernel_sendmsg(s, &msg, iov, seg + 1,
594 				    hdr_len + data_len + trl_len);
595 		siw_unmap_pages(page_array, kmap_mask);
596 	}
597 	if (rv < (int)hdr_len) {
598 		/* Not even complete hdr pushed or negative rv */
599 		wqe->processed -= data_len;
600 		if (rv >= 0) {
601 			c_tx->ctrl_sent += rv;
602 			rv = -EAGAIN;
603 		}
604 		goto done_crc;
605 	}
606 	rv -= hdr_len;
607 
608 	if (rv >= (int)data_len) {
609 		/* all user data pushed to TCP or no data to push */
610 		if (data_len > 0 && wqe->processed < wqe->bytes) {
611 			/* Save the current state for next tx */
612 			c_tx->sge_idx = sge_idx;
613 			c_tx->sge_off = sge_off;
614 			c_tx->pbl_idx = pbl_idx;
615 		}
616 		rv -= data_len;
617 
618 		if (rv == trl_len) /* all pushed */
619 			rv = 0;
620 		else {
621 			c_tx->state = SIW_SEND_TRAILER;
622 			c_tx->ctrl_len = MAX_TRAILER;
623 			c_tx->ctrl_sent = rv + 4 - c_tx->pad;
624 			c_tx->bytes_unsent = 0;
625 			rv = -EAGAIN;
626 		}
627 
628 	} else if (data_len > 0) {
629 		/* Maybe some user data pushed to TCP */
630 		c_tx->state = SIW_SEND_DATA;
631 		wqe->processed -= data_len - rv;
632 
633 		if (rv) {
634 			/*
635 			 * Some bytes out. Recompute tx state based
636 			 * on old state and bytes pushed
637 			 */
638 			unsigned int sge_unsent;
639 
640 			c_tx->bytes_unsent -= rv;
641 			sge = &wqe->sqe.sge[c_tx->sge_idx];
642 			sge_unsent = sge->length - c_tx->sge_off;
643 
644 			while (sge_unsent <= rv) {
645 				rv -= sge_unsent;
646 				c_tx->sge_idx++;
647 				c_tx->sge_off = 0;
648 				sge++;
649 				sge_unsent = sge->length;
650 			}
651 			c_tx->sge_off += rv;
652 		}
653 		rv = -EAGAIN;
654 	}
655 done_crc:
656 	c_tx->do_crc = 0;
657 done:
658 	return rv;
659 }
660 
661 static void siw_update_tcpseg(struct siw_iwarp_tx *c_tx,
662 				     struct socket *s)
663 {
664 	struct tcp_sock *tp = tcp_sk(s->sk);
665 
666 	if (tp->gso_segs) {
667 		if (c_tx->gso_seg_limit == 0)
668 			c_tx->tcp_seglen = tp->mss_cache * tp->gso_segs;
669 		else
670 			c_tx->tcp_seglen =
671 				tp->mss_cache *
672 				min_t(u16, c_tx->gso_seg_limit, tp->gso_segs);
673 	} else {
674 		c_tx->tcp_seglen = tp->mss_cache;
675 	}
676 	/* Loopback may give odd numbers */
677 	c_tx->tcp_seglen &= 0xfffffff8;
678 }
679 
680 /*
681  * siw_prepare_fpdu()
682  *
683  * Prepares transmit context to send out one FPDU if FPDU will contain
684  * user data and user data are not immediate data.
685  * Computes maximum FPDU length to fill up TCP MSS if possible.
686  *
687  * @qp:		QP from which to transmit
688  * @wqe:	Current WQE causing transmission
689  *
690  * TODO: Take into account real available sendspace on socket
691  *       to avoid header misalignment due to send pausing within
692  *       fpdu transmission
693  */
694 static void siw_prepare_fpdu(struct siw_qp *qp, struct siw_wqe *wqe)
695 {
696 	struct siw_iwarp_tx *c_tx = &qp->tx_ctx;
697 	int data_len;
698 
699 	c_tx->ctrl_len =
700 		iwarp_pktinfo[__rdmap_get_opcode(&c_tx->pkt.ctrl)].hdr_len;
701 	c_tx->ctrl_sent = 0;
702 
703 	/*
704 	 * Update target buffer offset if any
705 	 */
706 	if (!(c_tx->pkt.ctrl.ddp_rdmap_ctrl & DDP_FLAG_TAGGED))
707 		/* Untagged message */
708 		c_tx->pkt.c_untagged.ddp_mo = cpu_to_be32(wqe->processed);
709 	else /* Tagged message */
710 		c_tx->pkt.c_tagged.ddp_to =
711 			cpu_to_be64(wqe->sqe.raddr + wqe->processed);
712 
713 	data_len = wqe->bytes - wqe->processed;
714 	if (data_len + c_tx->ctrl_len + MPA_CRC_SIZE > c_tx->tcp_seglen) {
715 		/* Trim DDP payload to fit into current TCP segment */
716 		data_len = c_tx->tcp_seglen - (c_tx->ctrl_len + MPA_CRC_SIZE);
717 		c_tx->pkt.ctrl.ddp_rdmap_ctrl &= ~DDP_FLAG_LAST;
718 		c_tx->pad = 0;
719 	} else {
720 		c_tx->pkt.ctrl.ddp_rdmap_ctrl |= DDP_FLAG_LAST;
721 		c_tx->pad = -data_len & 0x3;
722 	}
723 	c_tx->bytes_unsent = data_len;
724 
725 	c_tx->pkt.ctrl.mpa_len =
726 		htons(c_tx->ctrl_len + data_len - MPA_HDR_SIZE);
727 
728 	/*
729 	 * Init MPA CRC computation
730 	 */
731 	if (c_tx->mpa_crc_hd) {
732 		crypto_shash_init(c_tx->mpa_crc_hd);
733 		crypto_shash_update(c_tx->mpa_crc_hd, (u8 *)&c_tx->pkt,
734 				    c_tx->ctrl_len);
735 		c_tx->do_crc = 1;
736 	}
737 }
738 
739 /*
740  * siw_check_sgl_tx()
741  *
742  * Check permissions for a list of SGE's (SGL).
743  * A successful check will have all memory referenced
744  * for transmission resolved and assigned to the WQE.
745  *
746  * @pd:		Protection Domain SGL should belong to
747  * @wqe:	WQE to be checked
748  * @perms:	requested access permissions
749  *
750  */
751 
752 static int siw_check_sgl_tx(struct ib_pd *pd, struct siw_wqe *wqe,
753 			    enum ib_access_flags perms)
754 {
755 	struct siw_sge *sge = &wqe->sqe.sge[0];
756 	int i, len, num_sge = wqe->sqe.num_sge;
757 
758 	if (unlikely(num_sge > SIW_MAX_SGE))
759 		return -EINVAL;
760 
761 	for (i = 0, len = 0; num_sge; num_sge--, i++, sge++) {
762 		/*
763 		 * rdma verbs: do not check stag for a zero length sge
764 		 */
765 		if (sge->length) {
766 			int rv = siw_check_sge(pd, sge, &wqe->mem[i], perms, 0,
767 					       sge->length);
768 
769 			if (unlikely(rv != E_ACCESS_OK))
770 				return rv;
771 		}
772 		len += sge->length;
773 	}
774 	return len;
775 }
776 
777 /*
778  * siw_qp_sq_proc_tx()
779  *
780  * Process one WQE which needs transmission on the wire.
781  */
782 static int siw_qp_sq_proc_tx(struct siw_qp *qp, struct siw_wqe *wqe)
783 {
784 	struct siw_iwarp_tx *c_tx = &qp->tx_ctx;
785 	struct socket *s = qp->attrs.sk;
786 	int rv = 0, burst_len = qp->tx_ctx.burst;
787 	enum rdmap_ecode ecode = RDMAP_ECODE_CATASTROPHIC_STREAM;
788 
789 	if (unlikely(wqe->wr_status == SIW_WR_IDLE))
790 		return 0;
791 
792 	if (!burst_len)
793 		burst_len = SQ_USER_MAXBURST;
794 
795 	if (wqe->wr_status == SIW_WR_QUEUED) {
796 		if (!(wqe->sqe.flags & SIW_WQE_INLINE)) {
797 			if (tx_type(wqe) == SIW_OP_READ_RESPONSE)
798 				wqe->sqe.num_sge = 1;
799 
800 			if (tx_type(wqe) != SIW_OP_READ &&
801 			    tx_type(wqe) != SIW_OP_READ_LOCAL_INV) {
802 				/*
803 				 * Reference memory to be tx'd w/o checking
804 				 * access for LOCAL_READ permission, since
805 				 * not defined in RDMA core.
806 				 */
807 				rv = siw_check_sgl_tx(qp->pd, wqe, 0);
808 				if (rv < 0) {
809 					if (tx_type(wqe) ==
810 					    SIW_OP_READ_RESPONSE)
811 						ecode = siw_rdmap_error(-rv);
812 					rv = -EINVAL;
813 					goto tx_error;
814 				}
815 				wqe->bytes = rv;
816 			} else {
817 				wqe->bytes = 0;
818 			}
819 		} else {
820 			wqe->bytes = wqe->sqe.sge[0].length;
821 			if (!qp->kernel_verbs) {
822 				if (wqe->bytes > SIW_MAX_INLINE) {
823 					rv = -EINVAL;
824 					goto tx_error;
825 				}
826 				wqe->sqe.sge[0].laddr =
827 					(u64)(uintptr_t)&wqe->sqe.sge[1];
828 			}
829 		}
830 		wqe->wr_status = SIW_WR_INPROGRESS;
831 		wqe->processed = 0;
832 
833 		siw_update_tcpseg(c_tx, s);
834 
835 		rv = siw_qp_prepare_tx(c_tx);
836 		if (rv == PKT_FRAGMENTED) {
837 			c_tx->state = SIW_SEND_HDR;
838 			siw_prepare_fpdu(qp, wqe);
839 		} else if (rv == PKT_COMPLETE) {
840 			c_tx->state = SIW_SEND_SHORT_FPDU;
841 		} else {
842 			goto tx_error;
843 		}
844 	}
845 
846 next_segment:
847 	siw_dbg_qp(qp, "wr type %d, state %d, data %u, sent %u, id %llx\n",
848 		   tx_type(wqe), wqe->wr_status, wqe->bytes, wqe->processed,
849 		   wqe->sqe.id);
850 
851 	if (--burst_len == 0) {
852 		rv = -EINPROGRESS;
853 		goto tx_done;
854 	}
855 	if (c_tx->state == SIW_SEND_SHORT_FPDU) {
856 		enum siw_opcode tx_type = tx_type(wqe);
857 		unsigned int msg_flags;
858 
859 		if (siw_sq_empty(qp) || !siw_tcp_nagle || burst_len == 1)
860 			/*
861 			 * End current TCP segment, if SQ runs empty,
862 			 * or siw_tcp_nagle is not set, or we bail out
863 			 * soon due to no burst credit left.
864 			 */
865 			msg_flags = MSG_DONTWAIT;
866 		else
867 			msg_flags = MSG_DONTWAIT | MSG_MORE;
868 
869 		rv = siw_tx_ctrl(c_tx, s, msg_flags);
870 
871 		if (!rv && tx_type != SIW_OP_READ &&
872 		    tx_type != SIW_OP_READ_LOCAL_INV)
873 			wqe->processed = wqe->bytes;
874 
875 		goto tx_done;
876 
877 	} else {
878 		rv = siw_tx_hdt(c_tx, s);
879 	}
880 	if (!rv) {
881 		/*
882 		 * One segment sent. Processing completed if last
883 		 * segment, Do next segment otherwise.
884 		 */
885 		if (unlikely(c_tx->tx_suspend)) {
886 			/*
887 			 * Verbs, 6.4.: Try stopping sending after a full
888 			 * DDP segment if the connection goes down
889 			 * (== peer halfclose)
890 			 */
891 			rv = -ECONNABORTED;
892 			goto tx_done;
893 		}
894 		if (c_tx->pkt.ctrl.ddp_rdmap_ctrl & DDP_FLAG_LAST) {
895 			siw_dbg_qp(qp, "WQE completed\n");
896 			goto tx_done;
897 		}
898 		c_tx->state = SIW_SEND_HDR;
899 
900 		siw_update_tcpseg(c_tx, s);
901 
902 		siw_prepare_fpdu(qp, wqe);
903 		goto next_segment;
904 	}
905 tx_done:
906 	qp->tx_ctx.burst = burst_len;
907 	return rv;
908 
909 tx_error:
910 	if (ecode != RDMAP_ECODE_CATASTROPHIC_STREAM)
911 		siw_init_terminate(qp, TERM_ERROR_LAYER_RDMAP,
912 				   RDMAP_ETYPE_REMOTE_PROTECTION, ecode, 1);
913 	else
914 		siw_init_terminate(qp, TERM_ERROR_LAYER_RDMAP,
915 				   RDMAP_ETYPE_CATASTROPHIC,
916 				   RDMAP_ECODE_UNSPECIFIED, 1);
917 	return rv;
918 }
919 
920 static int siw_fastreg_mr(struct ib_pd *pd, struct siw_sqe *sqe)
921 {
922 	struct ib_mr *base_mr = (struct ib_mr *)(uintptr_t)sqe->base_mr;
923 	struct siw_device *sdev = to_siw_dev(pd->device);
924 	struct siw_mem *mem = siw_mem_id2obj(sdev, sqe->rkey  >> 8);
925 	int rv = 0;
926 
927 	siw_dbg_pd(pd, "STag 0x%08x\n", sqe->rkey);
928 
929 	if (unlikely(!mem || !base_mr)) {
930 		pr_warn("siw: fastreg: STag 0x%08x unknown\n", sqe->rkey);
931 		return -EINVAL;
932 	}
933 	if (unlikely(base_mr->rkey >> 8 != sqe->rkey  >> 8)) {
934 		pr_warn("siw: fastreg: STag 0x%08x: bad MR\n", sqe->rkey);
935 		rv = -EINVAL;
936 		goto out;
937 	}
938 	if (unlikely(mem->pd != pd)) {
939 		pr_warn("siw: fastreg: PD mismatch\n");
940 		rv = -EINVAL;
941 		goto out;
942 	}
943 	if (unlikely(mem->stag_valid)) {
944 		pr_warn("siw: fastreg: STag 0x%08x already valid\n", sqe->rkey);
945 		rv = -EINVAL;
946 		goto out;
947 	}
948 	/* Refresh STag since user may have changed key part */
949 	mem->stag = sqe->rkey;
950 	mem->perms = sqe->access;
951 
952 	siw_dbg_mem(mem, "STag 0x%08x now valid\n", sqe->rkey);
953 	mem->va = base_mr->iova;
954 	mem->stag_valid = 1;
955 out:
956 	siw_mem_put(mem);
957 	return rv;
958 }
959 
960 static int siw_qp_sq_proc_local(struct siw_qp *qp, struct siw_wqe *wqe)
961 {
962 	int rv;
963 
964 	switch (tx_type(wqe)) {
965 	case SIW_OP_REG_MR:
966 		rv = siw_fastreg_mr(qp->pd, &wqe->sqe);
967 		break;
968 
969 	case SIW_OP_INVAL_STAG:
970 		rv = siw_invalidate_stag(qp->pd, wqe->sqe.rkey);
971 		break;
972 
973 	default:
974 		rv = -EINVAL;
975 	}
976 	return rv;
977 }
978 
979 /*
980  * siw_qp_sq_process()
981  *
982  * Core TX path routine for RDMAP/DDP/MPA using a TCP kernel socket.
983  * Sends RDMAP payload for the current SQ WR @wqe of @qp in one or more
984  * MPA FPDUs, each containing a DDP segment.
985  *
986  * SQ processing may occur in user context as a result of posting
987  * new WQE's or from siw_sq_work_handler() context. Processing in
988  * user context is limited to non-kernel verbs users.
989  *
990  * SQ processing may get paused anytime, possibly in the middle of a WR
991  * or FPDU, if insufficient send space is available. SQ processing
992  * gets resumed from siw_sq_work_handler(), if send space becomes
993  * available again.
994  *
995  * Must be called with the QP state read-locked.
996  *
997  * Note:
998  * An outbound RREQ can be satisfied by the corresponding RRESP
999  * _before_ it gets assigned to the ORQ. This happens regularly
1000  * in RDMA READ via loopback case. Since both outbound RREQ and
1001  * inbound RRESP can be handled by the same CPU, locking the ORQ
1002  * is dead-lock prone and thus not an option. With that, the
1003  * RREQ gets assigned to the ORQ _before_ being sent - see
1004  * siw_activate_tx() - and pulled back in case of send failure.
1005  */
1006 int siw_qp_sq_process(struct siw_qp *qp)
1007 {
1008 	struct siw_wqe *wqe = tx_wqe(qp);
1009 	enum siw_opcode tx_type;
1010 	unsigned long flags;
1011 	int rv = 0;
1012 
1013 	siw_dbg_qp(qp, "enter for type %d\n", tx_type(wqe));
1014 
1015 next_wqe:
1016 	/*
1017 	 * Stop QP processing if SQ state changed
1018 	 */
1019 	if (unlikely(qp->tx_ctx.tx_suspend)) {
1020 		siw_dbg_qp(qp, "tx suspended\n");
1021 		goto done;
1022 	}
1023 	tx_type = tx_type(wqe);
1024 
1025 	if (tx_type <= SIW_OP_READ_RESPONSE)
1026 		rv = siw_qp_sq_proc_tx(qp, wqe);
1027 	else
1028 		rv = siw_qp_sq_proc_local(qp, wqe);
1029 
1030 	if (!rv) {
1031 		/*
1032 		 * WQE processing done
1033 		 */
1034 		switch (tx_type) {
1035 		case SIW_OP_SEND:
1036 		case SIW_OP_SEND_REMOTE_INV:
1037 		case SIW_OP_WRITE:
1038 			siw_wqe_put_mem(wqe, tx_type);
1039 			/* Fall through */
1040 
1041 		case SIW_OP_INVAL_STAG:
1042 		case SIW_OP_REG_MR:
1043 			if (tx_flags(wqe) & SIW_WQE_SIGNALLED)
1044 				siw_sqe_complete(qp, &wqe->sqe, wqe->bytes,
1045 						 SIW_WC_SUCCESS);
1046 			break;
1047 
1048 		case SIW_OP_READ:
1049 		case SIW_OP_READ_LOCAL_INV:
1050 			/*
1051 			 * already enqueued to ORQ queue
1052 			 */
1053 			break;
1054 
1055 		case SIW_OP_READ_RESPONSE:
1056 			siw_wqe_put_mem(wqe, tx_type);
1057 			break;
1058 
1059 		default:
1060 			WARN(1, "undefined WQE type %d\n", tx_type);
1061 			rv = -EINVAL;
1062 			goto done;
1063 		}
1064 
1065 		spin_lock_irqsave(&qp->sq_lock, flags);
1066 		wqe->wr_status = SIW_WR_IDLE;
1067 		rv = siw_activate_tx(qp);
1068 		spin_unlock_irqrestore(&qp->sq_lock, flags);
1069 
1070 		if (rv <= 0)
1071 			goto done;
1072 
1073 		goto next_wqe;
1074 
1075 	} else if (rv == -EAGAIN) {
1076 		siw_dbg_qp(qp, "sq paused: hd/tr %d of %d, data %d\n",
1077 			   qp->tx_ctx.ctrl_sent, qp->tx_ctx.ctrl_len,
1078 			   qp->tx_ctx.bytes_unsent);
1079 		rv = 0;
1080 		goto done;
1081 	} else if (rv == -EINPROGRESS) {
1082 		rv = siw_sq_start(qp);
1083 		goto done;
1084 	} else {
1085 		/*
1086 		 * WQE processing failed.
1087 		 * Verbs 8.3.2:
1088 		 * o It turns any WQE into a signalled WQE.
1089 		 * o Local catastrophic error must be surfaced
1090 		 * o QP must be moved into Terminate state: done by code
1091 		 *   doing socket state change processing
1092 		 *
1093 		 * o TODO: Termination message must be sent.
1094 		 * o TODO: Implement more precise work completion errors,
1095 		 *         see enum ib_wc_status in ib_verbs.h
1096 		 */
1097 		siw_dbg_qp(qp, "wqe type %d processing failed: %d\n",
1098 			   tx_type(wqe), rv);
1099 
1100 		spin_lock_irqsave(&qp->sq_lock, flags);
1101 		/*
1102 		 * RREQ may have already been completed by inbound RRESP!
1103 		 */
1104 		if (tx_type == SIW_OP_READ ||
1105 		    tx_type == SIW_OP_READ_LOCAL_INV) {
1106 			/* Cleanup pending entry in ORQ */
1107 			qp->orq_put--;
1108 			qp->orq[qp->orq_put % qp->attrs.orq_size].flags = 0;
1109 		}
1110 		spin_unlock_irqrestore(&qp->sq_lock, flags);
1111 		/*
1112 		 * immediately suspends further TX processing
1113 		 */
1114 		if (!qp->tx_ctx.tx_suspend)
1115 			siw_qp_cm_drop(qp, 0);
1116 
1117 		switch (tx_type) {
1118 		case SIW_OP_SEND:
1119 		case SIW_OP_SEND_REMOTE_INV:
1120 		case SIW_OP_SEND_WITH_IMM:
1121 		case SIW_OP_WRITE:
1122 		case SIW_OP_READ:
1123 		case SIW_OP_READ_LOCAL_INV:
1124 			siw_wqe_put_mem(wqe, tx_type);
1125 			/* Fall through */
1126 
1127 		case SIW_OP_INVAL_STAG:
1128 		case SIW_OP_REG_MR:
1129 			siw_sqe_complete(qp, &wqe->sqe, wqe->bytes,
1130 					 SIW_WC_LOC_QP_OP_ERR);
1131 
1132 			siw_qp_event(qp, IB_EVENT_QP_FATAL);
1133 
1134 			break;
1135 
1136 		case SIW_OP_READ_RESPONSE:
1137 			siw_dbg_qp(qp, "proc. read.response failed: %d\n", rv);
1138 
1139 			siw_qp_event(qp, IB_EVENT_QP_REQ_ERR);
1140 
1141 			siw_wqe_put_mem(wqe, SIW_OP_READ_RESPONSE);
1142 
1143 			break;
1144 
1145 		default:
1146 			WARN(1, "undefined WQE type %d\n", tx_type);
1147 			rv = -EINVAL;
1148 		}
1149 		wqe->wr_status = SIW_WR_IDLE;
1150 	}
1151 done:
1152 	return rv;
1153 }
1154 
1155 static void siw_sq_resume(struct siw_qp *qp)
1156 {
1157 	if (down_read_trylock(&qp->state_lock)) {
1158 		if (likely(qp->attrs.state == SIW_QP_STATE_RTS &&
1159 			   !qp->tx_ctx.tx_suspend)) {
1160 			int rv = siw_qp_sq_process(qp);
1161 
1162 			up_read(&qp->state_lock);
1163 
1164 			if (unlikely(rv < 0)) {
1165 				siw_dbg_qp(qp, "SQ task failed: err %d\n", rv);
1166 
1167 				if (!qp->tx_ctx.tx_suspend)
1168 					siw_qp_cm_drop(qp, 0);
1169 			}
1170 		} else {
1171 			up_read(&qp->state_lock);
1172 		}
1173 	} else {
1174 		siw_dbg_qp(qp, "Resume SQ while QP locked\n");
1175 	}
1176 	siw_qp_put(qp);
1177 }
1178 
1179 struct tx_task_t {
1180 	struct llist_head active;
1181 	wait_queue_head_t waiting;
1182 };
1183 
1184 static DEFINE_PER_CPU(struct tx_task_t, siw_tx_task_g);
1185 
1186 void siw_stop_tx_thread(int nr_cpu)
1187 {
1188 	kthread_stop(siw_tx_thread[nr_cpu]);
1189 	wake_up(&per_cpu(siw_tx_task_g, nr_cpu).waiting);
1190 }
1191 
1192 int siw_run_sq(void *data)
1193 {
1194 	const int nr_cpu = (unsigned int)(long)data;
1195 	struct llist_node *active;
1196 	struct siw_qp *qp;
1197 	struct tx_task_t *tx_task = &per_cpu(siw_tx_task_g, nr_cpu);
1198 
1199 	init_llist_head(&tx_task->active);
1200 	init_waitqueue_head(&tx_task->waiting);
1201 
1202 	while (1) {
1203 		struct llist_node *fifo_list = NULL;
1204 
1205 		wait_event_interruptible(tx_task->waiting,
1206 					 !llist_empty(&tx_task->active) ||
1207 						 kthread_should_stop());
1208 
1209 		if (kthread_should_stop())
1210 			break;
1211 
1212 		active = llist_del_all(&tx_task->active);
1213 		/*
1214 		 * llist_del_all returns a list with newest entry first.
1215 		 * Re-order list for fairness among QP's.
1216 		 */
1217 		while (active) {
1218 			struct llist_node *tmp = active;
1219 
1220 			active = llist_next(active);
1221 			tmp->next = fifo_list;
1222 			fifo_list = tmp;
1223 		}
1224 		while (fifo_list) {
1225 			qp = container_of(fifo_list, struct siw_qp, tx_list);
1226 			fifo_list = llist_next(fifo_list);
1227 			qp->tx_list.next = NULL;
1228 
1229 			siw_sq_resume(qp);
1230 		}
1231 	}
1232 	active = llist_del_all(&tx_task->active);
1233 	if (active) {
1234 		llist_for_each_entry(qp, active, tx_list) {
1235 			qp->tx_list.next = NULL;
1236 			siw_sq_resume(qp);
1237 		}
1238 	}
1239 	return 0;
1240 }
1241 
1242 int siw_sq_start(struct siw_qp *qp)
1243 {
1244 	if (tx_wqe(qp)->wr_status == SIW_WR_IDLE)
1245 		return 0;
1246 
1247 	if (unlikely(!cpu_online(qp->tx_cpu))) {
1248 		siw_put_tx_cpu(qp->tx_cpu);
1249 		qp->tx_cpu = siw_get_tx_cpu(qp->sdev);
1250 		if (qp->tx_cpu < 0) {
1251 			pr_warn("siw: no tx cpu available\n");
1252 
1253 			return -EIO;
1254 		}
1255 	}
1256 	siw_qp_get(qp);
1257 
1258 	llist_add(&qp->tx_list, &per_cpu(siw_tx_task_g, qp->tx_cpu).active);
1259 
1260 	wake_up(&per_cpu(siw_tx_task_g, qp->tx_cpu).waiting);
1261 
1262 	return 0;
1263 }
1264