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((void *)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_local_page(p);
80 
81 			if (likely(PAGE_SIZE - off >= bytes)) {
82 				memcpy(paddr, buffer + off, bytes);
83 			} else {
84 				unsigned long part = bytes - (PAGE_SIZE - off);
85 
86 				memcpy(paddr, buffer + off, part);
87 				kunmap_local(buffer);
88 
89 				if (!mem->is_pbl)
90 					p = siw_get_upage(mem->umem,
91 							  sge->laddr + part);
92 				else
93 					p = siw_get_pblpage(mem,
94 							    sge->laddr + part,
95 							    &pbl_idx);
96 				if (unlikely(!p))
97 					return -EFAULT;
98 
99 				buffer = kmap_local_page(p);
100 				memcpy(paddr + part, buffer, bytes - part);
101 			}
102 			kunmap_local(buffer);
103 		}
104 	}
105 	return (int)bytes;
106 }
107 
108 #define PKT_FRAGMENTED 1
109 #define PKT_COMPLETE 0
110 
111 /*
112  * siw_qp_prepare_tx()
113  *
114  * Prepare tx state for sending out one fpdu. Builds complete pkt
115  * if no user data or only immediate data are present.
116  *
117  * returns PKT_COMPLETE if complete pkt built, PKT_FRAGMENTED otherwise.
118  */
119 static int siw_qp_prepare_tx(struct siw_iwarp_tx *c_tx)
120 {
121 	struct siw_wqe *wqe = &c_tx->wqe_active;
122 	char *crc = NULL;
123 	int data = 0;
124 
125 	switch (tx_type(wqe)) {
126 	case SIW_OP_READ:
127 	case SIW_OP_READ_LOCAL_INV:
128 		memcpy(&c_tx->pkt.ctrl,
129 		       &iwarp_pktinfo[RDMAP_RDMA_READ_REQ].ctrl,
130 		       sizeof(struct iwarp_ctrl));
131 
132 		c_tx->pkt.rreq.rsvd = 0;
133 		c_tx->pkt.rreq.ddp_qn = htonl(RDMAP_UNTAGGED_QN_RDMA_READ);
134 		c_tx->pkt.rreq.ddp_msn =
135 			htonl(++c_tx->ddp_msn[RDMAP_UNTAGGED_QN_RDMA_READ]);
136 		c_tx->pkt.rreq.ddp_mo = 0;
137 		c_tx->pkt.rreq.sink_stag = htonl(wqe->sqe.sge[0].lkey);
138 		c_tx->pkt.rreq.sink_to =
139 			cpu_to_be64(wqe->sqe.sge[0].laddr);
140 		c_tx->pkt.rreq.source_stag = htonl(wqe->sqe.rkey);
141 		c_tx->pkt.rreq.source_to = cpu_to_be64(wqe->sqe.raddr);
142 		c_tx->pkt.rreq.read_size = htonl(wqe->sqe.sge[0].length);
143 
144 		c_tx->ctrl_len = sizeof(struct iwarp_rdma_rreq);
145 		crc = (char *)&c_tx->pkt.rreq_pkt.crc;
146 		break;
147 
148 	case SIW_OP_SEND:
149 		if (tx_flags(wqe) & SIW_WQE_SOLICITED)
150 			memcpy(&c_tx->pkt.ctrl,
151 			       &iwarp_pktinfo[RDMAP_SEND_SE].ctrl,
152 			       sizeof(struct iwarp_ctrl));
153 		else
154 			memcpy(&c_tx->pkt.ctrl, &iwarp_pktinfo[RDMAP_SEND].ctrl,
155 			       sizeof(struct iwarp_ctrl));
156 
157 		c_tx->pkt.send.ddp_qn = RDMAP_UNTAGGED_QN_SEND;
158 		c_tx->pkt.send.ddp_msn =
159 			htonl(++c_tx->ddp_msn[RDMAP_UNTAGGED_QN_SEND]);
160 		c_tx->pkt.send.ddp_mo = 0;
161 
162 		c_tx->pkt.send_inv.inval_stag = 0;
163 
164 		c_tx->ctrl_len = sizeof(struct iwarp_send);
165 
166 		crc = (char *)&c_tx->pkt.send_pkt.crc;
167 		data = siw_try_1seg(c_tx, crc);
168 		break;
169 
170 	case SIW_OP_SEND_REMOTE_INV:
171 		if (tx_flags(wqe) & SIW_WQE_SOLICITED)
172 			memcpy(&c_tx->pkt.ctrl,
173 			       &iwarp_pktinfo[RDMAP_SEND_SE_INVAL].ctrl,
174 			       sizeof(struct iwarp_ctrl));
175 		else
176 			memcpy(&c_tx->pkt.ctrl,
177 			       &iwarp_pktinfo[RDMAP_SEND_INVAL].ctrl,
178 			       sizeof(struct iwarp_ctrl));
179 
180 		c_tx->pkt.send.ddp_qn = RDMAP_UNTAGGED_QN_SEND;
181 		c_tx->pkt.send.ddp_msn =
182 			htonl(++c_tx->ddp_msn[RDMAP_UNTAGGED_QN_SEND]);
183 		c_tx->pkt.send.ddp_mo = 0;
184 
185 		c_tx->pkt.send_inv.inval_stag = cpu_to_be32(wqe->sqe.rkey);
186 
187 		c_tx->ctrl_len = sizeof(struct iwarp_send_inv);
188 
189 		crc = (char *)&c_tx->pkt.send_pkt.crc;
190 		data = siw_try_1seg(c_tx, crc);
191 		break;
192 
193 	case SIW_OP_WRITE:
194 		memcpy(&c_tx->pkt.ctrl, &iwarp_pktinfo[RDMAP_RDMA_WRITE].ctrl,
195 		       sizeof(struct iwarp_ctrl));
196 
197 		c_tx->pkt.rwrite.sink_stag = htonl(wqe->sqe.rkey);
198 		c_tx->pkt.rwrite.sink_to = cpu_to_be64(wqe->sqe.raddr);
199 		c_tx->ctrl_len = sizeof(struct iwarp_rdma_write);
200 
201 		crc = (char *)&c_tx->pkt.write_pkt.crc;
202 		data = siw_try_1seg(c_tx, crc);
203 		break;
204 
205 	case SIW_OP_READ_RESPONSE:
206 		memcpy(&c_tx->pkt.ctrl,
207 		       &iwarp_pktinfo[RDMAP_RDMA_READ_RESP].ctrl,
208 		       sizeof(struct iwarp_ctrl));
209 
210 		/* NBO */
211 		c_tx->pkt.rresp.sink_stag = cpu_to_be32(wqe->sqe.rkey);
212 		c_tx->pkt.rresp.sink_to = cpu_to_be64(wqe->sqe.raddr);
213 
214 		c_tx->ctrl_len = sizeof(struct iwarp_rdma_rresp);
215 
216 		crc = (char *)&c_tx->pkt.write_pkt.crc;
217 		data = siw_try_1seg(c_tx, crc);
218 		break;
219 
220 	default:
221 		siw_dbg_qp(tx_qp(c_tx), "stale wqe type %d\n", tx_type(wqe));
222 		return -EOPNOTSUPP;
223 	}
224 	if (unlikely(data < 0))
225 		return data;
226 
227 	c_tx->ctrl_sent = 0;
228 
229 	if (data <= MAX_HDR_INLINE) {
230 		if (data) {
231 			wqe->processed = data;
232 
233 			c_tx->pkt.ctrl.mpa_len =
234 				htons(c_tx->ctrl_len + data - MPA_HDR_SIZE);
235 
236 			/* Add pad, if needed */
237 			data += -(int)data & 0x3;
238 			/* advance CRC location after payload */
239 			crc += data;
240 			c_tx->ctrl_len += data;
241 
242 			if (!(c_tx->pkt.ctrl.ddp_rdmap_ctrl & DDP_FLAG_TAGGED))
243 				c_tx->pkt.c_untagged.ddp_mo = 0;
244 			else
245 				c_tx->pkt.c_tagged.ddp_to =
246 					cpu_to_be64(wqe->sqe.raddr);
247 		}
248 
249 		*(u32 *)crc = 0;
250 		/*
251 		 * Do complete CRC if enabled and short packet
252 		 */
253 		if (c_tx->mpa_crc_hd) {
254 			crypto_shash_init(c_tx->mpa_crc_hd);
255 			if (crypto_shash_update(c_tx->mpa_crc_hd,
256 						(u8 *)&c_tx->pkt,
257 						c_tx->ctrl_len))
258 				return -EINVAL;
259 			crypto_shash_final(c_tx->mpa_crc_hd, (u8 *)crc);
260 		}
261 		c_tx->ctrl_len += MPA_CRC_SIZE;
262 
263 		return PKT_COMPLETE;
264 	}
265 	c_tx->ctrl_len += MPA_CRC_SIZE;
266 	c_tx->sge_idx = 0;
267 	c_tx->sge_off = 0;
268 	c_tx->pbl_idx = 0;
269 
270 	/*
271 	 * Allow direct sending out of user buffer if WR is non signalled
272 	 * and payload is over threshold.
273 	 * Per RDMA verbs, the application should not change the send buffer
274 	 * until the work completed. In iWarp, work completion is only
275 	 * local delivery to TCP. TCP may reuse the buffer for
276 	 * retransmission. Changing unsent data also breaks the CRC,
277 	 * if applied.
278 	 */
279 	if (c_tx->zcopy_tx && wqe->bytes >= SENDPAGE_THRESH &&
280 	    !(tx_flags(wqe) & SIW_WQE_SIGNALLED))
281 		c_tx->use_sendpage = 1;
282 	else
283 		c_tx->use_sendpage = 0;
284 
285 	return PKT_FRAGMENTED;
286 }
287 
288 /*
289  * Send out one complete control type FPDU, or header of FPDU carrying
290  * data. Used for fixed sized packets like Read.Requests or zero length
291  * SENDs, WRITEs, READ.Responses, or header only.
292  */
293 static int siw_tx_ctrl(struct siw_iwarp_tx *c_tx, struct socket *s,
294 			      int flags)
295 {
296 	struct msghdr msg = { .msg_flags = flags };
297 	struct kvec iov = { .iov_base =
298 				    (char *)&c_tx->pkt.ctrl + c_tx->ctrl_sent,
299 			    .iov_len = c_tx->ctrl_len - c_tx->ctrl_sent };
300 
301 	int rv = kernel_sendmsg(s, &msg, &iov, 1,
302 				c_tx->ctrl_len - c_tx->ctrl_sent);
303 
304 	if (rv >= 0) {
305 		c_tx->ctrl_sent += rv;
306 
307 		if (c_tx->ctrl_sent == c_tx->ctrl_len)
308 			rv = 0;
309 		else
310 			rv = -EAGAIN;
311 	}
312 	return rv;
313 }
314 
315 /*
316  * 0copy TCP transmit interface: Use do_tcp_sendpages.
317  *
318  * Using sendpage to push page by page appears to be less efficient
319  * than using sendmsg, even if data are copied.
320  *
321  * A general performance limitation might be the extra four bytes
322  * trailer checksum segment to be pushed after user data.
323  */
324 static int siw_tcp_sendpages(struct socket *s, struct page **page, int offset,
325 			     size_t size)
326 {
327 	struct sock *sk = s->sk;
328 	int i = 0, rv = 0, sent = 0,
329 	    flags = MSG_MORE | MSG_DONTWAIT | MSG_SENDPAGE_NOTLAST;
330 
331 	while (size) {
332 		size_t bytes = min_t(size_t, PAGE_SIZE - offset, size);
333 
334 		if (size + offset <= PAGE_SIZE)
335 			flags = MSG_MORE | MSG_DONTWAIT;
336 
337 		tcp_rate_check_app_limited(sk);
338 try_page_again:
339 		lock_sock(sk);
340 		rv = do_tcp_sendpages(sk, page[i], offset, bytes, flags);
341 		release_sock(sk);
342 
343 		if (rv > 0) {
344 			size -= rv;
345 			sent += rv;
346 			if (rv != bytes) {
347 				offset += rv;
348 				bytes -= rv;
349 				goto try_page_again;
350 			}
351 			offset = 0;
352 		} else {
353 			if (rv == -EAGAIN || rv == 0)
354 				break;
355 			return rv;
356 		}
357 		i++;
358 	}
359 	return sent;
360 }
361 
362 /*
363  * siw_0copy_tx()
364  *
365  * Pushes list of pages to TCP socket. If pages from multiple
366  * SGE's, all referenced pages of each SGE are pushed in one
367  * shot.
368  */
369 static int siw_0copy_tx(struct socket *s, struct page **page,
370 			struct siw_sge *sge, unsigned int offset,
371 			unsigned int size)
372 {
373 	int i = 0, sent = 0, rv;
374 	int sge_bytes = min(sge->length - offset, size);
375 
376 	offset = (sge->laddr + offset) & ~PAGE_MASK;
377 
378 	while (sent != size) {
379 		rv = siw_tcp_sendpages(s, &page[i], offset, sge_bytes);
380 		if (rv >= 0) {
381 			sent += rv;
382 			if (size == sent || sge_bytes > rv)
383 				break;
384 
385 			i += PAGE_ALIGN(sge_bytes + offset) >> PAGE_SHIFT;
386 			sge++;
387 			sge_bytes = min(sge->length, size - sent);
388 			offset = sge->laddr & ~PAGE_MASK;
389 		} else {
390 			sent = rv;
391 			break;
392 		}
393 	}
394 	return sent;
395 }
396 
397 #define MAX_TRAILER (MPA_CRC_SIZE + 4)
398 
399 static void siw_unmap_pages(struct kvec *iov, unsigned long kmap_mask, int len)
400 {
401 	int i;
402 
403 	/*
404 	 * Work backwards through the array to honor the kmap_local_page()
405 	 * ordering requirements.
406 	 */
407 	for (i = (len-1); i >= 0; i--) {
408 		if (kmap_mask & BIT(i)) {
409 			unsigned long addr = (unsigned long)iov[i].iov_base;
410 
411 			kunmap_local((void *)(addr & PAGE_MASK));
412 		}
413 	}
414 }
415 
416 /*
417  * siw_tx_hdt() tries to push a complete packet to TCP where all
418  * packet fragments are referenced by the elements of one iovec.
419  * For the data portion, each involved page must be referenced by
420  * one extra element. All sge's data can be non-aligned to page
421  * boundaries. Two more elements are referencing iWARP header
422  * and trailer:
423  * MAX_ARRAY = 64KB/PAGE_SIZE + 1 + (2 * (SIW_MAX_SGE - 1) + HDR + TRL
424  */
425 #define MAX_ARRAY ((0xffff / PAGE_SIZE) + 1 + (2 * (SIW_MAX_SGE - 1) + 2))
426 
427 /*
428  * Write out iov referencing hdr, data and trailer of current FPDU.
429  * Update transmit state dependent on write return status
430  */
431 static int siw_tx_hdt(struct siw_iwarp_tx *c_tx, struct socket *s)
432 {
433 	struct siw_wqe *wqe = &c_tx->wqe_active;
434 	struct siw_sge *sge = &wqe->sqe.sge[c_tx->sge_idx];
435 	struct kvec iov[MAX_ARRAY];
436 	struct page *page_array[MAX_ARRAY];
437 	struct msghdr msg = { .msg_flags = MSG_DONTWAIT | MSG_EOR };
438 
439 	int seg = 0, do_crc = c_tx->do_crc, is_kva = 0, rv;
440 	unsigned int data_len = c_tx->bytes_unsent, hdr_len = 0, trl_len = 0,
441 		     sge_off = c_tx->sge_off, sge_idx = c_tx->sge_idx,
442 		     pbl_idx = c_tx->pbl_idx;
443 	unsigned long kmap_mask = 0L;
444 
445 	if (c_tx->state == SIW_SEND_HDR) {
446 		if (c_tx->use_sendpage) {
447 			rv = siw_tx_ctrl(c_tx, s, MSG_DONTWAIT | MSG_MORE);
448 			if (rv)
449 				goto done;
450 
451 			c_tx->state = SIW_SEND_DATA;
452 		} else {
453 			iov[0].iov_base =
454 				(char *)&c_tx->pkt.ctrl + c_tx->ctrl_sent;
455 			iov[0].iov_len = hdr_len =
456 				c_tx->ctrl_len - c_tx->ctrl_sent;
457 			seg = 1;
458 		}
459 	}
460 
461 	wqe->processed += data_len;
462 
463 	while (data_len) { /* walk the list of SGE's */
464 		unsigned int sge_len = min(sge->length - sge_off, data_len);
465 		unsigned int fp_off = (sge->laddr + sge_off) & ~PAGE_MASK;
466 		struct siw_mem *mem;
467 
468 		if (!(tx_flags(wqe) & SIW_WQE_INLINE)) {
469 			mem = wqe->mem[sge_idx];
470 			is_kva = mem->mem_obj == NULL ? 1 : 0;
471 		} else {
472 			is_kva = 1;
473 		}
474 		if (is_kva && !c_tx->use_sendpage) {
475 			/*
476 			 * tx from kernel virtual address: either inline data
477 			 * or memory region with assigned kernel buffer
478 			 */
479 			iov[seg].iov_base =
480 				(void *)(uintptr_t)(sge->laddr + sge_off);
481 			iov[seg].iov_len = sge_len;
482 
483 			if (do_crc)
484 				crypto_shash_update(c_tx->mpa_crc_hd,
485 						    iov[seg].iov_base,
486 						    sge_len);
487 			sge_off += sge_len;
488 			data_len -= sge_len;
489 			seg++;
490 			goto sge_done;
491 		}
492 
493 		while (sge_len) {
494 			size_t plen = min((int)PAGE_SIZE - fp_off, sge_len);
495 			void *kaddr;
496 
497 			if (!is_kva) {
498 				struct page *p;
499 
500 				if (mem->is_pbl)
501 					p = siw_get_pblpage(
502 						mem, sge->laddr + sge_off,
503 						&pbl_idx);
504 				else
505 					p = siw_get_upage(mem->umem,
506 							  sge->laddr + sge_off);
507 				if (unlikely(!p)) {
508 					siw_unmap_pages(iov, kmap_mask, seg);
509 					wqe->processed -= c_tx->bytes_unsent;
510 					rv = -EFAULT;
511 					goto done_crc;
512 				}
513 				page_array[seg] = p;
514 
515 				if (!c_tx->use_sendpage) {
516 					void *kaddr = kmap_local_page(p);
517 
518 					/* Remember for later kunmap() */
519 					kmap_mask |= BIT(seg);
520 					iov[seg].iov_base = kaddr + fp_off;
521 					iov[seg].iov_len = plen;
522 
523 					if (do_crc)
524 						crypto_shash_update(
525 							c_tx->mpa_crc_hd,
526 							iov[seg].iov_base,
527 							plen);
528 				} else if (do_crc) {
529 					kaddr = kmap_local_page(p);
530 					crypto_shash_update(c_tx->mpa_crc_hd,
531 							    kaddr + fp_off,
532 							    plen);
533 					kunmap_local(kaddr);
534 				}
535 			} else {
536 				/*
537 				 * Cast to an uintptr_t to preserve all 64 bits
538 				 * in sge->laddr.
539 				 */
540 				uintptr_t va = (uintptr_t)(sge->laddr + sge_off);
541 
542 				/*
543 				 * virt_to_page() takes a (void *) pointer
544 				 * so cast to a (void *) meaning it will be 64
545 				 * bits on a 64 bit platform and 32 bits on a
546 				 * 32 bit platform.
547 				 */
548 				page_array[seg] = virt_to_page((void *)(va & PAGE_MASK));
549 				if (do_crc)
550 					crypto_shash_update(
551 						c_tx->mpa_crc_hd,
552 						(void *)va,
553 						plen);
554 			}
555 
556 			sge_len -= plen;
557 			sge_off += plen;
558 			data_len -= plen;
559 			fp_off = 0;
560 
561 			if (++seg > (int)MAX_ARRAY) {
562 				siw_dbg_qp(tx_qp(c_tx), "to many fragments\n");
563 				siw_unmap_pages(iov, kmap_mask, seg-1);
564 				wqe->processed -= c_tx->bytes_unsent;
565 				rv = -EMSGSIZE;
566 				goto done_crc;
567 			}
568 		}
569 sge_done:
570 		/* Update SGE variables at end of SGE */
571 		if (sge_off == sge->length &&
572 		    (data_len != 0 || wqe->processed < wqe->bytes)) {
573 			sge_idx++;
574 			sge++;
575 			sge_off = 0;
576 		}
577 	}
578 	/* trailer */
579 	if (likely(c_tx->state != SIW_SEND_TRAILER)) {
580 		iov[seg].iov_base = &c_tx->trailer.pad[4 - c_tx->pad];
581 		iov[seg].iov_len = trl_len = MAX_TRAILER - (4 - c_tx->pad);
582 	} else {
583 		iov[seg].iov_base = &c_tx->trailer.pad[c_tx->ctrl_sent];
584 		iov[seg].iov_len = trl_len = MAX_TRAILER - c_tx->ctrl_sent;
585 	}
586 
587 	if (c_tx->pad) {
588 		*(u32 *)c_tx->trailer.pad = 0;
589 		if (do_crc)
590 			crypto_shash_update(c_tx->mpa_crc_hd,
591 				(u8 *)&c_tx->trailer.crc - c_tx->pad,
592 				c_tx->pad);
593 	}
594 	if (!c_tx->mpa_crc_hd)
595 		c_tx->trailer.crc = 0;
596 	else if (do_crc)
597 		crypto_shash_final(c_tx->mpa_crc_hd, (u8 *)&c_tx->trailer.crc);
598 
599 	data_len = c_tx->bytes_unsent;
600 
601 	if (c_tx->use_sendpage) {
602 		rv = siw_0copy_tx(s, page_array, &wqe->sqe.sge[c_tx->sge_idx],
603 				  c_tx->sge_off, data_len);
604 		if (rv == data_len) {
605 			rv = kernel_sendmsg(s, &msg, &iov[seg], 1, trl_len);
606 			if (rv > 0)
607 				rv += data_len;
608 			else
609 				rv = data_len;
610 		}
611 	} else {
612 		rv = kernel_sendmsg(s, &msg, iov, seg + 1,
613 				    hdr_len + data_len + trl_len);
614 		siw_unmap_pages(iov, kmap_mask, seg);
615 	}
616 	if (rv < (int)hdr_len) {
617 		/* Not even complete hdr pushed or negative rv */
618 		wqe->processed -= data_len;
619 		if (rv >= 0) {
620 			c_tx->ctrl_sent += rv;
621 			rv = -EAGAIN;
622 		}
623 		goto done_crc;
624 	}
625 	rv -= hdr_len;
626 
627 	if (rv >= (int)data_len) {
628 		/* all user data pushed to TCP or no data to push */
629 		if (data_len > 0 && wqe->processed < wqe->bytes) {
630 			/* Save the current state for next tx */
631 			c_tx->sge_idx = sge_idx;
632 			c_tx->sge_off = sge_off;
633 			c_tx->pbl_idx = pbl_idx;
634 		}
635 		rv -= data_len;
636 
637 		if (rv == trl_len) /* all pushed */
638 			rv = 0;
639 		else {
640 			c_tx->state = SIW_SEND_TRAILER;
641 			c_tx->ctrl_len = MAX_TRAILER;
642 			c_tx->ctrl_sent = rv + 4 - c_tx->pad;
643 			c_tx->bytes_unsent = 0;
644 			rv = -EAGAIN;
645 		}
646 
647 	} else if (data_len > 0) {
648 		/* Maybe some user data pushed to TCP */
649 		c_tx->state = SIW_SEND_DATA;
650 		wqe->processed -= data_len - rv;
651 
652 		if (rv) {
653 			/*
654 			 * Some bytes out. Recompute tx state based
655 			 * on old state and bytes pushed
656 			 */
657 			unsigned int sge_unsent;
658 
659 			c_tx->bytes_unsent -= rv;
660 			sge = &wqe->sqe.sge[c_tx->sge_idx];
661 			sge_unsent = sge->length - c_tx->sge_off;
662 
663 			while (sge_unsent <= rv) {
664 				rv -= sge_unsent;
665 				c_tx->sge_idx++;
666 				c_tx->sge_off = 0;
667 				sge++;
668 				sge_unsent = sge->length;
669 			}
670 			c_tx->sge_off += rv;
671 		}
672 		rv = -EAGAIN;
673 	}
674 done_crc:
675 	c_tx->do_crc = 0;
676 done:
677 	return rv;
678 }
679 
680 static void siw_update_tcpseg(struct siw_iwarp_tx *c_tx,
681 				     struct socket *s)
682 {
683 	struct tcp_sock *tp = tcp_sk(s->sk);
684 
685 	if (tp->gso_segs) {
686 		if (c_tx->gso_seg_limit == 0)
687 			c_tx->tcp_seglen = tp->mss_cache * tp->gso_segs;
688 		else
689 			c_tx->tcp_seglen =
690 				tp->mss_cache *
691 				min_t(u16, c_tx->gso_seg_limit, tp->gso_segs);
692 	} else {
693 		c_tx->tcp_seglen = tp->mss_cache;
694 	}
695 	/* Loopback may give odd numbers */
696 	c_tx->tcp_seglen &= 0xfffffff8;
697 }
698 
699 /*
700  * siw_prepare_fpdu()
701  *
702  * Prepares transmit context to send out one FPDU if FPDU will contain
703  * user data and user data are not immediate data.
704  * Computes maximum FPDU length to fill up TCP MSS if possible.
705  *
706  * @qp:		QP from which to transmit
707  * @wqe:	Current WQE causing transmission
708  *
709  * TODO: Take into account real available sendspace on socket
710  *       to avoid header misalignment due to send pausing within
711  *       fpdu transmission
712  */
713 static void siw_prepare_fpdu(struct siw_qp *qp, struct siw_wqe *wqe)
714 {
715 	struct siw_iwarp_tx *c_tx = &qp->tx_ctx;
716 	int data_len;
717 
718 	c_tx->ctrl_len =
719 		iwarp_pktinfo[__rdmap_get_opcode(&c_tx->pkt.ctrl)].hdr_len;
720 	c_tx->ctrl_sent = 0;
721 
722 	/*
723 	 * Update target buffer offset if any
724 	 */
725 	if (!(c_tx->pkt.ctrl.ddp_rdmap_ctrl & DDP_FLAG_TAGGED))
726 		/* Untagged message */
727 		c_tx->pkt.c_untagged.ddp_mo = cpu_to_be32(wqe->processed);
728 	else /* Tagged message */
729 		c_tx->pkt.c_tagged.ddp_to =
730 			cpu_to_be64(wqe->sqe.raddr + wqe->processed);
731 
732 	data_len = wqe->bytes - wqe->processed;
733 	if (data_len + c_tx->ctrl_len + MPA_CRC_SIZE > c_tx->tcp_seglen) {
734 		/* Trim DDP payload to fit into current TCP segment */
735 		data_len = c_tx->tcp_seglen - (c_tx->ctrl_len + MPA_CRC_SIZE);
736 		c_tx->pkt.ctrl.ddp_rdmap_ctrl &= ~DDP_FLAG_LAST;
737 		c_tx->pad = 0;
738 	} else {
739 		c_tx->pkt.ctrl.ddp_rdmap_ctrl |= DDP_FLAG_LAST;
740 		c_tx->pad = -data_len & 0x3;
741 	}
742 	c_tx->bytes_unsent = data_len;
743 
744 	c_tx->pkt.ctrl.mpa_len =
745 		htons(c_tx->ctrl_len + data_len - MPA_HDR_SIZE);
746 
747 	/*
748 	 * Init MPA CRC computation
749 	 */
750 	if (c_tx->mpa_crc_hd) {
751 		crypto_shash_init(c_tx->mpa_crc_hd);
752 		crypto_shash_update(c_tx->mpa_crc_hd, (u8 *)&c_tx->pkt,
753 				    c_tx->ctrl_len);
754 		c_tx->do_crc = 1;
755 	}
756 }
757 
758 /*
759  * siw_check_sgl_tx()
760  *
761  * Check permissions for a list of SGE's (SGL).
762  * A successful check will have all memory referenced
763  * for transmission resolved and assigned to the WQE.
764  *
765  * @pd:		Protection Domain SGL should belong to
766  * @wqe:	WQE to be checked
767  * @perms:	requested access permissions
768  *
769  */
770 
771 static int siw_check_sgl_tx(struct ib_pd *pd, struct siw_wqe *wqe,
772 			    enum ib_access_flags perms)
773 {
774 	struct siw_sge *sge = &wqe->sqe.sge[0];
775 	int i, len, num_sge = wqe->sqe.num_sge;
776 
777 	if (unlikely(num_sge > SIW_MAX_SGE))
778 		return -EINVAL;
779 
780 	for (i = 0, len = 0; num_sge; num_sge--, i++, sge++) {
781 		/*
782 		 * rdma verbs: do not check stag for a zero length sge
783 		 */
784 		if (sge->length) {
785 			int rv = siw_check_sge(pd, sge, &wqe->mem[i], perms, 0,
786 					       sge->length);
787 
788 			if (unlikely(rv != E_ACCESS_OK))
789 				return rv;
790 		}
791 		len += sge->length;
792 	}
793 	return len;
794 }
795 
796 /*
797  * siw_qp_sq_proc_tx()
798  *
799  * Process one WQE which needs transmission on the wire.
800  */
801 static int siw_qp_sq_proc_tx(struct siw_qp *qp, struct siw_wqe *wqe)
802 {
803 	struct siw_iwarp_tx *c_tx = &qp->tx_ctx;
804 	struct socket *s = qp->attrs.sk;
805 	int rv = 0, burst_len = qp->tx_ctx.burst;
806 	enum rdmap_ecode ecode = RDMAP_ECODE_CATASTROPHIC_STREAM;
807 
808 	if (unlikely(wqe->wr_status == SIW_WR_IDLE))
809 		return 0;
810 
811 	if (!burst_len)
812 		burst_len = SQ_USER_MAXBURST;
813 
814 	if (wqe->wr_status == SIW_WR_QUEUED) {
815 		if (!(wqe->sqe.flags & SIW_WQE_INLINE)) {
816 			if (tx_type(wqe) == SIW_OP_READ_RESPONSE)
817 				wqe->sqe.num_sge = 1;
818 
819 			if (tx_type(wqe) != SIW_OP_READ &&
820 			    tx_type(wqe) != SIW_OP_READ_LOCAL_INV) {
821 				/*
822 				 * Reference memory to be tx'd w/o checking
823 				 * access for LOCAL_READ permission, since
824 				 * not defined in RDMA core.
825 				 */
826 				rv = siw_check_sgl_tx(qp->pd, wqe, 0);
827 				if (rv < 0) {
828 					if (tx_type(wqe) ==
829 					    SIW_OP_READ_RESPONSE)
830 						ecode = siw_rdmap_error(-rv);
831 					rv = -EINVAL;
832 					goto tx_error;
833 				}
834 				wqe->bytes = rv;
835 			} else {
836 				wqe->bytes = 0;
837 			}
838 		} else {
839 			wqe->bytes = wqe->sqe.sge[0].length;
840 			if (!rdma_is_kernel_res(&qp->base_qp.res)) {
841 				if (wqe->bytes > SIW_MAX_INLINE) {
842 					rv = -EINVAL;
843 					goto tx_error;
844 				}
845 				wqe->sqe.sge[0].laddr =
846 					(u64)(uintptr_t)&wqe->sqe.sge[1];
847 			}
848 		}
849 		wqe->wr_status = SIW_WR_INPROGRESS;
850 		wqe->processed = 0;
851 
852 		siw_update_tcpseg(c_tx, s);
853 
854 		rv = siw_qp_prepare_tx(c_tx);
855 		if (rv == PKT_FRAGMENTED) {
856 			c_tx->state = SIW_SEND_HDR;
857 			siw_prepare_fpdu(qp, wqe);
858 		} else if (rv == PKT_COMPLETE) {
859 			c_tx->state = SIW_SEND_SHORT_FPDU;
860 		} else {
861 			goto tx_error;
862 		}
863 	}
864 
865 next_segment:
866 	siw_dbg_qp(qp, "wr type %d, state %d, data %u, sent %u, id %llx\n",
867 		   tx_type(wqe), wqe->wr_status, wqe->bytes, wqe->processed,
868 		   wqe->sqe.id);
869 
870 	if (--burst_len == 0) {
871 		rv = -EINPROGRESS;
872 		goto tx_done;
873 	}
874 	if (c_tx->state == SIW_SEND_SHORT_FPDU) {
875 		enum siw_opcode tx_type = tx_type(wqe);
876 		unsigned int msg_flags;
877 
878 		if (siw_sq_empty(qp) || !siw_tcp_nagle || burst_len == 1)
879 			/*
880 			 * End current TCP segment, if SQ runs empty,
881 			 * or siw_tcp_nagle is not set, or we bail out
882 			 * soon due to no burst credit left.
883 			 */
884 			msg_flags = MSG_DONTWAIT;
885 		else
886 			msg_flags = MSG_DONTWAIT | MSG_MORE;
887 
888 		rv = siw_tx_ctrl(c_tx, s, msg_flags);
889 
890 		if (!rv && tx_type != SIW_OP_READ &&
891 		    tx_type != SIW_OP_READ_LOCAL_INV)
892 			wqe->processed = wqe->bytes;
893 
894 		goto tx_done;
895 
896 	} else {
897 		rv = siw_tx_hdt(c_tx, s);
898 	}
899 	if (!rv) {
900 		/*
901 		 * One segment sent. Processing completed if last
902 		 * segment, Do next segment otherwise.
903 		 */
904 		if (unlikely(c_tx->tx_suspend)) {
905 			/*
906 			 * Verbs, 6.4.: Try stopping sending after a full
907 			 * DDP segment if the connection goes down
908 			 * (== peer halfclose)
909 			 */
910 			rv = -ECONNABORTED;
911 			goto tx_done;
912 		}
913 		if (c_tx->pkt.ctrl.ddp_rdmap_ctrl & DDP_FLAG_LAST) {
914 			siw_dbg_qp(qp, "WQE completed\n");
915 			goto tx_done;
916 		}
917 		c_tx->state = SIW_SEND_HDR;
918 
919 		siw_update_tcpseg(c_tx, s);
920 
921 		siw_prepare_fpdu(qp, wqe);
922 		goto next_segment;
923 	}
924 tx_done:
925 	qp->tx_ctx.burst = burst_len;
926 	return rv;
927 
928 tx_error:
929 	if (ecode != RDMAP_ECODE_CATASTROPHIC_STREAM)
930 		siw_init_terminate(qp, TERM_ERROR_LAYER_RDMAP,
931 				   RDMAP_ETYPE_REMOTE_PROTECTION, ecode, 1);
932 	else
933 		siw_init_terminate(qp, TERM_ERROR_LAYER_RDMAP,
934 				   RDMAP_ETYPE_CATASTROPHIC,
935 				   RDMAP_ECODE_UNSPECIFIED, 1);
936 	return rv;
937 }
938 
939 static int siw_fastreg_mr(struct ib_pd *pd, struct siw_sqe *sqe)
940 {
941 	struct ib_mr *base_mr = (struct ib_mr *)(uintptr_t)sqe->base_mr;
942 	struct siw_device *sdev = to_siw_dev(pd->device);
943 	struct siw_mem *mem;
944 	int rv = 0;
945 
946 	siw_dbg_pd(pd, "STag 0x%08x\n", sqe->rkey);
947 
948 	if (unlikely(!base_mr)) {
949 		pr_warn("siw: fastreg: STag 0x%08x unknown\n", sqe->rkey);
950 		return -EINVAL;
951 	}
952 
953 	if (unlikely(base_mr->rkey >> 8 != sqe->rkey  >> 8)) {
954 		pr_warn("siw: fastreg: STag 0x%08x: bad MR\n", sqe->rkey);
955 		return -EINVAL;
956 	}
957 
958 	mem = siw_mem_id2obj(sdev, sqe->rkey  >> 8);
959 	if (unlikely(!mem)) {
960 		pr_warn("siw: fastreg: STag 0x%08x unknown\n", sqe->rkey);
961 		return -EINVAL;
962 	}
963 
964 	if (unlikely(mem->pd != pd)) {
965 		pr_warn("siw: fastreg: PD mismatch\n");
966 		rv = -EINVAL;
967 		goto out;
968 	}
969 	if (unlikely(mem->stag_valid)) {
970 		pr_warn("siw: fastreg: STag 0x%08x already valid\n", sqe->rkey);
971 		rv = -EINVAL;
972 		goto out;
973 	}
974 	/* Refresh STag since user may have changed key part */
975 	mem->stag = sqe->rkey;
976 	mem->perms = sqe->access;
977 
978 	siw_dbg_mem(mem, "STag 0x%08x now valid\n", sqe->rkey);
979 	mem->va = base_mr->iova;
980 	mem->stag_valid = 1;
981 out:
982 	siw_mem_put(mem);
983 	return rv;
984 }
985 
986 static int siw_qp_sq_proc_local(struct siw_qp *qp, struct siw_wqe *wqe)
987 {
988 	int rv;
989 
990 	switch (tx_type(wqe)) {
991 	case SIW_OP_REG_MR:
992 		rv = siw_fastreg_mr(qp->pd, &wqe->sqe);
993 		break;
994 
995 	case SIW_OP_INVAL_STAG:
996 		rv = siw_invalidate_stag(qp->pd, wqe->sqe.rkey);
997 		break;
998 
999 	default:
1000 		rv = -EINVAL;
1001 	}
1002 	return rv;
1003 }
1004 
1005 /*
1006  * siw_qp_sq_process()
1007  *
1008  * Core TX path routine for RDMAP/DDP/MPA using a TCP kernel socket.
1009  * Sends RDMAP payload for the current SQ WR @wqe of @qp in one or more
1010  * MPA FPDUs, each containing a DDP segment.
1011  *
1012  * SQ processing may occur in user context as a result of posting
1013  * new WQE's or from siw_sq_work_handler() context. Processing in
1014  * user context is limited to non-kernel verbs users.
1015  *
1016  * SQ processing may get paused anytime, possibly in the middle of a WR
1017  * or FPDU, if insufficient send space is available. SQ processing
1018  * gets resumed from siw_sq_work_handler(), if send space becomes
1019  * available again.
1020  *
1021  * Must be called with the QP state read-locked.
1022  *
1023  * Note:
1024  * An outbound RREQ can be satisfied by the corresponding RRESP
1025  * _before_ it gets assigned to the ORQ. This happens regularly
1026  * in RDMA READ via loopback case. Since both outbound RREQ and
1027  * inbound RRESP can be handled by the same CPU, locking the ORQ
1028  * is dead-lock prone and thus not an option. With that, the
1029  * RREQ gets assigned to the ORQ _before_ being sent - see
1030  * siw_activate_tx() - and pulled back in case of send failure.
1031  */
1032 int siw_qp_sq_process(struct siw_qp *qp)
1033 {
1034 	struct siw_wqe *wqe = tx_wqe(qp);
1035 	enum siw_opcode tx_type;
1036 	unsigned long flags;
1037 	int rv = 0;
1038 
1039 	siw_dbg_qp(qp, "enter for type %d\n", tx_type(wqe));
1040 
1041 next_wqe:
1042 	/*
1043 	 * Stop QP processing if SQ state changed
1044 	 */
1045 	if (unlikely(qp->tx_ctx.tx_suspend)) {
1046 		siw_dbg_qp(qp, "tx suspended\n");
1047 		goto done;
1048 	}
1049 	tx_type = tx_type(wqe);
1050 
1051 	if (tx_type <= SIW_OP_READ_RESPONSE)
1052 		rv = siw_qp_sq_proc_tx(qp, wqe);
1053 	else
1054 		rv = siw_qp_sq_proc_local(qp, wqe);
1055 
1056 	if (!rv) {
1057 		/*
1058 		 * WQE processing done
1059 		 */
1060 		switch (tx_type) {
1061 		case SIW_OP_SEND:
1062 		case SIW_OP_SEND_REMOTE_INV:
1063 		case SIW_OP_WRITE:
1064 			siw_wqe_put_mem(wqe, tx_type);
1065 			fallthrough;
1066 
1067 		case SIW_OP_INVAL_STAG:
1068 		case SIW_OP_REG_MR:
1069 			if (tx_flags(wqe) & SIW_WQE_SIGNALLED)
1070 				siw_sqe_complete(qp, &wqe->sqe, wqe->bytes,
1071 						 SIW_WC_SUCCESS);
1072 			break;
1073 
1074 		case SIW_OP_READ:
1075 		case SIW_OP_READ_LOCAL_INV:
1076 			/*
1077 			 * already enqueued to ORQ queue
1078 			 */
1079 			break;
1080 
1081 		case SIW_OP_READ_RESPONSE:
1082 			siw_wqe_put_mem(wqe, tx_type);
1083 			break;
1084 
1085 		default:
1086 			WARN(1, "undefined WQE type %d\n", tx_type);
1087 			rv = -EINVAL;
1088 			goto done;
1089 		}
1090 
1091 		spin_lock_irqsave(&qp->sq_lock, flags);
1092 		wqe->wr_status = SIW_WR_IDLE;
1093 		rv = siw_activate_tx(qp);
1094 		spin_unlock_irqrestore(&qp->sq_lock, flags);
1095 
1096 		if (rv <= 0)
1097 			goto done;
1098 
1099 		goto next_wqe;
1100 
1101 	} else if (rv == -EAGAIN) {
1102 		siw_dbg_qp(qp, "sq paused: hd/tr %d of %d, data %d\n",
1103 			   qp->tx_ctx.ctrl_sent, qp->tx_ctx.ctrl_len,
1104 			   qp->tx_ctx.bytes_unsent);
1105 		rv = 0;
1106 		goto done;
1107 	} else if (rv == -EINPROGRESS) {
1108 		rv = siw_sq_start(qp);
1109 		goto done;
1110 	} else {
1111 		/*
1112 		 * WQE processing failed.
1113 		 * Verbs 8.3.2:
1114 		 * o It turns any WQE into a signalled WQE.
1115 		 * o Local catastrophic error must be surfaced
1116 		 * o QP must be moved into Terminate state: done by code
1117 		 *   doing socket state change processing
1118 		 *
1119 		 * o TODO: Termination message must be sent.
1120 		 * o TODO: Implement more precise work completion errors,
1121 		 *         see enum ib_wc_status in ib_verbs.h
1122 		 */
1123 		siw_dbg_qp(qp, "wqe type %d processing failed: %d\n",
1124 			   tx_type(wqe), rv);
1125 
1126 		spin_lock_irqsave(&qp->sq_lock, flags);
1127 		/*
1128 		 * RREQ may have already been completed by inbound RRESP!
1129 		 */
1130 		if ((tx_type == SIW_OP_READ ||
1131 		     tx_type == SIW_OP_READ_LOCAL_INV) && qp->attrs.orq_size) {
1132 			/* Cleanup pending entry in ORQ */
1133 			qp->orq_put--;
1134 			qp->orq[qp->orq_put % qp->attrs.orq_size].flags = 0;
1135 		}
1136 		spin_unlock_irqrestore(&qp->sq_lock, flags);
1137 		/*
1138 		 * immediately suspends further TX processing
1139 		 */
1140 		if (!qp->tx_ctx.tx_suspend)
1141 			siw_qp_cm_drop(qp, 0);
1142 
1143 		switch (tx_type) {
1144 		case SIW_OP_SEND:
1145 		case SIW_OP_SEND_REMOTE_INV:
1146 		case SIW_OP_SEND_WITH_IMM:
1147 		case SIW_OP_WRITE:
1148 		case SIW_OP_READ:
1149 		case SIW_OP_READ_LOCAL_INV:
1150 			siw_wqe_put_mem(wqe, tx_type);
1151 			fallthrough;
1152 
1153 		case SIW_OP_INVAL_STAG:
1154 		case SIW_OP_REG_MR:
1155 			siw_sqe_complete(qp, &wqe->sqe, wqe->bytes,
1156 					 SIW_WC_LOC_QP_OP_ERR);
1157 
1158 			siw_qp_event(qp, IB_EVENT_QP_FATAL);
1159 
1160 			break;
1161 
1162 		case SIW_OP_READ_RESPONSE:
1163 			siw_dbg_qp(qp, "proc. read.response failed: %d\n", rv);
1164 
1165 			siw_qp_event(qp, IB_EVENT_QP_REQ_ERR);
1166 
1167 			siw_wqe_put_mem(wqe, SIW_OP_READ_RESPONSE);
1168 
1169 			break;
1170 
1171 		default:
1172 			WARN(1, "undefined WQE type %d\n", tx_type);
1173 			rv = -EINVAL;
1174 		}
1175 		wqe->wr_status = SIW_WR_IDLE;
1176 	}
1177 done:
1178 	return rv;
1179 }
1180 
1181 static void siw_sq_resume(struct siw_qp *qp)
1182 {
1183 	if (down_read_trylock(&qp->state_lock)) {
1184 		if (likely(qp->attrs.state == SIW_QP_STATE_RTS &&
1185 			   !qp->tx_ctx.tx_suspend)) {
1186 			int rv = siw_qp_sq_process(qp);
1187 
1188 			up_read(&qp->state_lock);
1189 
1190 			if (unlikely(rv < 0)) {
1191 				siw_dbg_qp(qp, "SQ task failed: err %d\n", rv);
1192 
1193 				if (!qp->tx_ctx.tx_suspend)
1194 					siw_qp_cm_drop(qp, 0);
1195 			}
1196 		} else {
1197 			up_read(&qp->state_lock);
1198 		}
1199 	} else {
1200 		siw_dbg_qp(qp, "Resume SQ while QP locked\n");
1201 	}
1202 	siw_qp_put(qp);
1203 }
1204 
1205 struct tx_task_t {
1206 	struct llist_head active;
1207 	wait_queue_head_t waiting;
1208 };
1209 
1210 static DEFINE_PER_CPU(struct tx_task_t, siw_tx_task_g);
1211 
1212 void siw_stop_tx_thread(int nr_cpu)
1213 {
1214 	kthread_stop(siw_tx_thread[nr_cpu]);
1215 	wake_up(&per_cpu(siw_tx_task_g, nr_cpu).waiting);
1216 }
1217 
1218 int siw_run_sq(void *data)
1219 {
1220 	const int nr_cpu = (unsigned int)(long)data;
1221 	struct llist_node *active;
1222 	struct siw_qp *qp;
1223 	struct tx_task_t *tx_task = &per_cpu(siw_tx_task_g, nr_cpu);
1224 
1225 	init_llist_head(&tx_task->active);
1226 	init_waitqueue_head(&tx_task->waiting);
1227 
1228 	while (1) {
1229 		struct llist_node *fifo_list = NULL;
1230 
1231 		wait_event_interruptible(tx_task->waiting,
1232 					 !llist_empty(&tx_task->active) ||
1233 						 kthread_should_stop());
1234 
1235 		if (kthread_should_stop())
1236 			break;
1237 
1238 		active = llist_del_all(&tx_task->active);
1239 		/*
1240 		 * llist_del_all returns a list with newest entry first.
1241 		 * Re-order list for fairness among QP's.
1242 		 */
1243 		while (active) {
1244 			struct llist_node *tmp = active;
1245 
1246 			active = llist_next(active);
1247 			tmp->next = fifo_list;
1248 			fifo_list = tmp;
1249 		}
1250 		while (fifo_list) {
1251 			qp = container_of(fifo_list, struct siw_qp, tx_list);
1252 			fifo_list = llist_next(fifo_list);
1253 			qp->tx_list.next = NULL;
1254 
1255 			siw_sq_resume(qp);
1256 		}
1257 	}
1258 	active = llist_del_all(&tx_task->active);
1259 	if (active) {
1260 		llist_for_each_entry(qp, active, tx_list) {
1261 			qp->tx_list.next = NULL;
1262 			siw_sq_resume(qp);
1263 		}
1264 	}
1265 	return 0;
1266 }
1267 
1268 int siw_sq_start(struct siw_qp *qp)
1269 {
1270 	if (tx_wqe(qp)->wr_status == SIW_WR_IDLE)
1271 		return 0;
1272 
1273 	if (unlikely(!cpu_online(qp->tx_cpu))) {
1274 		siw_put_tx_cpu(qp->tx_cpu);
1275 		qp->tx_cpu = siw_get_tx_cpu(qp->sdev);
1276 		if (qp->tx_cpu < 0) {
1277 			pr_warn("siw: no tx cpu available\n");
1278 
1279 			return -EIO;
1280 		}
1281 	}
1282 	siw_qp_get(qp);
1283 
1284 	llist_add(&qp->tx_list, &per_cpu(siw_tx_task_g, qp->tx_cpu).active);
1285 
1286 	wake_up(&per_cpu(siw_tx_task_g, qp->tx_cpu).waiting);
1287 
1288 	return 0;
1289 }
1290