xref: /linux/drivers/infiniband/sw/siw/siw_qp_tx.c (revision eb01fe7abbe2d0b38824d2a93fdb4cc3eaf2ccc1)
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 ib_virt_dma_to_page(paddr);
33 
34 	return NULL;
35 }
36 
37 static struct page *siw_get_page(struct siw_mem *mem, struct siw_sge *sge,
38 				 unsigned long offset, int *pbl_idx)
39 {
40 	if (!mem->is_pbl)
41 		return siw_get_upage(mem->umem, sge->laddr + offset);
42 	else
43 		return siw_get_pblpage(mem, sge->laddr + offset, pbl_idx);
44 }
45 
46 /*
47  * Copy short payload at provided destination payload address
48  */
49 static int siw_try_1seg(struct siw_iwarp_tx *c_tx, void *paddr)
50 {
51 	struct siw_wqe *wqe = &c_tx->wqe_active;
52 	struct siw_sge *sge = &wqe->sqe.sge[0];
53 	u32 bytes = sge->length;
54 
55 	if (bytes > MAX_HDR_INLINE || wqe->sqe.num_sge != 1)
56 		return MAX_HDR_INLINE + 1;
57 
58 	if (!bytes)
59 		return 0;
60 
61 	if (tx_flags(wqe) & SIW_WQE_INLINE) {
62 		memcpy(paddr, &wqe->sqe.sge[1], bytes);
63 	} else {
64 		struct siw_mem *mem = wqe->mem[0];
65 
66 		if (!mem->mem_obj) {
67 			/* Kernel client using kva */
68 			memcpy(paddr, ib_virt_dma_to_ptr(sge->laddr), bytes);
69 		} else if (c_tx->in_syscall) {
70 			if (copy_from_user(paddr, u64_to_user_ptr(sge->laddr),
71 					   bytes))
72 				return -EFAULT;
73 		} else {
74 			unsigned int off = sge->laddr & ~PAGE_MASK;
75 			struct page *p;
76 			char *buffer;
77 			int pbl_idx = 0;
78 
79 			p = siw_get_page(mem, sge, 0, &pbl_idx);
80 			if (unlikely(!p))
81 				return -EFAULT;
82 
83 			buffer = kmap_local_page(p);
84 
85 			if (likely(PAGE_SIZE - off >= bytes)) {
86 				memcpy(paddr, buffer + off, bytes);
87 			} else {
88 				unsigned long part = bytes - (PAGE_SIZE - off);
89 
90 				memcpy(paddr, buffer + off, part);
91 				kunmap_local(buffer);
92 
93 				p = siw_get_page(mem, sge, part, &pbl_idx);
94 				if (unlikely(!p))
95 					return -EFAULT;
96 
97 				buffer = kmap_local_page(p);
98 				memcpy(paddr + part, buffer, bytes - part);
99 			}
100 			kunmap_local(buffer);
101 		}
102 	}
103 	return (int)bytes;
104 }
105 
106 #define PKT_FRAGMENTED 1
107 #define PKT_COMPLETE 0
108 
109 /*
110  * siw_qp_prepare_tx()
111  *
112  * Prepare tx state for sending out one fpdu. Builds complete pkt
113  * if no user data or only immediate data are present.
114  *
115  * returns PKT_COMPLETE if complete pkt built, PKT_FRAGMENTED otherwise.
116  */
117 static int siw_qp_prepare_tx(struct siw_iwarp_tx *c_tx)
118 {
119 	struct siw_wqe *wqe = &c_tx->wqe_active;
120 	char *crc = NULL;
121 	int data = 0;
122 
123 	switch (tx_type(wqe)) {
124 	case SIW_OP_READ:
125 	case SIW_OP_READ_LOCAL_INV:
126 		memcpy(&c_tx->pkt.ctrl,
127 		       &iwarp_pktinfo[RDMAP_RDMA_READ_REQ].ctrl,
128 		       sizeof(struct iwarp_ctrl));
129 
130 		c_tx->pkt.rreq.rsvd = 0;
131 		c_tx->pkt.rreq.ddp_qn = htonl(RDMAP_UNTAGGED_QN_RDMA_READ);
132 		c_tx->pkt.rreq.ddp_msn =
133 			htonl(++c_tx->ddp_msn[RDMAP_UNTAGGED_QN_RDMA_READ]);
134 		c_tx->pkt.rreq.ddp_mo = 0;
135 		c_tx->pkt.rreq.sink_stag = htonl(wqe->sqe.sge[0].lkey);
136 		c_tx->pkt.rreq.sink_to =
137 			cpu_to_be64(wqe->sqe.sge[0].laddr);
138 		c_tx->pkt.rreq.source_stag = htonl(wqe->sqe.rkey);
139 		c_tx->pkt.rreq.source_to = cpu_to_be64(wqe->sqe.raddr);
140 		c_tx->pkt.rreq.read_size = htonl(wqe->sqe.sge[0].length);
141 
142 		c_tx->ctrl_len = sizeof(struct iwarp_rdma_rreq);
143 		crc = (char *)&c_tx->pkt.rreq_pkt.crc;
144 		break;
145 
146 	case SIW_OP_SEND:
147 		if (tx_flags(wqe) & SIW_WQE_SOLICITED)
148 			memcpy(&c_tx->pkt.ctrl,
149 			       &iwarp_pktinfo[RDMAP_SEND_SE].ctrl,
150 			       sizeof(struct iwarp_ctrl));
151 		else
152 			memcpy(&c_tx->pkt.ctrl, &iwarp_pktinfo[RDMAP_SEND].ctrl,
153 			       sizeof(struct iwarp_ctrl));
154 
155 		c_tx->pkt.send.ddp_qn = RDMAP_UNTAGGED_QN_SEND;
156 		c_tx->pkt.send.ddp_msn =
157 			htonl(++c_tx->ddp_msn[RDMAP_UNTAGGED_QN_SEND]);
158 		c_tx->pkt.send.ddp_mo = 0;
159 
160 		c_tx->pkt.send_inv.inval_stag = 0;
161 
162 		c_tx->ctrl_len = sizeof(struct iwarp_send);
163 
164 		crc = (char *)&c_tx->pkt.send_pkt.crc;
165 		data = siw_try_1seg(c_tx, crc);
166 		break;
167 
168 	case SIW_OP_SEND_REMOTE_INV:
169 		if (tx_flags(wqe) & SIW_WQE_SOLICITED)
170 			memcpy(&c_tx->pkt.ctrl,
171 			       &iwarp_pktinfo[RDMAP_SEND_SE_INVAL].ctrl,
172 			       sizeof(struct iwarp_ctrl));
173 		else
174 			memcpy(&c_tx->pkt.ctrl,
175 			       &iwarp_pktinfo[RDMAP_SEND_INVAL].ctrl,
176 			       sizeof(struct iwarp_ctrl));
177 
178 		c_tx->pkt.send.ddp_qn = RDMAP_UNTAGGED_QN_SEND;
179 		c_tx->pkt.send.ddp_msn =
180 			htonl(++c_tx->ddp_msn[RDMAP_UNTAGGED_QN_SEND]);
181 		c_tx->pkt.send.ddp_mo = 0;
182 
183 		c_tx->pkt.send_inv.inval_stag = cpu_to_be32(wqe->sqe.rkey);
184 
185 		c_tx->ctrl_len = sizeof(struct iwarp_send_inv);
186 
187 		crc = (char *)&c_tx->pkt.send_pkt.crc;
188 		data = siw_try_1seg(c_tx, crc);
189 		break;
190 
191 	case SIW_OP_WRITE:
192 		memcpy(&c_tx->pkt.ctrl, &iwarp_pktinfo[RDMAP_RDMA_WRITE].ctrl,
193 		       sizeof(struct iwarp_ctrl));
194 
195 		c_tx->pkt.rwrite.sink_stag = htonl(wqe->sqe.rkey);
196 		c_tx->pkt.rwrite.sink_to = cpu_to_be64(wqe->sqe.raddr);
197 		c_tx->ctrl_len = sizeof(struct iwarp_rdma_write);
198 
199 		crc = (char *)&c_tx->pkt.write_pkt.crc;
200 		data = siw_try_1seg(c_tx, crc);
201 		break;
202 
203 	case SIW_OP_READ_RESPONSE:
204 		memcpy(&c_tx->pkt.ctrl,
205 		       &iwarp_pktinfo[RDMAP_RDMA_READ_RESP].ctrl,
206 		       sizeof(struct iwarp_ctrl));
207 
208 		/* NBO */
209 		c_tx->pkt.rresp.sink_stag = cpu_to_be32(wqe->sqe.rkey);
210 		c_tx->pkt.rresp.sink_to = cpu_to_be64(wqe->sqe.raddr);
211 
212 		c_tx->ctrl_len = sizeof(struct iwarp_rdma_rresp);
213 
214 		crc = (char *)&c_tx->pkt.write_pkt.crc;
215 		data = siw_try_1seg(c_tx, crc);
216 		break;
217 
218 	default:
219 		siw_dbg_qp(tx_qp(c_tx), "stale wqe type %d\n", tx_type(wqe));
220 		return -EOPNOTSUPP;
221 	}
222 	if (unlikely(data < 0))
223 		return data;
224 
225 	c_tx->ctrl_sent = 0;
226 
227 	if (data <= MAX_HDR_INLINE) {
228 		if (data) {
229 			wqe->processed = data;
230 
231 			c_tx->pkt.ctrl.mpa_len =
232 				htons(c_tx->ctrl_len + data - MPA_HDR_SIZE);
233 
234 			/* Add pad, if needed */
235 			data += -(int)data & 0x3;
236 			/* advance CRC location after payload */
237 			crc += data;
238 			c_tx->ctrl_len += data;
239 
240 			if (!(c_tx->pkt.ctrl.ddp_rdmap_ctrl & DDP_FLAG_TAGGED))
241 				c_tx->pkt.c_untagged.ddp_mo = 0;
242 			else
243 				c_tx->pkt.c_tagged.ddp_to =
244 					cpu_to_be64(wqe->sqe.raddr);
245 		}
246 
247 		*(u32 *)crc = 0;
248 		/*
249 		 * Do complete CRC if enabled and short packet
250 		 */
251 		if (c_tx->mpa_crc_hd &&
252 		    crypto_shash_digest(c_tx->mpa_crc_hd, (u8 *)&c_tx->pkt,
253 					c_tx->ctrl_len, (u8 *)crc) != 0)
254 			return -EINVAL;
255 		c_tx->ctrl_len += MPA_CRC_SIZE;
256 
257 		return PKT_COMPLETE;
258 	}
259 	c_tx->ctrl_len += MPA_CRC_SIZE;
260 	c_tx->sge_idx = 0;
261 	c_tx->sge_off = 0;
262 	c_tx->pbl_idx = 0;
263 
264 	/*
265 	 * Allow direct sending out of user buffer if WR is non signalled
266 	 * and payload is over threshold.
267 	 * Per RDMA verbs, the application should not change the send buffer
268 	 * until the work completed. In iWarp, work completion is only
269 	 * local delivery to TCP. TCP may reuse the buffer for
270 	 * retransmission. Changing unsent data also breaks the CRC,
271 	 * if applied.
272 	 */
273 	if (c_tx->zcopy_tx && wqe->bytes >= SENDPAGE_THRESH &&
274 	    !(tx_flags(wqe) & SIW_WQE_SIGNALLED))
275 		c_tx->use_sendpage = 1;
276 	else
277 		c_tx->use_sendpage = 0;
278 
279 	return PKT_FRAGMENTED;
280 }
281 
282 /*
283  * Send out one complete control type FPDU, or header of FPDU carrying
284  * data. Used for fixed sized packets like Read.Requests or zero length
285  * SENDs, WRITEs, READ.Responses, or header only.
286  */
287 static int siw_tx_ctrl(struct siw_iwarp_tx *c_tx, struct socket *s,
288 			      int flags)
289 {
290 	struct msghdr msg = { .msg_flags = flags };
291 	struct kvec iov = { .iov_base =
292 				    (char *)&c_tx->pkt.ctrl + c_tx->ctrl_sent,
293 			    .iov_len = c_tx->ctrl_len - c_tx->ctrl_sent };
294 
295 	int rv = kernel_sendmsg(s, &msg, &iov, 1, iov.iov_len);
296 
297 	if (rv >= 0) {
298 		c_tx->ctrl_sent += rv;
299 
300 		if (c_tx->ctrl_sent == c_tx->ctrl_len)
301 			rv = 0;
302 		else
303 			rv = -EAGAIN;
304 	}
305 	return rv;
306 }
307 
308 /*
309  * 0copy TCP transmit interface: Use MSG_SPLICE_PAGES.
310  *
311  * Using sendpage to push page by page appears to be less efficient
312  * than using sendmsg, even if data are copied.
313  *
314  * A general performance limitation might be the extra four bytes
315  * trailer checksum segment to be pushed after user data.
316  */
317 static int siw_tcp_sendpages(struct socket *s, struct page **page, int offset,
318 			     size_t size)
319 {
320 	struct bio_vec bvec;
321 	struct msghdr msg = {
322 		.msg_flags = (MSG_MORE | MSG_DONTWAIT | MSG_SPLICE_PAGES),
323 	};
324 	struct sock *sk = s->sk;
325 	int i = 0, rv = 0, sent = 0;
326 
327 	while (size) {
328 		size_t bytes = min_t(size_t, PAGE_SIZE - offset, size);
329 
330 		if (size + offset <= PAGE_SIZE)
331 			msg.msg_flags &= ~MSG_MORE;
332 
333 		tcp_rate_check_app_limited(sk);
334 		bvec_set_page(&bvec, page[i], bytes, offset);
335 		iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, size);
336 
337 try_page_again:
338 		lock_sock(sk);
339 		rv = tcp_sendmsg_locked(sk, &msg, size);
340 		release_sock(sk);
341 
342 		if (rv > 0) {
343 			size -= rv;
344 			sent += rv;
345 			if (rv != bytes) {
346 				offset += rv;
347 				bytes -= rv;
348 				goto try_page_again;
349 			}
350 			offset = 0;
351 		} else {
352 			if (rv == -EAGAIN || rv == 0)
353 				break;
354 			return rv;
355 		}
356 		i++;
357 	}
358 	return sent;
359 }
360 
361 /*
362  * siw_0copy_tx()
363  *
364  * Pushes list of pages to TCP socket. If pages from multiple
365  * SGE's, all referenced pages of each SGE are pushed in one
366  * shot.
367  */
368 static int siw_0copy_tx(struct socket *s, struct page **page,
369 			struct siw_sge *sge, unsigned int offset,
370 			unsigned int size)
371 {
372 	int i = 0, sent = 0, rv;
373 	int sge_bytes = min(sge->length - offset, size);
374 
375 	offset = (sge->laddr + offset) & ~PAGE_MASK;
376 
377 	while (sent != size) {
378 		rv = siw_tcp_sendpages(s, &page[i], offset, sge_bytes);
379 		if (rv >= 0) {
380 			sent += rv;
381 			if (size == sent || sge_bytes > rv)
382 				break;
383 
384 			i += PAGE_ALIGN(sge_bytes + offset) >> PAGE_SHIFT;
385 			sge++;
386 			sge_bytes = min(sge->length, size - sent);
387 			offset = sge->laddr & ~PAGE_MASK;
388 		} else {
389 			sent = rv;
390 			break;
391 		}
392 	}
393 	return sent;
394 }
395 
396 #define MAX_TRAILER (MPA_CRC_SIZE + 4)
397 
398 static void siw_unmap_pages(struct kvec *iov, unsigned long kmap_mask, int len)
399 {
400 	int i;
401 
402 	/*
403 	 * Work backwards through the array to honor the kmap_local_page()
404 	 * ordering requirements.
405 	 */
406 	for (i = (len-1); i >= 0; i--) {
407 		if (kmap_mask & BIT(i)) {
408 			unsigned long addr = (unsigned long)iov[i].iov_base;
409 
410 			kunmap_local((void *)(addr & PAGE_MASK));
411 		}
412 	}
413 }
414 
415 /*
416  * siw_tx_hdt() tries to push a complete packet to TCP where all
417  * packet fragments are referenced by the elements of one iovec.
418  * For the data portion, each involved page must be referenced by
419  * one extra element. All sge's data can be non-aligned to page
420  * boundaries. Two more elements are referencing iWARP header
421  * and trailer:
422  * MAX_ARRAY = 64KB/PAGE_SIZE + 1 + (2 * (SIW_MAX_SGE - 1) + HDR + TRL
423  */
424 #define MAX_ARRAY ((0xffff / PAGE_SIZE) + 1 + (2 * (SIW_MAX_SGE - 1) + 2))
425 
426 /*
427  * Write out iov referencing hdr, data and trailer of current FPDU.
428  * Update transmit state dependent on write return status
429  */
430 static int siw_tx_hdt(struct siw_iwarp_tx *c_tx, struct socket *s)
431 {
432 	struct siw_wqe *wqe = &c_tx->wqe_active;
433 	struct siw_sge *sge = &wqe->sqe.sge[c_tx->sge_idx];
434 	struct kvec iov[MAX_ARRAY];
435 	struct page *page_array[MAX_ARRAY];
436 	struct msghdr msg = { .msg_flags = MSG_DONTWAIT | MSG_EOR };
437 
438 	int seg = 0, do_crc = c_tx->do_crc, is_kva = 0, rv;
439 	unsigned int data_len = c_tx->bytes_unsent, hdr_len = 0, trl_len = 0,
440 		     sge_off = c_tx->sge_off, sge_idx = c_tx->sge_idx,
441 		     pbl_idx = c_tx->pbl_idx;
442 	unsigned long kmap_mask = 0L;
443 
444 	if (c_tx->state == SIW_SEND_HDR) {
445 		if (c_tx->use_sendpage) {
446 			rv = siw_tx_ctrl(c_tx, s, MSG_DONTWAIT | MSG_MORE);
447 			if (rv)
448 				goto done;
449 
450 			c_tx->state = SIW_SEND_DATA;
451 		} else {
452 			iov[0].iov_base =
453 				(char *)&c_tx->pkt.ctrl + c_tx->ctrl_sent;
454 			iov[0].iov_len = hdr_len =
455 				c_tx->ctrl_len - c_tx->ctrl_sent;
456 			seg = 1;
457 		}
458 	}
459 
460 	wqe->processed += data_len;
461 
462 	while (data_len) { /* walk the list of SGE's */
463 		unsigned int sge_len = min(sge->length - sge_off, data_len);
464 		unsigned int fp_off = (sge->laddr + sge_off) & ~PAGE_MASK;
465 		struct siw_mem *mem;
466 
467 		if (!(tx_flags(wqe) & SIW_WQE_INLINE)) {
468 			mem = wqe->mem[sge_idx];
469 			is_kva = mem->mem_obj == NULL ? 1 : 0;
470 		} else {
471 			is_kva = 1;
472 		}
473 		if (is_kva && !c_tx->use_sendpage) {
474 			/*
475 			 * tx from kernel virtual address: either inline data
476 			 * or memory region with assigned kernel buffer
477 			 */
478 			iov[seg].iov_base =
479 				ib_virt_dma_to_ptr(sge->laddr + sge_off);
480 			iov[seg].iov_len = sge_len;
481 
482 			if (do_crc)
483 				crypto_shash_update(c_tx->mpa_crc_hd,
484 						    iov[seg].iov_base,
485 						    sge_len);
486 			sge_off += sge_len;
487 			data_len -= sge_len;
488 			seg++;
489 			goto sge_done;
490 		}
491 
492 		while (sge_len) {
493 			size_t plen = min((int)PAGE_SIZE - fp_off, sge_len);
494 			void *kaddr;
495 
496 			if (!is_kva) {
497 				struct page *p;
498 
499 				p = siw_get_page(mem, sge, sge_off, &pbl_idx);
500 				if (unlikely(!p)) {
501 					siw_unmap_pages(iov, kmap_mask, seg);
502 					wqe->processed -= c_tx->bytes_unsent;
503 					rv = -EFAULT;
504 					goto done_crc;
505 				}
506 				page_array[seg] = p;
507 
508 				if (!c_tx->use_sendpage) {
509 					void *kaddr = kmap_local_page(p);
510 
511 					/* Remember for later kunmap() */
512 					kmap_mask |= BIT(seg);
513 					iov[seg].iov_base = kaddr + fp_off;
514 					iov[seg].iov_len = plen;
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 					kaddr = kmap_local_page(p);
523 					crypto_shash_update(c_tx->mpa_crc_hd,
524 							    kaddr + fp_off,
525 							    plen);
526 					kunmap_local(kaddr);
527 				}
528 			} else {
529 				/*
530 				 * Cast to an uintptr_t to preserve all 64 bits
531 				 * in sge->laddr.
532 				 */
533 				u64 va = sge->laddr + sge_off;
534 
535 				page_array[seg] = ib_virt_dma_to_page(va);
536 				if (do_crc)
537 					crypto_shash_update(
538 						c_tx->mpa_crc_hd,
539 						ib_virt_dma_to_ptr(va),
540 						plen);
541 			}
542 
543 			sge_len -= plen;
544 			sge_off += plen;
545 			data_len -= plen;
546 			fp_off = 0;
547 
548 			if (++seg >= (int)MAX_ARRAY) {
549 				siw_dbg_qp(tx_qp(c_tx), "to many fragments\n");
550 				siw_unmap_pages(iov, kmap_mask, seg-1);
551 				wqe->processed -= c_tx->bytes_unsent;
552 				rv = -EMSGSIZE;
553 				goto done_crc;
554 			}
555 		}
556 sge_done:
557 		/* Update SGE variables at end of SGE */
558 		if (sge_off == sge->length &&
559 		    (data_len != 0 || wqe->processed < wqe->bytes)) {
560 			sge_idx++;
561 			sge++;
562 			sge_off = 0;
563 		}
564 	}
565 	/* trailer */
566 	if (likely(c_tx->state != SIW_SEND_TRAILER)) {
567 		iov[seg].iov_base = &c_tx->trailer.pad[4 - c_tx->pad];
568 		iov[seg].iov_len = trl_len = MAX_TRAILER - (4 - c_tx->pad);
569 	} else {
570 		iov[seg].iov_base = &c_tx->trailer.pad[c_tx->ctrl_sent];
571 		iov[seg].iov_len = trl_len = MAX_TRAILER - c_tx->ctrl_sent;
572 	}
573 
574 	if (c_tx->pad) {
575 		*(u32 *)c_tx->trailer.pad = 0;
576 		if (do_crc)
577 			crypto_shash_update(c_tx->mpa_crc_hd,
578 				(u8 *)&c_tx->trailer.crc - c_tx->pad,
579 				c_tx->pad);
580 	}
581 	if (!c_tx->mpa_crc_hd)
582 		c_tx->trailer.crc = 0;
583 	else if (do_crc)
584 		crypto_shash_final(c_tx->mpa_crc_hd, (u8 *)&c_tx->trailer.crc);
585 
586 	data_len = c_tx->bytes_unsent;
587 
588 	if (c_tx->use_sendpage) {
589 		rv = siw_0copy_tx(s, page_array, &wqe->sqe.sge[c_tx->sge_idx],
590 				  c_tx->sge_off, data_len);
591 		if (rv == data_len) {
592 			rv = kernel_sendmsg(s, &msg, &iov[seg], 1, trl_len);
593 			if (rv > 0)
594 				rv += data_len;
595 			else
596 				rv = data_len;
597 		}
598 	} else {
599 		rv = kernel_sendmsg(s, &msg, iov, seg + 1,
600 				    hdr_len + data_len + trl_len);
601 		siw_unmap_pages(iov, kmap_mask, seg);
602 	}
603 	if (rv < (int)hdr_len) {
604 		/* Not even complete hdr pushed or negative rv */
605 		wqe->processed -= data_len;
606 		if (rv >= 0) {
607 			c_tx->ctrl_sent += rv;
608 			rv = -EAGAIN;
609 		}
610 		goto done_crc;
611 	}
612 	rv -= hdr_len;
613 
614 	if (rv >= (int)data_len) {
615 		/* all user data pushed to TCP or no data to push */
616 		if (data_len > 0 && wqe->processed < wqe->bytes) {
617 			/* Save the current state for next tx */
618 			c_tx->sge_idx = sge_idx;
619 			c_tx->sge_off = sge_off;
620 			c_tx->pbl_idx = pbl_idx;
621 		}
622 		rv -= data_len;
623 
624 		if (rv == trl_len) /* all pushed */
625 			rv = 0;
626 		else {
627 			c_tx->state = SIW_SEND_TRAILER;
628 			c_tx->ctrl_len = MAX_TRAILER;
629 			c_tx->ctrl_sent = rv + 4 - c_tx->pad;
630 			c_tx->bytes_unsent = 0;
631 			rv = -EAGAIN;
632 		}
633 
634 	} else if (data_len > 0) {
635 		/* Maybe some user data pushed to TCP */
636 		c_tx->state = SIW_SEND_DATA;
637 		wqe->processed -= data_len - rv;
638 
639 		if (rv) {
640 			/*
641 			 * Some bytes out. Recompute tx state based
642 			 * on old state and bytes pushed
643 			 */
644 			unsigned int sge_unsent;
645 
646 			c_tx->bytes_unsent -= rv;
647 			sge = &wqe->sqe.sge[c_tx->sge_idx];
648 			sge_unsent = sge->length - c_tx->sge_off;
649 
650 			while (sge_unsent <= rv) {
651 				rv -= sge_unsent;
652 				c_tx->sge_idx++;
653 				c_tx->sge_off = 0;
654 				sge++;
655 				sge_unsent = sge->length;
656 			}
657 			c_tx->sge_off += rv;
658 		}
659 		rv = -EAGAIN;
660 	}
661 done_crc:
662 	c_tx->do_crc = 0;
663 done:
664 	return rv;
665 }
666 
667 static void siw_update_tcpseg(struct siw_iwarp_tx *c_tx,
668 				     struct socket *s)
669 {
670 	struct tcp_sock *tp = tcp_sk(s->sk);
671 
672 	if (tp->gso_segs) {
673 		if (c_tx->gso_seg_limit == 0)
674 			c_tx->tcp_seglen = tp->mss_cache * tp->gso_segs;
675 		else
676 			c_tx->tcp_seglen =
677 				tp->mss_cache *
678 				min_t(u16, c_tx->gso_seg_limit, tp->gso_segs);
679 	} else {
680 		c_tx->tcp_seglen = tp->mss_cache;
681 	}
682 	/* Loopback may give odd numbers */
683 	c_tx->tcp_seglen &= 0xfffffff8;
684 }
685 
686 /*
687  * siw_prepare_fpdu()
688  *
689  * Prepares transmit context to send out one FPDU if FPDU will contain
690  * user data and user data are not immediate data.
691  * Computes maximum FPDU length to fill up TCP MSS if possible.
692  *
693  * @qp:		QP from which to transmit
694  * @wqe:	Current WQE causing transmission
695  *
696  * TODO: Take into account real available sendspace on socket
697  *       to avoid header misalignment due to send pausing within
698  *       fpdu transmission
699  */
700 static void siw_prepare_fpdu(struct siw_qp *qp, struct siw_wqe *wqe)
701 {
702 	struct siw_iwarp_tx *c_tx = &qp->tx_ctx;
703 	int data_len;
704 
705 	c_tx->ctrl_len =
706 		iwarp_pktinfo[__rdmap_get_opcode(&c_tx->pkt.ctrl)].hdr_len;
707 	c_tx->ctrl_sent = 0;
708 
709 	/*
710 	 * Update target buffer offset if any
711 	 */
712 	if (!(c_tx->pkt.ctrl.ddp_rdmap_ctrl & DDP_FLAG_TAGGED))
713 		/* Untagged message */
714 		c_tx->pkt.c_untagged.ddp_mo = cpu_to_be32(wqe->processed);
715 	else /* Tagged message */
716 		c_tx->pkt.c_tagged.ddp_to =
717 			cpu_to_be64(wqe->sqe.raddr + wqe->processed);
718 
719 	data_len = wqe->bytes - wqe->processed;
720 	if (data_len + c_tx->ctrl_len + MPA_CRC_SIZE > c_tx->tcp_seglen) {
721 		/* Trim DDP payload to fit into current TCP segment */
722 		data_len = c_tx->tcp_seglen - (c_tx->ctrl_len + MPA_CRC_SIZE);
723 		c_tx->pkt.ctrl.ddp_rdmap_ctrl &= ~DDP_FLAG_LAST;
724 		c_tx->pad = 0;
725 	} else {
726 		c_tx->pkt.ctrl.ddp_rdmap_ctrl |= DDP_FLAG_LAST;
727 		c_tx->pad = -data_len & 0x3;
728 	}
729 	c_tx->bytes_unsent = data_len;
730 
731 	c_tx->pkt.ctrl.mpa_len =
732 		htons(c_tx->ctrl_len + data_len - MPA_HDR_SIZE);
733 
734 	/*
735 	 * Init MPA CRC computation
736 	 */
737 	if (c_tx->mpa_crc_hd) {
738 		crypto_shash_init(c_tx->mpa_crc_hd);
739 		crypto_shash_update(c_tx->mpa_crc_hd, (u8 *)&c_tx->pkt,
740 				    c_tx->ctrl_len);
741 		c_tx->do_crc = 1;
742 	}
743 }
744 
745 /*
746  * siw_check_sgl_tx()
747  *
748  * Check permissions for a list of SGE's (SGL).
749  * A successful check will have all memory referenced
750  * for transmission resolved and assigned to the WQE.
751  *
752  * @pd:		Protection Domain SGL should belong to
753  * @wqe:	WQE to be checked
754  * @perms:	requested access permissions
755  *
756  */
757 
758 static int siw_check_sgl_tx(struct ib_pd *pd, struct siw_wqe *wqe,
759 			    enum ib_access_flags perms)
760 {
761 	struct siw_sge *sge = &wqe->sqe.sge[0];
762 	int i, len, num_sge = wqe->sqe.num_sge;
763 
764 	if (unlikely(num_sge > SIW_MAX_SGE))
765 		return -EINVAL;
766 
767 	for (i = 0, len = 0; num_sge; num_sge--, i++, sge++) {
768 		/*
769 		 * rdma verbs: do not check stag for a zero length sge
770 		 */
771 		if (sge->length) {
772 			int rv = siw_check_sge(pd, sge, &wqe->mem[i], perms, 0,
773 					       sge->length);
774 
775 			if (unlikely(rv != E_ACCESS_OK))
776 				return rv;
777 		}
778 		len += sge->length;
779 	}
780 	return len;
781 }
782 
783 /*
784  * siw_qp_sq_proc_tx()
785  *
786  * Process one WQE which needs transmission on the wire.
787  */
788 static int siw_qp_sq_proc_tx(struct siw_qp *qp, struct siw_wqe *wqe)
789 {
790 	struct siw_iwarp_tx *c_tx = &qp->tx_ctx;
791 	struct socket *s = qp->attrs.sk;
792 	int rv = 0, burst_len = qp->tx_ctx.burst;
793 	enum rdmap_ecode ecode = RDMAP_ECODE_CATASTROPHIC_STREAM;
794 
795 	if (unlikely(wqe->wr_status == SIW_WR_IDLE))
796 		return 0;
797 
798 	if (!burst_len)
799 		burst_len = SQ_USER_MAXBURST;
800 
801 	if (wqe->wr_status == SIW_WR_QUEUED) {
802 		if (!(wqe->sqe.flags & SIW_WQE_INLINE)) {
803 			if (tx_type(wqe) == SIW_OP_READ_RESPONSE)
804 				wqe->sqe.num_sge = 1;
805 
806 			if (tx_type(wqe) != SIW_OP_READ &&
807 			    tx_type(wqe) != SIW_OP_READ_LOCAL_INV) {
808 				/*
809 				 * Reference memory to be tx'd w/o checking
810 				 * access for LOCAL_READ permission, since
811 				 * not defined in RDMA core.
812 				 */
813 				rv = siw_check_sgl_tx(qp->pd, wqe, 0);
814 				if (rv < 0) {
815 					if (tx_type(wqe) ==
816 					    SIW_OP_READ_RESPONSE)
817 						ecode = siw_rdmap_error(-rv);
818 					rv = -EINVAL;
819 					goto tx_error;
820 				}
821 				wqe->bytes = rv;
822 			} else {
823 				wqe->bytes = 0;
824 			}
825 		} else {
826 			wqe->bytes = wqe->sqe.sge[0].length;
827 			if (!rdma_is_kernel_res(&qp->base_qp.res)) {
828 				if (wqe->bytes > SIW_MAX_INLINE) {
829 					rv = -EINVAL;
830 					goto tx_error;
831 				}
832 				wqe->sqe.sge[0].laddr =
833 					(u64)(uintptr_t)&wqe->sqe.sge[1];
834 			}
835 		}
836 		wqe->wr_status = SIW_WR_INPROGRESS;
837 		wqe->processed = 0;
838 
839 		siw_update_tcpseg(c_tx, s);
840 
841 		rv = siw_qp_prepare_tx(c_tx);
842 		if (rv == PKT_FRAGMENTED) {
843 			c_tx->state = SIW_SEND_HDR;
844 			siw_prepare_fpdu(qp, wqe);
845 		} else if (rv == PKT_COMPLETE) {
846 			c_tx->state = SIW_SEND_SHORT_FPDU;
847 		} else {
848 			goto tx_error;
849 		}
850 	}
851 
852 next_segment:
853 	siw_dbg_qp(qp, "wr type %d, state %d, data %u, sent %u, id %llx\n",
854 		   tx_type(wqe), wqe->wr_status, wqe->bytes, wqe->processed,
855 		   wqe->sqe.id);
856 
857 	if (--burst_len == 0) {
858 		rv = -EINPROGRESS;
859 		goto tx_done;
860 	}
861 	if (c_tx->state == SIW_SEND_SHORT_FPDU) {
862 		enum siw_opcode tx_type = tx_type(wqe);
863 		unsigned int msg_flags;
864 
865 		if (siw_sq_empty(qp) || !siw_tcp_nagle || burst_len == 1)
866 			/*
867 			 * End current TCP segment, if SQ runs empty,
868 			 * or siw_tcp_nagle is not set, or we bail out
869 			 * soon due to no burst credit left.
870 			 */
871 			msg_flags = MSG_DONTWAIT;
872 		else
873 			msg_flags = MSG_DONTWAIT | MSG_MORE;
874 
875 		rv = siw_tx_ctrl(c_tx, s, msg_flags);
876 
877 		if (!rv && tx_type != SIW_OP_READ &&
878 		    tx_type != SIW_OP_READ_LOCAL_INV)
879 			wqe->processed = wqe->bytes;
880 
881 		goto tx_done;
882 
883 	} else {
884 		rv = siw_tx_hdt(c_tx, s);
885 	}
886 	if (!rv) {
887 		/*
888 		 * One segment sent. Processing completed if last
889 		 * segment, Do next segment otherwise.
890 		 */
891 		if (unlikely(c_tx->tx_suspend)) {
892 			/*
893 			 * Verbs, 6.4.: Try stopping sending after a full
894 			 * DDP segment if the connection goes down
895 			 * (== peer halfclose)
896 			 */
897 			rv = -ECONNABORTED;
898 			goto tx_done;
899 		}
900 		if (c_tx->pkt.ctrl.ddp_rdmap_ctrl & DDP_FLAG_LAST) {
901 			siw_dbg_qp(qp, "WQE completed\n");
902 			goto tx_done;
903 		}
904 		c_tx->state = SIW_SEND_HDR;
905 
906 		siw_update_tcpseg(c_tx, s);
907 
908 		siw_prepare_fpdu(qp, wqe);
909 		goto next_segment;
910 	}
911 tx_done:
912 	qp->tx_ctx.burst = burst_len;
913 	return rv;
914 
915 tx_error:
916 	if (ecode != RDMAP_ECODE_CATASTROPHIC_STREAM)
917 		siw_init_terminate(qp, TERM_ERROR_LAYER_RDMAP,
918 				   RDMAP_ETYPE_REMOTE_PROTECTION, ecode, 1);
919 	else
920 		siw_init_terminate(qp, TERM_ERROR_LAYER_RDMAP,
921 				   RDMAP_ETYPE_CATASTROPHIC,
922 				   RDMAP_ECODE_UNSPECIFIED, 1);
923 	return rv;
924 }
925 
926 static int siw_fastreg_mr(struct ib_pd *pd, struct siw_sqe *sqe)
927 {
928 	struct ib_mr *base_mr = (struct ib_mr *)(uintptr_t)sqe->base_mr;
929 	struct siw_device *sdev = to_siw_dev(pd->device);
930 	struct siw_mem *mem;
931 	int rv = 0;
932 
933 	siw_dbg_pd(pd, "STag 0x%08x\n", sqe->rkey);
934 
935 	if (unlikely(!base_mr)) {
936 		pr_warn("siw: fastreg: STag 0x%08x unknown\n", sqe->rkey);
937 		return -EINVAL;
938 	}
939 
940 	if (unlikely(base_mr->rkey >> 8 != sqe->rkey  >> 8)) {
941 		pr_warn("siw: fastreg: STag 0x%08x: bad MR\n", sqe->rkey);
942 		return -EINVAL;
943 	}
944 
945 	mem = siw_mem_id2obj(sdev, sqe->rkey  >> 8);
946 	if (unlikely(!mem)) {
947 		pr_warn("siw: fastreg: STag 0x%08x unknown\n", sqe->rkey);
948 		return -EINVAL;
949 	}
950 
951 	if (unlikely(mem->pd != pd)) {
952 		pr_warn("siw: fastreg: PD mismatch\n");
953 		rv = -EINVAL;
954 		goto out;
955 	}
956 	if (unlikely(mem->stag_valid)) {
957 		pr_warn("siw: fastreg: STag 0x%08x already valid\n", sqe->rkey);
958 		rv = -EINVAL;
959 		goto out;
960 	}
961 	/* Refresh STag since user may have changed key part */
962 	mem->stag = sqe->rkey;
963 	mem->perms = sqe->access;
964 
965 	siw_dbg_mem(mem, "STag 0x%08x now valid\n", sqe->rkey);
966 	mem->va = base_mr->iova;
967 	mem->stag_valid = 1;
968 out:
969 	siw_mem_put(mem);
970 	return rv;
971 }
972 
973 static int siw_qp_sq_proc_local(struct siw_qp *qp, struct siw_wqe *wqe)
974 {
975 	int rv;
976 
977 	switch (tx_type(wqe)) {
978 	case SIW_OP_REG_MR:
979 		rv = siw_fastreg_mr(qp->pd, &wqe->sqe);
980 		break;
981 
982 	case SIW_OP_INVAL_STAG:
983 		rv = siw_invalidate_stag(qp->pd, wqe->sqe.rkey);
984 		break;
985 
986 	default:
987 		rv = -EINVAL;
988 	}
989 	return rv;
990 }
991 
992 /*
993  * siw_qp_sq_process()
994  *
995  * Core TX path routine for RDMAP/DDP/MPA using a TCP kernel socket.
996  * Sends RDMAP payload for the current SQ WR @wqe of @qp in one or more
997  * MPA FPDUs, each containing a DDP segment.
998  *
999  * SQ processing may occur in user context as a result of posting
1000  * new WQE's or from siw_tx_thread context. Processing in
1001  * user context is limited to non-kernel verbs users.
1002  *
1003  * SQ processing may get paused anytime, possibly in the middle of a WR
1004  * or FPDU, if insufficient send space is available. SQ processing
1005  * gets resumed from siw_tx_thread, if send space becomes available again.
1006  *
1007  * Must be called with the QP state read-locked.
1008  *
1009  * Note:
1010  * An outbound RREQ can be satisfied by the corresponding RRESP
1011  * _before_ it gets assigned to the ORQ. This happens regularly
1012  * in RDMA READ via loopback case. Since both outbound RREQ and
1013  * inbound RRESP can be handled by the same CPU, locking the ORQ
1014  * is dead-lock prone and thus not an option. With that, the
1015  * RREQ gets assigned to the ORQ _before_ being sent - see
1016  * siw_activate_tx() - and pulled back in case of send failure.
1017  */
1018 int siw_qp_sq_process(struct siw_qp *qp)
1019 {
1020 	struct siw_wqe *wqe = tx_wqe(qp);
1021 	enum siw_opcode tx_type;
1022 	unsigned long flags;
1023 	int rv = 0;
1024 
1025 	siw_dbg_qp(qp, "enter for type %d\n", tx_type(wqe));
1026 
1027 next_wqe:
1028 	/*
1029 	 * Stop QP processing if SQ state changed
1030 	 */
1031 	if (unlikely(qp->tx_ctx.tx_suspend)) {
1032 		siw_dbg_qp(qp, "tx suspended\n");
1033 		goto done;
1034 	}
1035 	tx_type = tx_type(wqe);
1036 
1037 	if (tx_type <= SIW_OP_READ_RESPONSE)
1038 		rv = siw_qp_sq_proc_tx(qp, wqe);
1039 	else
1040 		rv = siw_qp_sq_proc_local(qp, wqe);
1041 
1042 	if (!rv) {
1043 		/*
1044 		 * WQE processing done
1045 		 */
1046 		switch (tx_type) {
1047 		case SIW_OP_SEND:
1048 		case SIW_OP_SEND_REMOTE_INV:
1049 		case SIW_OP_WRITE:
1050 			siw_wqe_put_mem(wqe, tx_type);
1051 			fallthrough;
1052 
1053 		case SIW_OP_INVAL_STAG:
1054 		case SIW_OP_REG_MR:
1055 			if (tx_flags(wqe) & SIW_WQE_SIGNALLED)
1056 				siw_sqe_complete(qp, &wqe->sqe, wqe->bytes,
1057 						 SIW_WC_SUCCESS);
1058 			break;
1059 
1060 		case SIW_OP_READ:
1061 		case SIW_OP_READ_LOCAL_INV:
1062 			/*
1063 			 * already enqueued to ORQ queue
1064 			 */
1065 			break;
1066 
1067 		case SIW_OP_READ_RESPONSE:
1068 			siw_wqe_put_mem(wqe, tx_type);
1069 			break;
1070 
1071 		default:
1072 			WARN(1, "undefined WQE type %d\n", tx_type);
1073 			rv = -EINVAL;
1074 			goto done;
1075 		}
1076 
1077 		spin_lock_irqsave(&qp->sq_lock, flags);
1078 		wqe->wr_status = SIW_WR_IDLE;
1079 		rv = siw_activate_tx(qp);
1080 		spin_unlock_irqrestore(&qp->sq_lock, flags);
1081 
1082 		if (rv <= 0)
1083 			goto done;
1084 
1085 		goto next_wqe;
1086 
1087 	} else if (rv == -EAGAIN) {
1088 		siw_dbg_qp(qp, "sq paused: hd/tr %d of %d, data %d\n",
1089 			   qp->tx_ctx.ctrl_sent, qp->tx_ctx.ctrl_len,
1090 			   qp->tx_ctx.bytes_unsent);
1091 		rv = 0;
1092 		goto done;
1093 	} else if (rv == -EINPROGRESS) {
1094 		rv = siw_sq_start(qp);
1095 		goto done;
1096 	} else {
1097 		/*
1098 		 * WQE processing failed.
1099 		 * Verbs 8.3.2:
1100 		 * o It turns any WQE into a signalled WQE.
1101 		 * o Local catastrophic error must be surfaced
1102 		 * o QP must be moved into Terminate state: done by code
1103 		 *   doing socket state change processing
1104 		 *
1105 		 * o TODO: Termination message must be sent.
1106 		 * o TODO: Implement more precise work completion errors,
1107 		 *         see enum ib_wc_status in ib_verbs.h
1108 		 */
1109 		siw_dbg_qp(qp, "wqe type %d processing failed: %d\n",
1110 			   tx_type(wqe), rv);
1111 
1112 		spin_lock_irqsave(&qp->sq_lock, flags);
1113 		/*
1114 		 * RREQ may have already been completed by inbound RRESP!
1115 		 */
1116 		if ((tx_type == SIW_OP_READ ||
1117 		     tx_type == SIW_OP_READ_LOCAL_INV) && qp->attrs.orq_size) {
1118 			/* Cleanup pending entry in ORQ */
1119 			qp->orq_put--;
1120 			qp->orq[qp->orq_put % qp->attrs.orq_size].flags = 0;
1121 		}
1122 		spin_unlock_irqrestore(&qp->sq_lock, flags);
1123 		/*
1124 		 * immediately suspends further TX processing
1125 		 */
1126 		if (!qp->tx_ctx.tx_suspend)
1127 			siw_qp_cm_drop(qp, 0);
1128 
1129 		switch (tx_type) {
1130 		case SIW_OP_SEND:
1131 		case SIW_OP_SEND_REMOTE_INV:
1132 		case SIW_OP_SEND_WITH_IMM:
1133 		case SIW_OP_WRITE:
1134 		case SIW_OP_READ:
1135 		case SIW_OP_READ_LOCAL_INV:
1136 			siw_wqe_put_mem(wqe, tx_type);
1137 			fallthrough;
1138 
1139 		case SIW_OP_INVAL_STAG:
1140 		case SIW_OP_REG_MR:
1141 			siw_sqe_complete(qp, &wqe->sqe, wqe->bytes,
1142 					 SIW_WC_LOC_QP_OP_ERR);
1143 
1144 			siw_qp_event(qp, IB_EVENT_QP_FATAL);
1145 
1146 			break;
1147 
1148 		case SIW_OP_READ_RESPONSE:
1149 			siw_dbg_qp(qp, "proc. read.response failed: %d\n", rv);
1150 
1151 			siw_qp_event(qp, IB_EVENT_QP_REQ_ERR);
1152 
1153 			siw_wqe_put_mem(wqe, SIW_OP_READ_RESPONSE);
1154 
1155 			break;
1156 
1157 		default:
1158 			WARN(1, "undefined WQE type %d\n", tx_type);
1159 			rv = -EINVAL;
1160 		}
1161 		wqe->wr_status = SIW_WR_IDLE;
1162 	}
1163 done:
1164 	return rv;
1165 }
1166 
1167 static void siw_sq_resume(struct siw_qp *qp)
1168 {
1169 	if (down_read_trylock(&qp->state_lock)) {
1170 		if (likely(qp->attrs.state == SIW_QP_STATE_RTS &&
1171 			   !qp->tx_ctx.tx_suspend)) {
1172 			int rv = siw_qp_sq_process(qp);
1173 
1174 			up_read(&qp->state_lock);
1175 
1176 			if (unlikely(rv < 0)) {
1177 				siw_dbg_qp(qp, "SQ task failed: err %d\n", rv);
1178 
1179 				if (!qp->tx_ctx.tx_suspend)
1180 					siw_qp_cm_drop(qp, 0);
1181 			}
1182 		} else {
1183 			up_read(&qp->state_lock);
1184 		}
1185 	} else {
1186 		siw_dbg_qp(qp, "Resume SQ while QP locked\n");
1187 	}
1188 	siw_qp_put(qp);
1189 }
1190 
1191 struct tx_task_t {
1192 	struct llist_head active;
1193 	wait_queue_head_t waiting;
1194 };
1195 
1196 static DEFINE_PER_CPU(struct tx_task_t, siw_tx_task_g);
1197 
1198 int siw_create_tx_threads(void)
1199 {
1200 	int cpu, assigned = 0;
1201 
1202 	for_each_online_cpu(cpu) {
1203 		struct tx_task_t *tx_task;
1204 
1205 		/* Skip HT cores */
1206 		if (cpu % cpumask_weight(topology_sibling_cpumask(cpu)))
1207 			continue;
1208 
1209 		tx_task = &per_cpu(siw_tx_task_g, cpu);
1210 		init_llist_head(&tx_task->active);
1211 		init_waitqueue_head(&tx_task->waiting);
1212 
1213 		siw_tx_thread[cpu] =
1214 			kthread_run_on_cpu(siw_run_sq,
1215 					   (unsigned long *)(long)cpu,
1216 					   cpu, "siw_tx/%u");
1217 		if (IS_ERR(siw_tx_thread[cpu])) {
1218 			siw_tx_thread[cpu] = NULL;
1219 			continue;
1220 		}
1221 		assigned++;
1222 	}
1223 	return assigned;
1224 }
1225 
1226 void siw_stop_tx_threads(void)
1227 {
1228 	int cpu;
1229 
1230 	for_each_possible_cpu(cpu) {
1231 		if (siw_tx_thread[cpu]) {
1232 			kthread_stop(siw_tx_thread[cpu]);
1233 			wake_up(&per_cpu(siw_tx_task_g, cpu).waiting);
1234 			siw_tx_thread[cpu] = NULL;
1235 		}
1236 	}
1237 }
1238 
1239 int siw_run_sq(void *data)
1240 {
1241 	const int nr_cpu = (unsigned int)(long)data;
1242 	struct llist_node *active;
1243 	struct siw_qp *qp;
1244 	struct tx_task_t *tx_task = &per_cpu(siw_tx_task_g, nr_cpu);
1245 
1246 	while (1) {
1247 		struct llist_node *fifo_list = NULL;
1248 
1249 		wait_event_interruptible(tx_task->waiting,
1250 					 !llist_empty(&tx_task->active) ||
1251 						 kthread_should_stop());
1252 
1253 		if (kthread_should_stop())
1254 			break;
1255 
1256 		active = llist_del_all(&tx_task->active);
1257 		/*
1258 		 * llist_del_all returns a list with newest entry first.
1259 		 * Re-order list for fairness among QP's.
1260 		 */
1261 		fifo_list = llist_reverse_order(active);
1262 		while (fifo_list) {
1263 			qp = container_of(fifo_list, struct siw_qp, tx_list);
1264 			fifo_list = llist_next(fifo_list);
1265 			qp->tx_list.next = NULL;
1266 
1267 			siw_sq_resume(qp);
1268 		}
1269 	}
1270 	active = llist_del_all(&tx_task->active);
1271 	if (active) {
1272 		llist_for_each_entry(qp, active, tx_list) {
1273 			qp->tx_list.next = NULL;
1274 			siw_sq_resume(qp);
1275 		}
1276 	}
1277 	return 0;
1278 }
1279 
1280 int siw_sq_start(struct siw_qp *qp)
1281 {
1282 	if (tx_wqe(qp)->wr_status == SIW_WR_IDLE)
1283 		return 0;
1284 
1285 	if (unlikely(!cpu_online(qp->tx_cpu))) {
1286 		siw_put_tx_cpu(qp->tx_cpu);
1287 		qp->tx_cpu = siw_get_tx_cpu(qp->sdev);
1288 		if (qp->tx_cpu < 0) {
1289 			pr_warn("siw: no tx cpu available\n");
1290 
1291 			return -EIO;
1292 		}
1293 	}
1294 	siw_qp_get(qp);
1295 
1296 	llist_add(&qp->tx_list, &per_cpu(siw_tx_task_g, qp->tx_cpu).active);
1297 
1298 	wake_up(&per_cpu(siw_tx_task_g, qp->tx_cpu).waiting);
1299 
1300 	return 0;
1301 }
1302