1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (c) 2015, 2017 Oracle. All rights reserved.
4 * Copyright (c) 2003-2007 Network Appliance, Inc. All rights reserved.
5 */
6
7 /* Lightweight memory registration using Fast Registration Work
8 * Requests (FRWR).
9 *
10 * FRWR features ordered asynchronous registration and invalidation
11 * of arbitrarily-sized memory regions. This is the fastest and safest
12 * but most complex memory registration mode.
13 */
14
15 /* Normal operation
16 *
17 * A Memory Region is prepared for RDMA Read or Write using a FAST_REG
18 * Work Request (frwr_map). When the RDMA operation is finished, this
19 * Memory Region is invalidated using a LOCAL_INV Work Request
20 * (frwr_unmap_async and frwr_unmap_sync).
21 *
22 * Typically FAST_REG Work Requests are not signaled, and neither are
23 * RDMA Send Work Requests (with the exception of signaling occasionally
24 * to prevent provider work queue overflows). This greatly reduces HCA
25 * interrupt workload.
26 */
27
28 /* Transport recovery
29 *
30 * frwr_map and frwr_unmap_* cannot run at the same time the transport
31 * connect worker is running. The connect worker holds the transport
32 * send lock, just as ->send_request does. This prevents frwr_map and
33 * the connect worker from running concurrently. When a connection is
34 * closed, the Receive completion queue is drained before the allowing
35 * the connect worker to get control. This prevents frwr_unmap and the
36 * connect worker from running concurrently.
37 *
38 * When the underlying transport disconnects, MRs that are in flight
39 * are flushed and are likely unusable. Thus all MRs are destroyed.
40 * New MRs are created on demand.
41 */
42
43 #include <linux/sunrpc/svc_rdma.h>
44
45 #include "xprt_rdma.h"
46 #include <trace/events/rpcrdma.h>
47
48 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
49 # define RPCDBG_FACILITY RPCDBG_TRANS
50 #endif
51
52 /**
53 * frwr_release_mr - Destroy one MR
54 * @mr: MR allocated by frwr_mr_init
55 *
56 */
frwr_release_mr(struct rpcrdma_mr * mr)57 void frwr_release_mr(struct rpcrdma_mr *mr)
58 {
59 int rc;
60
61 rc = ib_dereg_mr(mr->frwr.fr_mr);
62 if (rc)
63 trace_xprtrdma_frwr_dereg(mr, rc);
64 kfree(mr->mr_sg);
65 kfree(mr);
66 }
67
frwr_mr_recycle(struct rpcrdma_mr * mr)68 static void frwr_mr_recycle(struct rpcrdma_mr *mr)
69 {
70 struct rpcrdma_xprt *r_xprt = mr->mr_xprt;
71
72 trace_xprtrdma_mr_recycle(mr);
73
74 if (mr->mr_dir != DMA_NONE) {
75 trace_xprtrdma_mr_unmap(mr);
76 ib_dma_unmap_sg(r_xprt->rx_ep->re_id->device,
77 mr->mr_sg, mr->mr_nents, mr->mr_dir);
78 mr->mr_dir = DMA_NONE;
79 }
80
81 spin_lock(&r_xprt->rx_buf.rb_lock);
82 list_del(&mr->mr_all);
83 r_xprt->rx_stats.mrs_recycled++;
84 spin_unlock(&r_xprt->rx_buf.rb_lock);
85
86 frwr_release_mr(mr);
87 }
88
89 /* frwr_reset - Place MRs back on the free list
90 * @req: request to reset
91 *
92 * Used after a failed marshal. For FRWR, this means the MRs
93 * don't have to be fully released and recreated.
94 *
95 * NB: This is safe only as long as none of @req's MRs are
96 * involved with an ongoing asynchronous FAST_REG or LOCAL_INV
97 * Work Request.
98 */
frwr_reset(struct rpcrdma_req * req)99 void frwr_reset(struct rpcrdma_req *req)
100 {
101 struct rpcrdma_mr *mr;
102
103 while ((mr = rpcrdma_mr_pop(&req->rl_registered)))
104 rpcrdma_mr_put(mr);
105 }
106
107 /**
108 * frwr_mr_init - Initialize one MR
109 * @r_xprt: controlling transport instance
110 * @mr: generic MR to prepare for FRWR
111 *
112 * Returns zero if successful. Otherwise a negative errno
113 * is returned.
114 */
frwr_mr_init(struct rpcrdma_xprt * r_xprt,struct rpcrdma_mr * mr)115 int frwr_mr_init(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr *mr)
116 {
117 struct rpcrdma_ep *ep = r_xprt->rx_ep;
118 unsigned int depth = ep->re_max_fr_depth;
119 struct scatterlist *sg;
120 struct ib_mr *frmr;
121 int rc;
122
123 frmr = ib_alloc_mr(ep->re_pd, ep->re_mrtype, depth);
124 if (IS_ERR(frmr))
125 goto out_mr_err;
126
127 sg = kmalloc_array(depth, sizeof(*sg), GFP_NOFS);
128 if (!sg)
129 goto out_list_err;
130
131 mr->mr_xprt = r_xprt;
132 mr->frwr.fr_mr = frmr;
133 mr->mr_dir = DMA_NONE;
134 INIT_LIST_HEAD(&mr->mr_list);
135 init_completion(&mr->frwr.fr_linv_done);
136
137 sg_init_table(sg, depth);
138 mr->mr_sg = sg;
139 return 0;
140
141 out_mr_err:
142 rc = PTR_ERR(frmr);
143 trace_xprtrdma_frwr_alloc(mr, rc);
144 return rc;
145
146 out_list_err:
147 ib_dereg_mr(frmr);
148 return -ENOMEM;
149 }
150
151 /**
152 * frwr_query_device - Prepare a transport for use with FRWR
153 * @ep: endpoint to fill in
154 * @device: RDMA device to query
155 *
156 * On success, sets:
157 * ep->re_attr
158 * ep->re_max_requests
159 * ep->re_max_rdma_segs
160 * ep->re_max_fr_depth
161 * ep->re_mrtype
162 *
163 * Return values:
164 * On success, returns zero.
165 * %-EINVAL - the device does not support FRWR memory registration
166 * %-ENOMEM - the device is not sufficiently capable for NFS/RDMA
167 */
frwr_query_device(struct rpcrdma_ep * ep,const struct ib_device * device)168 int frwr_query_device(struct rpcrdma_ep *ep, const struct ib_device *device)
169 {
170 const struct ib_device_attr *attrs = &device->attrs;
171 int max_qp_wr, depth, delta;
172 unsigned int max_sge;
173
174 if (!(attrs->device_cap_flags & IB_DEVICE_MEM_MGT_EXTENSIONS) ||
175 attrs->max_fast_reg_page_list_len == 0) {
176 pr_err("rpcrdma: 'frwr' mode is not supported by device %s\n",
177 device->name);
178 return -EINVAL;
179 }
180
181 max_sge = min_t(unsigned int, attrs->max_send_sge,
182 RPCRDMA_MAX_SEND_SGES);
183 if (max_sge < RPCRDMA_MIN_SEND_SGES) {
184 pr_err("rpcrdma: HCA provides only %u send SGEs\n", max_sge);
185 return -ENOMEM;
186 }
187 ep->re_attr.cap.max_send_sge = max_sge;
188 ep->re_attr.cap.max_recv_sge = 1;
189
190 ep->re_mrtype = IB_MR_TYPE_MEM_REG;
191 if (attrs->device_cap_flags & IB_DEVICE_SG_GAPS_REG)
192 ep->re_mrtype = IB_MR_TYPE_SG_GAPS;
193
194 /* Quirk: Some devices advertise a large max_fast_reg_page_list_len
195 * capability, but perform optimally when the MRs are not larger
196 * than a page.
197 */
198 if (attrs->max_sge_rd > RPCRDMA_MAX_HDR_SEGS)
199 ep->re_max_fr_depth = attrs->max_sge_rd;
200 else
201 ep->re_max_fr_depth = attrs->max_fast_reg_page_list_len;
202 if (ep->re_max_fr_depth > RPCRDMA_MAX_DATA_SEGS)
203 ep->re_max_fr_depth = RPCRDMA_MAX_DATA_SEGS;
204
205 /* Add room for frwr register and invalidate WRs.
206 * 1. FRWR reg WR for head
207 * 2. FRWR invalidate WR for head
208 * 3. N FRWR reg WRs for pagelist
209 * 4. N FRWR invalidate WRs for pagelist
210 * 5. FRWR reg WR for tail
211 * 6. FRWR invalidate WR for tail
212 * 7. The RDMA_SEND WR
213 */
214 depth = 7;
215
216 /* Calculate N if the device max FRWR depth is smaller than
217 * RPCRDMA_MAX_DATA_SEGS.
218 */
219 if (ep->re_max_fr_depth < RPCRDMA_MAX_DATA_SEGS) {
220 delta = RPCRDMA_MAX_DATA_SEGS - ep->re_max_fr_depth;
221 do {
222 depth += 2; /* FRWR reg + invalidate */
223 delta -= ep->re_max_fr_depth;
224 } while (delta > 0);
225 }
226
227 max_qp_wr = attrs->max_qp_wr;
228 max_qp_wr -= RPCRDMA_BACKWARD_WRS;
229 max_qp_wr -= 1;
230 if (max_qp_wr < RPCRDMA_MIN_SLOT_TABLE)
231 return -ENOMEM;
232 if (ep->re_max_requests > max_qp_wr)
233 ep->re_max_requests = max_qp_wr;
234 ep->re_attr.cap.max_send_wr = ep->re_max_requests * depth;
235 if (ep->re_attr.cap.max_send_wr > max_qp_wr) {
236 ep->re_max_requests = max_qp_wr / depth;
237 if (!ep->re_max_requests)
238 return -ENOMEM;
239 ep->re_attr.cap.max_send_wr = ep->re_max_requests * depth;
240 }
241 ep->re_attr.cap.max_send_wr += RPCRDMA_BACKWARD_WRS;
242 ep->re_attr.cap.max_send_wr += 1; /* for ib_drain_sq */
243 ep->re_attr.cap.max_recv_wr = ep->re_max_requests;
244 ep->re_attr.cap.max_recv_wr += RPCRDMA_BACKWARD_WRS;
245 ep->re_attr.cap.max_recv_wr += 1; /* for ib_drain_rq */
246
247 ep->re_max_rdma_segs =
248 DIV_ROUND_UP(RPCRDMA_MAX_DATA_SEGS, ep->re_max_fr_depth);
249 /* Reply chunks require segments for head and tail buffers */
250 ep->re_max_rdma_segs += 2;
251 if (ep->re_max_rdma_segs > RPCRDMA_MAX_HDR_SEGS)
252 ep->re_max_rdma_segs = RPCRDMA_MAX_HDR_SEGS;
253
254 /* Ensure the underlying device is capable of conveying the
255 * largest r/wsize NFS will ask for. This guarantees that
256 * failing over from one RDMA device to another will not
257 * break NFS I/O.
258 */
259 if ((ep->re_max_rdma_segs * ep->re_max_fr_depth) < RPCRDMA_MAX_SEGS)
260 return -ENOMEM;
261
262 return 0;
263 }
264
265 /**
266 * frwr_map - Register a memory region
267 * @r_xprt: controlling transport
268 * @seg: memory region co-ordinates
269 * @nsegs: number of segments remaining
270 * @writing: true when RDMA Write will be used
271 * @xid: XID of RPC using the registered memory
272 * @mr: MR to fill in
273 *
274 * Prepare a REG_MR Work Request to register a memory region
275 * for remote access via RDMA READ or RDMA WRITE.
276 *
277 * Returns the next segment or a negative errno pointer.
278 * On success, @mr is filled in.
279 */
frwr_map(struct rpcrdma_xprt * r_xprt,struct rpcrdma_mr_seg * seg,int nsegs,bool writing,__be32 xid,struct rpcrdma_mr * mr)280 struct rpcrdma_mr_seg *frwr_map(struct rpcrdma_xprt *r_xprt,
281 struct rpcrdma_mr_seg *seg,
282 int nsegs, bool writing, __be32 xid,
283 struct rpcrdma_mr *mr)
284 {
285 struct rpcrdma_ep *ep = r_xprt->rx_ep;
286 struct ib_reg_wr *reg_wr;
287 int i, n, dma_nents;
288 struct ib_mr *ibmr;
289 u8 key;
290
291 if (nsegs > ep->re_max_fr_depth)
292 nsegs = ep->re_max_fr_depth;
293 for (i = 0; i < nsegs;) {
294 if (seg->mr_page)
295 sg_set_page(&mr->mr_sg[i],
296 seg->mr_page,
297 seg->mr_len,
298 offset_in_page(seg->mr_offset));
299 else
300 sg_set_buf(&mr->mr_sg[i], seg->mr_offset,
301 seg->mr_len);
302
303 ++seg;
304 ++i;
305 if (ep->re_mrtype == IB_MR_TYPE_SG_GAPS)
306 continue;
307 if ((i < nsegs && offset_in_page(seg->mr_offset)) ||
308 offset_in_page((seg-1)->mr_offset + (seg-1)->mr_len))
309 break;
310 }
311 mr->mr_dir = rpcrdma_data_dir(writing);
312 mr->mr_nents = i;
313
314 dma_nents = ib_dma_map_sg(ep->re_id->device, mr->mr_sg, mr->mr_nents,
315 mr->mr_dir);
316 if (!dma_nents)
317 goto out_dmamap_err;
318
319 ibmr = mr->frwr.fr_mr;
320 n = ib_map_mr_sg(ibmr, mr->mr_sg, dma_nents, NULL, PAGE_SIZE);
321 if (n != dma_nents)
322 goto out_mapmr_err;
323
324 ibmr->iova &= 0x00000000ffffffff;
325 ibmr->iova |= ((u64)be32_to_cpu(xid)) << 32;
326 key = (u8)(ibmr->rkey & 0x000000FF);
327 ib_update_fast_reg_key(ibmr, ++key);
328
329 reg_wr = &mr->frwr.fr_regwr;
330 reg_wr->mr = ibmr;
331 reg_wr->key = ibmr->rkey;
332 reg_wr->access = writing ?
333 IB_ACCESS_REMOTE_WRITE | IB_ACCESS_LOCAL_WRITE :
334 IB_ACCESS_REMOTE_READ;
335
336 mr->mr_handle = ibmr->rkey;
337 mr->mr_length = ibmr->length;
338 mr->mr_offset = ibmr->iova;
339 trace_xprtrdma_mr_map(mr);
340
341 return seg;
342
343 out_dmamap_err:
344 mr->mr_dir = DMA_NONE;
345 trace_xprtrdma_frwr_sgerr(mr, i);
346 return ERR_PTR(-EIO);
347
348 out_mapmr_err:
349 trace_xprtrdma_frwr_maperr(mr, n);
350 return ERR_PTR(-EIO);
351 }
352
353 /**
354 * frwr_wc_fastreg - Invoked by RDMA provider for a flushed FastReg WC
355 * @cq: completion queue
356 * @wc: WCE for a completed FastReg WR
357 *
358 */
frwr_wc_fastreg(struct ib_cq * cq,struct ib_wc * wc)359 static void frwr_wc_fastreg(struct ib_cq *cq, struct ib_wc *wc)
360 {
361 struct ib_cqe *cqe = wc->wr_cqe;
362 struct rpcrdma_frwr *frwr =
363 container_of(cqe, struct rpcrdma_frwr, fr_cqe);
364
365 /* WARNING: Only wr_cqe and status are reliable at this point */
366 trace_xprtrdma_wc_fastreg(wc, frwr);
367 /* The MR will get recycled when the associated req is retransmitted */
368
369 rpcrdma_flush_disconnect(cq->cq_context, wc);
370 }
371
372 /**
373 * frwr_send - post Send WRs containing the RPC Call message
374 * @r_xprt: controlling transport instance
375 * @req: prepared RPC Call
376 *
377 * For FRWR, chain any FastReg WRs to the Send WR. Only a
378 * single ib_post_send call is needed to register memory
379 * and then post the Send WR.
380 *
381 * Returns the return code from ib_post_send.
382 *
383 * Caller must hold the transport send lock to ensure that the
384 * pointers to the transport's rdma_cm_id and QP are stable.
385 */
frwr_send(struct rpcrdma_xprt * r_xprt,struct rpcrdma_req * req)386 int frwr_send(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
387 {
388 struct ib_send_wr *post_wr;
389 struct rpcrdma_mr *mr;
390
391 post_wr = &req->rl_wr;
392 list_for_each_entry(mr, &req->rl_registered, mr_list) {
393 struct rpcrdma_frwr *frwr;
394
395 frwr = &mr->frwr;
396
397 frwr->fr_cqe.done = frwr_wc_fastreg;
398 frwr->fr_regwr.wr.next = post_wr;
399 frwr->fr_regwr.wr.wr_cqe = &frwr->fr_cqe;
400 frwr->fr_regwr.wr.num_sge = 0;
401 frwr->fr_regwr.wr.opcode = IB_WR_REG_MR;
402 frwr->fr_regwr.wr.send_flags = 0;
403
404 post_wr = &frwr->fr_regwr.wr;
405 }
406
407 return ib_post_send(r_xprt->rx_ep->re_id->qp, post_wr, NULL);
408 }
409
410 /**
411 * frwr_reminv - handle a remotely invalidated mr on the @mrs list
412 * @rep: Received reply
413 * @mrs: list of MRs to check
414 *
415 */
frwr_reminv(struct rpcrdma_rep * rep,struct list_head * mrs)416 void frwr_reminv(struct rpcrdma_rep *rep, struct list_head *mrs)
417 {
418 struct rpcrdma_mr *mr;
419
420 list_for_each_entry(mr, mrs, mr_list)
421 if (mr->mr_handle == rep->rr_inv_rkey) {
422 list_del_init(&mr->mr_list);
423 trace_xprtrdma_mr_reminv(mr);
424 rpcrdma_mr_put(mr);
425 break; /* only one invalidated MR per RPC */
426 }
427 }
428
__frwr_release_mr(struct ib_wc * wc,struct rpcrdma_mr * mr)429 static void __frwr_release_mr(struct ib_wc *wc, struct rpcrdma_mr *mr)
430 {
431 if (wc->status != IB_WC_SUCCESS)
432 frwr_mr_recycle(mr);
433 else
434 rpcrdma_mr_put(mr);
435 }
436
437 /**
438 * frwr_wc_localinv - Invoked by RDMA provider for a LOCAL_INV WC
439 * @cq: completion queue
440 * @wc: WCE for a completed LocalInv WR
441 *
442 */
frwr_wc_localinv(struct ib_cq * cq,struct ib_wc * wc)443 static void frwr_wc_localinv(struct ib_cq *cq, struct ib_wc *wc)
444 {
445 struct ib_cqe *cqe = wc->wr_cqe;
446 struct rpcrdma_frwr *frwr =
447 container_of(cqe, struct rpcrdma_frwr, fr_cqe);
448 struct rpcrdma_mr *mr = container_of(frwr, struct rpcrdma_mr, frwr);
449
450 /* WARNING: Only wr_cqe and status are reliable at this point */
451 trace_xprtrdma_wc_li(wc, frwr);
452 __frwr_release_mr(wc, mr);
453
454 rpcrdma_flush_disconnect(cq->cq_context, wc);
455 }
456
457 /**
458 * frwr_wc_localinv_wake - Invoked by RDMA provider for a LOCAL_INV WC
459 * @cq: completion queue
460 * @wc: WCE for a completed LocalInv WR
461 *
462 * Awaken anyone waiting for an MR to finish being fenced.
463 */
frwr_wc_localinv_wake(struct ib_cq * cq,struct ib_wc * wc)464 static void frwr_wc_localinv_wake(struct ib_cq *cq, struct ib_wc *wc)
465 {
466 struct ib_cqe *cqe = wc->wr_cqe;
467 struct rpcrdma_frwr *frwr =
468 container_of(cqe, struct rpcrdma_frwr, fr_cqe);
469 struct rpcrdma_mr *mr = container_of(frwr, struct rpcrdma_mr, frwr);
470
471 /* WARNING: Only wr_cqe and status are reliable at this point */
472 trace_xprtrdma_wc_li_wake(wc, frwr);
473 __frwr_release_mr(wc, mr);
474 complete(&frwr->fr_linv_done);
475
476 rpcrdma_flush_disconnect(cq->cq_context, wc);
477 }
478
479 /**
480 * frwr_unmap_sync - invalidate memory regions that were registered for @req
481 * @r_xprt: controlling transport instance
482 * @req: rpcrdma_req with a non-empty list of MRs to process
483 *
484 * Sleeps until it is safe for the host CPU to access the previously mapped
485 * memory regions. This guarantees that registered MRs are properly fenced
486 * from the server before the RPC consumer accesses the data in them. It
487 * also ensures proper Send flow control: waking the next RPC waits until
488 * this RPC has relinquished all its Send Queue entries.
489 */
frwr_unmap_sync(struct rpcrdma_xprt * r_xprt,struct rpcrdma_req * req)490 void frwr_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
491 {
492 struct ib_send_wr *first, **prev, *last;
493 const struct ib_send_wr *bad_wr;
494 struct rpcrdma_frwr *frwr;
495 struct rpcrdma_mr *mr;
496 int rc;
497
498 /* ORDER: Invalidate all of the MRs first
499 *
500 * Chain the LOCAL_INV Work Requests and post them with
501 * a single ib_post_send() call.
502 */
503 frwr = NULL;
504 prev = &first;
505 while ((mr = rpcrdma_mr_pop(&req->rl_registered))) {
506
507 trace_xprtrdma_mr_localinv(mr);
508 r_xprt->rx_stats.local_inv_needed++;
509
510 frwr = &mr->frwr;
511 frwr->fr_cqe.done = frwr_wc_localinv;
512 last = &frwr->fr_invwr;
513 last->next = NULL;
514 last->wr_cqe = &frwr->fr_cqe;
515 last->sg_list = NULL;
516 last->num_sge = 0;
517 last->opcode = IB_WR_LOCAL_INV;
518 last->send_flags = IB_SEND_SIGNALED;
519 last->ex.invalidate_rkey = mr->mr_handle;
520
521 *prev = last;
522 prev = &last->next;
523 }
524
525 /* Strong send queue ordering guarantees that when the
526 * last WR in the chain completes, all WRs in the chain
527 * are complete.
528 */
529 frwr->fr_cqe.done = frwr_wc_localinv_wake;
530 reinit_completion(&frwr->fr_linv_done);
531
532 /* Transport disconnect drains the receive CQ before it
533 * replaces the QP. The RPC reply handler won't call us
534 * unless re_id->qp is a valid pointer.
535 */
536 bad_wr = NULL;
537 rc = ib_post_send(r_xprt->rx_ep->re_id->qp, first, &bad_wr);
538
539 /* The final LOCAL_INV WR in the chain is supposed to
540 * do the wake. If it was never posted, the wake will
541 * not happen, so don't wait in that case.
542 */
543 if (bad_wr != first)
544 wait_for_completion(&frwr->fr_linv_done);
545 if (!rc)
546 return;
547
548 /* Recycle MRs in the LOCAL_INV chain that did not get posted.
549 */
550 trace_xprtrdma_post_linv(req, rc);
551 while (bad_wr) {
552 frwr = container_of(bad_wr, struct rpcrdma_frwr,
553 fr_invwr);
554 mr = container_of(frwr, struct rpcrdma_mr, frwr);
555 bad_wr = bad_wr->next;
556
557 list_del_init(&mr->mr_list);
558 frwr_mr_recycle(mr);
559 }
560 }
561
562 /**
563 * frwr_wc_localinv_done - Invoked by RDMA provider for a signaled LOCAL_INV WC
564 * @cq: completion queue
565 * @wc: WCE for a completed LocalInv WR
566 *
567 */
frwr_wc_localinv_done(struct ib_cq * cq,struct ib_wc * wc)568 static void frwr_wc_localinv_done(struct ib_cq *cq, struct ib_wc *wc)
569 {
570 struct ib_cqe *cqe = wc->wr_cqe;
571 struct rpcrdma_frwr *frwr =
572 container_of(cqe, struct rpcrdma_frwr, fr_cqe);
573 struct rpcrdma_mr *mr = container_of(frwr, struct rpcrdma_mr, frwr);
574 struct rpcrdma_rep *rep = mr->mr_req->rl_reply;
575
576 /* WARNING: Only wr_cqe and status are reliable at this point */
577 trace_xprtrdma_wc_li_done(wc, frwr);
578 __frwr_release_mr(wc, mr);
579
580 /* Ensure @rep is generated before __frwr_release_mr */
581 smp_rmb();
582 rpcrdma_complete_rqst(rep);
583
584 rpcrdma_flush_disconnect(cq->cq_context, wc);
585 }
586
587 /**
588 * frwr_unmap_async - invalidate memory regions that were registered for @req
589 * @r_xprt: controlling transport instance
590 * @req: rpcrdma_req with a non-empty list of MRs to process
591 *
592 * This guarantees that registered MRs are properly fenced from the
593 * server before the RPC consumer accesses the data in them. It also
594 * ensures proper Send flow control: waking the next RPC waits until
595 * this RPC has relinquished all its Send Queue entries.
596 */
frwr_unmap_async(struct rpcrdma_xprt * r_xprt,struct rpcrdma_req * req)597 void frwr_unmap_async(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
598 {
599 struct ib_send_wr *first, *last, **prev;
600 const struct ib_send_wr *bad_wr;
601 struct rpcrdma_frwr *frwr;
602 struct rpcrdma_mr *mr;
603 int rc;
604
605 /* Chain the LOCAL_INV Work Requests and post them with
606 * a single ib_post_send() call.
607 */
608 frwr = NULL;
609 prev = &first;
610 while ((mr = rpcrdma_mr_pop(&req->rl_registered))) {
611
612 trace_xprtrdma_mr_localinv(mr);
613 r_xprt->rx_stats.local_inv_needed++;
614
615 frwr = &mr->frwr;
616 frwr->fr_cqe.done = frwr_wc_localinv;
617 last = &frwr->fr_invwr;
618 last->next = NULL;
619 last->wr_cqe = &frwr->fr_cqe;
620 last->sg_list = NULL;
621 last->num_sge = 0;
622 last->opcode = IB_WR_LOCAL_INV;
623 last->send_flags = IB_SEND_SIGNALED;
624 last->ex.invalidate_rkey = mr->mr_handle;
625
626 *prev = last;
627 prev = &last->next;
628 }
629
630 /* Strong send queue ordering guarantees that when the
631 * last WR in the chain completes, all WRs in the chain
632 * are complete. The last completion will wake up the
633 * RPC waiter.
634 */
635 frwr->fr_cqe.done = frwr_wc_localinv_done;
636
637 /* Transport disconnect drains the receive CQ before it
638 * replaces the QP. The RPC reply handler won't call us
639 * unless re_id->qp is a valid pointer.
640 */
641 bad_wr = NULL;
642 rc = ib_post_send(r_xprt->rx_ep->re_id->qp, first, &bad_wr);
643 if (!rc)
644 return;
645
646 /* Recycle MRs in the LOCAL_INV chain that did not get posted.
647 */
648 trace_xprtrdma_post_linv(req, rc);
649 while (bad_wr) {
650 frwr = container_of(bad_wr, struct rpcrdma_frwr, fr_invwr);
651 mr = container_of(frwr, struct rpcrdma_mr, frwr);
652 bad_wr = bad_wr->next;
653
654 frwr_mr_recycle(mr);
655 }
656
657 /* The final LOCAL_INV WR in the chain is supposed to
658 * do the wake. If it was never posted, the wake will
659 * not happen, so wake here in that case.
660 */
661 rpcrdma_complete_rqst(req->rl_reply);
662 }
663
