xref: /openbmc/linux/drivers/infiniband/hw/hfi1/ruc.c (revision 2cf1c348)
1 // SPDX-License-Identifier: GPL-2.0 or BSD-3-Clause
2 /*
3  * Copyright(c) 2015 - 2018 Intel Corporation.
4  */
5 
6 #include <linux/spinlock.h>
7 
8 #include "hfi.h"
9 #include "mad.h"
10 #include "qp.h"
11 #include "verbs_txreq.h"
12 #include "trace.h"
13 
14 static int gid_ok(union ib_gid *gid, __be64 gid_prefix, __be64 id)
15 {
16 	return (gid->global.interface_id == id &&
17 		(gid->global.subnet_prefix == gid_prefix ||
18 		 gid->global.subnet_prefix == IB_DEFAULT_GID_PREFIX));
19 }
20 
21 /*
22  *
23  * This should be called with the QP r_lock held.
24  *
25  * The s_lock will be acquired around the hfi1_migrate_qp() call.
26  */
27 int hfi1_ruc_check_hdr(struct hfi1_ibport *ibp, struct hfi1_packet *packet)
28 {
29 	__be64 guid;
30 	unsigned long flags;
31 	struct rvt_qp *qp = packet->qp;
32 	u8 sc5 = ibp->sl_to_sc[rdma_ah_get_sl(&qp->remote_ah_attr)];
33 	u32 dlid = packet->dlid;
34 	u32 slid = packet->slid;
35 	u32 sl = packet->sl;
36 	bool migrated = packet->migrated;
37 	u16 pkey = packet->pkey;
38 
39 	if (qp->s_mig_state == IB_MIG_ARMED && migrated) {
40 		if (!packet->grh) {
41 			if ((rdma_ah_get_ah_flags(&qp->alt_ah_attr) &
42 			     IB_AH_GRH) &&
43 			    (packet->etype != RHF_RCV_TYPE_BYPASS))
44 				return 1;
45 		} else {
46 			const struct ib_global_route *grh;
47 
48 			if (!(rdma_ah_get_ah_flags(&qp->alt_ah_attr) &
49 			      IB_AH_GRH))
50 				return 1;
51 			grh = rdma_ah_read_grh(&qp->alt_ah_attr);
52 			guid = get_sguid(ibp, grh->sgid_index);
53 			if (!gid_ok(&packet->grh->dgid, ibp->rvp.gid_prefix,
54 				    guid))
55 				return 1;
56 			if (!gid_ok(
57 				&packet->grh->sgid,
58 				grh->dgid.global.subnet_prefix,
59 				grh->dgid.global.interface_id))
60 				return 1;
61 		}
62 		if (unlikely(rcv_pkey_check(ppd_from_ibp(ibp), pkey,
63 					    sc5, slid))) {
64 			hfi1_bad_pkey(ibp, pkey, sl, 0, qp->ibqp.qp_num,
65 				      slid, dlid);
66 			return 1;
67 		}
68 		/* Validate the SLID. See Ch. 9.6.1.5 and 17.2.8 */
69 		if (slid != rdma_ah_get_dlid(&qp->alt_ah_attr) ||
70 		    ppd_from_ibp(ibp)->port !=
71 			rdma_ah_get_port_num(&qp->alt_ah_attr))
72 			return 1;
73 		spin_lock_irqsave(&qp->s_lock, flags);
74 		hfi1_migrate_qp(qp);
75 		spin_unlock_irqrestore(&qp->s_lock, flags);
76 	} else {
77 		if (!packet->grh) {
78 			if ((rdma_ah_get_ah_flags(&qp->remote_ah_attr) &
79 			     IB_AH_GRH) &&
80 			    (packet->etype != RHF_RCV_TYPE_BYPASS))
81 				return 1;
82 		} else {
83 			const struct ib_global_route *grh;
84 
85 			if (!(rdma_ah_get_ah_flags(&qp->remote_ah_attr) &
86 						   IB_AH_GRH))
87 				return 1;
88 			grh = rdma_ah_read_grh(&qp->remote_ah_attr);
89 			guid = get_sguid(ibp, grh->sgid_index);
90 			if (!gid_ok(&packet->grh->dgid, ibp->rvp.gid_prefix,
91 				    guid))
92 				return 1;
93 			if (!gid_ok(
94 			     &packet->grh->sgid,
95 			     grh->dgid.global.subnet_prefix,
96 			     grh->dgid.global.interface_id))
97 				return 1;
98 		}
99 		if (unlikely(rcv_pkey_check(ppd_from_ibp(ibp), pkey,
100 					    sc5, slid))) {
101 			hfi1_bad_pkey(ibp, pkey, sl, 0, qp->ibqp.qp_num,
102 				      slid, dlid);
103 			return 1;
104 		}
105 		/* Validate the SLID. See Ch. 9.6.1.5 */
106 		if ((slid != rdma_ah_get_dlid(&qp->remote_ah_attr)) ||
107 		    ppd_from_ibp(ibp)->port != qp->port_num)
108 			return 1;
109 		if (qp->s_mig_state == IB_MIG_REARM && !migrated)
110 			qp->s_mig_state = IB_MIG_ARMED;
111 	}
112 
113 	return 0;
114 }
115 
116 /**
117  * hfi1_make_grh - construct a GRH header
118  * @ibp: a pointer to the IB port
119  * @hdr: a pointer to the GRH header being constructed
120  * @grh: the global route address to send to
121  * @hwords: size of header after grh being sent in dwords
122  * @nwords: the number of 32 bit words of data being sent
123  *
124  * Return the size of the header in 32 bit words.
125  */
126 u32 hfi1_make_grh(struct hfi1_ibport *ibp, struct ib_grh *hdr,
127 		  const struct ib_global_route *grh, u32 hwords, u32 nwords)
128 {
129 	hdr->version_tclass_flow =
130 		cpu_to_be32((IB_GRH_VERSION << IB_GRH_VERSION_SHIFT) |
131 			    (grh->traffic_class << IB_GRH_TCLASS_SHIFT) |
132 			    (grh->flow_label << IB_GRH_FLOW_SHIFT));
133 	hdr->paylen = cpu_to_be16((hwords + nwords) << 2);
134 	/* next_hdr is defined by C8-7 in ch. 8.4.1 */
135 	hdr->next_hdr = IB_GRH_NEXT_HDR;
136 	hdr->hop_limit = grh->hop_limit;
137 	/* The SGID is 32-bit aligned. */
138 	hdr->sgid.global.subnet_prefix = ibp->rvp.gid_prefix;
139 	hdr->sgid.global.interface_id =
140 		grh->sgid_index < HFI1_GUIDS_PER_PORT ?
141 		get_sguid(ibp, grh->sgid_index) :
142 		get_sguid(ibp, HFI1_PORT_GUID_INDEX);
143 	hdr->dgid = grh->dgid;
144 
145 	/* GRH header size in 32-bit words. */
146 	return sizeof(struct ib_grh) / sizeof(u32);
147 }
148 
149 #define BTH2_OFFSET (offsetof(struct hfi1_sdma_header, \
150 			      hdr.ibh.u.oth.bth[2]) / 4)
151 
152 /**
153  * build_ahg - create ahg in s_ahg
154  * @qp: a pointer to QP
155  * @npsn: the next PSN for the request/response
156  *
157  * This routine handles the AHG by allocating an ahg entry and causing the
158  * copy of the first middle.
159  *
160  * Subsequent middles use the copied entry, editing the
161  * PSN with 1 or 2 edits.
162  */
163 static inline void build_ahg(struct rvt_qp *qp, u32 npsn)
164 {
165 	struct hfi1_qp_priv *priv = qp->priv;
166 
167 	if (unlikely(qp->s_flags & HFI1_S_AHG_CLEAR))
168 		clear_ahg(qp);
169 	if (!(qp->s_flags & HFI1_S_AHG_VALID)) {
170 		/* first middle that needs copy  */
171 		if (qp->s_ahgidx < 0)
172 			qp->s_ahgidx = sdma_ahg_alloc(priv->s_sde);
173 		if (qp->s_ahgidx >= 0) {
174 			qp->s_ahgpsn = npsn;
175 			priv->s_ahg->tx_flags |= SDMA_TXREQ_F_AHG_COPY;
176 			/* save to protect a change in another thread */
177 			priv->s_ahg->ahgidx = qp->s_ahgidx;
178 			qp->s_flags |= HFI1_S_AHG_VALID;
179 		}
180 	} else {
181 		/* subsequent middle after valid */
182 		if (qp->s_ahgidx >= 0) {
183 			priv->s_ahg->tx_flags |= SDMA_TXREQ_F_USE_AHG;
184 			priv->s_ahg->ahgidx = qp->s_ahgidx;
185 			priv->s_ahg->ahgcount++;
186 			priv->s_ahg->ahgdesc[0] =
187 				sdma_build_ahg_descriptor(
188 					(__force u16)cpu_to_be16((u16)npsn),
189 					BTH2_OFFSET,
190 					16,
191 					16);
192 			if ((npsn & 0xffff0000) !=
193 					(qp->s_ahgpsn & 0xffff0000)) {
194 				priv->s_ahg->ahgcount++;
195 				priv->s_ahg->ahgdesc[1] =
196 					sdma_build_ahg_descriptor(
197 						(__force u16)cpu_to_be16(
198 							(u16)(npsn >> 16)),
199 						BTH2_OFFSET,
200 						0,
201 						16);
202 			}
203 		}
204 	}
205 }
206 
207 static inline void hfi1_make_ruc_bth(struct rvt_qp *qp,
208 				     struct ib_other_headers *ohdr,
209 				     u32 bth0, u32 bth1, u32 bth2)
210 {
211 	ohdr->bth[0] = cpu_to_be32(bth0);
212 	ohdr->bth[1] = cpu_to_be32(bth1);
213 	ohdr->bth[2] = cpu_to_be32(bth2);
214 }
215 
216 /**
217  * hfi1_make_ruc_header_16B - build a 16B header
218  * @qp: the queue pair
219  * @ohdr: a pointer to the destination header memory
220  * @bth0: bth0 passed in from the RC/UC builder
221  * @bth1: bth1 passed in from the RC/UC builder
222  * @bth2: bth2 passed in from the RC/UC builder
223  * @middle: non zero implies indicates ahg "could" be used
224  * @ps: the current packet state
225  *
226  * This routine may disarm ahg under these situations:
227  * - packet needs a GRH
228  * - BECN needed
229  * - migration state not IB_MIG_MIGRATED
230  */
231 static inline void hfi1_make_ruc_header_16B(struct rvt_qp *qp,
232 					    struct ib_other_headers *ohdr,
233 					    u32 bth0, u32 bth1, u32 bth2,
234 					    int middle,
235 					    struct hfi1_pkt_state *ps)
236 {
237 	struct hfi1_qp_priv *priv = qp->priv;
238 	struct hfi1_ibport *ibp = ps->ibp;
239 	struct hfi1_pportdata *ppd = ppd_from_ibp(ibp);
240 	u32 slid;
241 	u16 pkey = hfi1_get_pkey(ibp, qp->s_pkey_index);
242 	u8 l4 = OPA_16B_L4_IB_LOCAL;
243 	u8 extra_bytes = hfi1_get_16b_padding(
244 				(ps->s_txreq->hdr_dwords << 2),
245 				ps->s_txreq->s_cur_size);
246 	u32 nwords = SIZE_OF_CRC + ((ps->s_txreq->s_cur_size +
247 				 extra_bytes + SIZE_OF_LT) >> 2);
248 	bool becn = false;
249 
250 	if (unlikely(rdma_ah_get_ah_flags(&qp->remote_ah_attr) & IB_AH_GRH) &&
251 	    hfi1_check_mcast(rdma_ah_get_dlid(&qp->remote_ah_attr))) {
252 		struct ib_grh *grh;
253 		struct ib_global_route *grd =
254 			rdma_ah_retrieve_grh(&qp->remote_ah_attr);
255 		/*
256 		 * Ensure OPA GIDs are transformed to IB gids
257 		 * before creating the GRH.
258 		 */
259 		if (grd->sgid_index == OPA_GID_INDEX)
260 			grd->sgid_index = 0;
261 		grh = &ps->s_txreq->phdr.hdr.opah.u.l.grh;
262 		l4 = OPA_16B_L4_IB_GLOBAL;
263 		ps->s_txreq->hdr_dwords +=
264 			hfi1_make_grh(ibp, grh, grd,
265 				      ps->s_txreq->hdr_dwords - LRH_16B_DWORDS,
266 				      nwords);
267 		middle = 0;
268 	}
269 
270 	if (qp->s_mig_state == IB_MIG_MIGRATED)
271 		bth1 |= OPA_BTH_MIG_REQ;
272 	else
273 		middle = 0;
274 
275 	if (qp->s_flags & RVT_S_ECN) {
276 		qp->s_flags &= ~RVT_S_ECN;
277 		/* we recently received a FECN, so return a BECN */
278 		becn = true;
279 		middle = 0;
280 	}
281 	if (middle)
282 		build_ahg(qp, bth2);
283 	else
284 		qp->s_flags &= ~HFI1_S_AHG_VALID;
285 
286 	bth0 |= pkey;
287 	bth0 |= extra_bytes << 20;
288 	hfi1_make_ruc_bth(qp, ohdr, bth0, bth1, bth2);
289 
290 	if (!ppd->lid)
291 		slid = be32_to_cpu(OPA_LID_PERMISSIVE);
292 	else
293 		slid = ppd->lid |
294 			(rdma_ah_get_path_bits(&qp->remote_ah_attr) &
295 			((1 << ppd->lmc) - 1));
296 
297 	hfi1_make_16b_hdr(&ps->s_txreq->phdr.hdr.opah,
298 			  slid,
299 			  opa_get_lid(rdma_ah_get_dlid(&qp->remote_ah_attr),
300 				      16B),
301 			  (ps->s_txreq->hdr_dwords + nwords) >> 1,
302 			  pkey, becn, 0, l4, priv->s_sc);
303 }
304 
305 /**
306  * hfi1_make_ruc_header_9B - build a 9B header
307  * @qp: the queue pair
308  * @ohdr: a pointer to the destination header memory
309  * @bth0: bth0 passed in from the RC/UC builder
310  * @bth1: bth1 passed in from the RC/UC builder
311  * @bth2: bth2 passed in from the RC/UC builder
312  * @middle: non zero implies indicates ahg "could" be used
313  * @ps: the current packet state
314  *
315  * This routine may disarm ahg under these situations:
316  * - packet needs a GRH
317  * - BECN needed
318  * - migration state not IB_MIG_MIGRATED
319  */
320 static inline void hfi1_make_ruc_header_9B(struct rvt_qp *qp,
321 					   struct ib_other_headers *ohdr,
322 					   u32 bth0, u32 bth1, u32 bth2,
323 					   int middle,
324 					   struct hfi1_pkt_state *ps)
325 {
326 	struct hfi1_qp_priv *priv = qp->priv;
327 	struct hfi1_ibport *ibp = ps->ibp;
328 	u16 pkey = hfi1_get_pkey(ibp, qp->s_pkey_index);
329 	u16 lrh0 = HFI1_LRH_BTH;
330 	u8 extra_bytes = -ps->s_txreq->s_cur_size & 3;
331 	u32 nwords = SIZE_OF_CRC + ((ps->s_txreq->s_cur_size +
332 					 extra_bytes) >> 2);
333 
334 	if (unlikely(rdma_ah_get_ah_flags(&qp->remote_ah_attr) & IB_AH_GRH)) {
335 		struct ib_grh *grh = &ps->s_txreq->phdr.hdr.ibh.u.l.grh;
336 
337 		lrh0 = HFI1_LRH_GRH;
338 		ps->s_txreq->hdr_dwords +=
339 			hfi1_make_grh(ibp, grh,
340 				      rdma_ah_read_grh(&qp->remote_ah_attr),
341 				      ps->s_txreq->hdr_dwords - LRH_9B_DWORDS,
342 				      nwords);
343 		middle = 0;
344 	}
345 	lrh0 |= (priv->s_sc & 0xf) << 12 |
346 		(rdma_ah_get_sl(&qp->remote_ah_attr) & 0xf) << 4;
347 
348 	if (qp->s_mig_state == IB_MIG_MIGRATED)
349 		bth0 |= IB_BTH_MIG_REQ;
350 	else
351 		middle = 0;
352 
353 	if (qp->s_flags & RVT_S_ECN) {
354 		qp->s_flags &= ~RVT_S_ECN;
355 		/* we recently received a FECN, so return a BECN */
356 		bth1 |= (IB_BECN_MASK << IB_BECN_SHIFT);
357 		middle = 0;
358 	}
359 	if (middle)
360 		build_ahg(qp, bth2);
361 	else
362 		qp->s_flags &= ~HFI1_S_AHG_VALID;
363 
364 	bth0 |= pkey;
365 	bth0 |= extra_bytes << 20;
366 	hfi1_make_ruc_bth(qp, ohdr, bth0, bth1, bth2);
367 	hfi1_make_ib_hdr(&ps->s_txreq->phdr.hdr.ibh,
368 			 lrh0,
369 			 ps->s_txreq->hdr_dwords + nwords,
370 			 opa_get_lid(rdma_ah_get_dlid(&qp->remote_ah_attr), 9B),
371 			 ppd_from_ibp(ibp)->lid |
372 				rdma_ah_get_path_bits(&qp->remote_ah_attr));
373 }
374 
375 typedef void (*hfi1_make_ruc_hdr)(struct rvt_qp *qp,
376 				  struct ib_other_headers *ohdr,
377 				  u32 bth0, u32 bth1, u32 bth2, int middle,
378 				  struct hfi1_pkt_state *ps);
379 
380 /* We support only two types - 9B and 16B for now */
381 static const hfi1_make_ruc_hdr hfi1_ruc_header_tbl[2] = {
382 	[HFI1_PKT_TYPE_9B] = &hfi1_make_ruc_header_9B,
383 	[HFI1_PKT_TYPE_16B] = &hfi1_make_ruc_header_16B
384 };
385 
386 void hfi1_make_ruc_header(struct rvt_qp *qp, struct ib_other_headers *ohdr,
387 			  u32 bth0, u32 bth1, u32 bth2, int middle,
388 			  struct hfi1_pkt_state *ps)
389 {
390 	struct hfi1_qp_priv *priv = qp->priv;
391 
392 	/*
393 	 * reset s_ahg/AHG fields
394 	 *
395 	 * This insures that the ahgentry/ahgcount
396 	 * are at a non-AHG default to protect
397 	 * build_verbs_tx_desc() from using
398 	 * an include ahgidx.
399 	 *
400 	 * build_ahg() will modify as appropriate
401 	 * to use the AHG feature.
402 	 */
403 	priv->s_ahg->tx_flags = 0;
404 	priv->s_ahg->ahgcount = 0;
405 	priv->s_ahg->ahgidx = 0;
406 
407 	/* Make the appropriate header */
408 	hfi1_ruc_header_tbl[priv->hdr_type](qp, ohdr, bth0, bth1, bth2, middle,
409 					    ps);
410 }
411 
412 /* when sending, force a reschedule every one of these periods */
413 #define SEND_RESCHED_TIMEOUT (5 * HZ)  /* 5s in jiffies */
414 
415 /**
416  * hfi1_schedule_send_yield - test for a yield required for QP
417  * send engine
418  * @qp: a pointer to QP
419  * @ps: a pointer to a structure with commonly lookup values for
420  *      the send engine progress
421  * @tid: true if it is the tid leg
422  *
423  * This routine checks if the time slice for the QP has expired
424  * for RC QPs, if so an additional work entry is queued. At this
425  * point, other QPs have an opportunity to be scheduled. It
426  * returns true if a yield is required, otherwise, false
427  * is returned.
428  */
429 bool hfi1_schedule_send_yield(struct rvt_qp *qp, struct hfi1_pkt_state *ps,
430 			      bool tid)
431 {
432 	ps->pkts_sent = true;
433 
434 	if (unlikely(time_after(jiffies, ps->timeout))) {
435 		if (!ps->in_thread ||
436 		    workqueue_congested(ps->cpu, ps->ppd->hfi1_wq)) {
437 			spin_lock_irqsave(&qp->s_lock, ps->flags);
438 			if (!tid) {
439 				qp->s_flags &= ~RVT_S_BUSY;
440 				hfi1_schedule_send(qp);
441 			} else {
442 				struct hfi1_qp_priv *priv = qp->priv;
443 
444 				if (priv->s_flags &
445 				    HFI1_S_TID_BUSY_SET) {
446 					qp->s_flags &= ~RVT_S_BUSY;
447 					priv->s_flags &=
448 						~(HFI1_S_TID_BUSY_SET |
449 						  RVT_S_BUSY);
450 				} else {
451 					priv->s_flags &= ~RVT_S_BUSY;
452 				}
453 				hfi1_schedule_tid_send(qp);
454 			}
455 
456 			spin_unlock_irqrestore(&qp->s_lock, ps->flags);
457 			this_cpu_inc(*ps->ppd->dd->send_schedule);
458 			trace_hfi1_rc_expired_time_slice(qp, true);
459 			return true;
460 		}
461 
462 		cond_resched();
463 		this_cpu_inc(*ps->ppd->dd->send_schedule);
464 		ps->timeout = jiffies + ps->timeout_int;
465 	}
466 
467 	trace_hfi1_rc_expired_time_slice(qp, false);
468 	return false;
469 }
470 
471 void hfi1_do_send_from_rvt(struct rvt_qp *qp)
472 {
473 	hfi1_do_send(qp, false);
474 }
475 
476 void _hfi1_do_send(struct work_struct *work)
477 {
478 	struct iowait_work *w = container_of(work, struct iowait_work, iowork);
479 	struct rvt_qp *qp = iowait_to_qp(w->iow);
480 
481 	hfi1_do_send(qp, true);
482 }
483 
484 /**
485  * hfi1_do_send - perform a send on a QP
486  * @qp: a pointer to the QP
487  * @in_thread: true if in a workqueue thread
488  *
489  * Process entries in the send work queue until credit or queue is
490  * exhausted.  Only allow one CPU to send a packet per QP.
491  * Otherwise, two threads could send packets out of order.
492  */
493 void hfi1_do_send(struct rvt_qp *qp, bool in_thread)
494 {
495 	struct hfi1_pkt_state ps;
496 	struct hfi1_qp_priv *priv = qp->priv;
497 	int (*make_req)(struct rvt_qp *qp, struct hfi1_pkt_state *ps);
498 
499 	ps.dev = to_idev(qp->ibqp.device);
500 	ps.ibp = to_iport(qp->ibqp.device, qp->port_num);
501 	ps.ppd = ppd_from_ibp(ps.ibp);
502 	ps.in_thread = in_thread;
503 	ps.wait = iowait_get_ib_work(&priv->s_iowait);
504 
505 	trace_hfi1_rc_do_send(qp, in_thread);
506 
507 	switch (qp->ibqp.qp_type) {
508 	case IB_QPT_RC:
509 		if (!loopback && ((rdma_ah_get_dlid(&qp->remote_ah_attr) &
510 				   ~((1 << ps.ppd->lmc) - 1)) ==
511 				  ps.ppd->lid)) {
512 			rvt_ruc_loopback(qp);
513 			return;
514 		}
515 		make_req = hfi1_make_rc_req;
516 		ps.timeout_int = qp->timeout_jiffies;
517 		break;
518 	case IB_QPT_UC:
519 		if (!loopback && ((rdma_ah_get_dlid(&qp->remote_ah_attr) &
520 				   ~((1 << ps.ppd->lmc) - 1)) ==
521 				  ps.ppd->lid)) {
522 			rvt_ruc_loopback(qp);
523 			return;
524 		}
525 		make_req = hfi1_make_uc_req;
526 		ps.timeout_int = SEND_RESCHED_TIMEOUT;
527 		break;
528 	default:
529 		make_req = hfi1_make_ud_req;
530 		ps.timeout_int = SEND_RESCHED_TIMEOUT;
531 	}
532 
533 	spin_lock_irqsave(&qp->s_lock, ps.flags);
534 
535 	/* Return if we are already busy processing a work request. */
536 	if (!hfi1_send_ok(qp)) {
537 		if (qp->s_flags & HFI1_S_ANY_WAIT_IO)
538 			iowait_set_flag(&priv->s_iowait, IOWAIT_PENDING_IB);
539 		spin_unlock_irqrestore(&qp->s_lock, ps.flags);
540 		return;
541 	}
542 
543 	qp->s_flags |= RVT_S_BUSY;
544 
545 	ps.timeout_int = ps.timeout_int / 8;
546 	ps.timeout = jiffies + ps.timeout_int;
547 	ps.cpu = priv->s_sde ? priv->s_sde->cpu :
548 			cpumask_first(cpumask_of_node(ps.ppd->dd->node));
549 	ps.pkts_sent = false;
550 
551 	/* insure a pre-built packet is handled  */
552 	ps.s_txreq = get_waiting_verbs_txreq(ps.wait);
553 	do {
554 		/* Check for a constructed packet to be sent. */
555 		if (ps.s_txreq) {
556 			if (priv->s_flags & HFI1_S_TID_BUSY_SET)
557 				qp->s_flags |= RVT_S_BUSY;
558 			spin_unlock_irqrestore(&qp->s_lock, ps.flags);
559 			/*
560 			 * If the packet cannot be sent now, return and
561 			 * the send engine will be woken up later.
562 			 */
563 			if (hfi1_verbs_send(qp, &ps))
564 				return;
565 
566 			/* allow other tasks to run */
567 			if (hfi1_schedule_send_yield(qp, &ps, false))
568 				return;
569 
570 			spin_lock_irqsave(&qp->s_lock, ps.flags);
571 		}
572 	} while (make_req(qp, &ps));
573 	iowait_starve_clear(ps.pkts_sent, &priv->s_iowait);
574 	spin_unlock_irqrestore(&qp->s_lock, ps.flags);
575 }
576