1 // SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause 2 /* 3 * Copyright (c) 2016-2018 Oracle. All rights reserved. 4 * Copyright (c) 2014 Open Grid Computing, Inc. All rights reserved. 5 * Copyright (c) 2005-2006 Network Appliance, Inc. All rights reserved. 6 * 7 * This software is available to you under a choice of one of two 8 * licenses. You may choose to be licensed under the terms of the GNU 9 * General Public License (GPL) Version 2, available from the file 10 * COPYING in the main directory of this source tree, or the BSD-type 11 * license below: 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 17 * Redistributions of source code must retain the above copyright 18 * notice, this list of conditions and the following disclaimer. 19 * 20 * Redistributions in binary form must reproduce the above 21 * copyright notice, this list of conditions and the following 22 * disclaimer in the documentation and/or other materials provided 23 * with the distribution. 24 * 25 * Neither the name of the Network Appliance, Inc. nor the names of 26 * its contributors may be used to endorse or promote products 27 * derived from this software without specific prior written 28 * permission. 29 * 30 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 31 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 32 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 33 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 34 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 35 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 36 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 37 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 38 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 39 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 40 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 41 * 42 * Author: Tom Tucker <tom@opengridcomputing.com> 43 */ 44 45 /* Operation 46 * 47 * The main entry point is svc_rdma_recvfrom. This is called from 48 * svc_recv when the transport indicates there is incoming data to 49 * be read. "Data Ready" is signaled when an RDMA Receive completes, 50 * or when a set of RDMA Reads complete. 51 * 52 * An svc_rqst is passed in. This structure contains an array of 53 * free pages (rq_pages) that will contain the incoming RPC message. 54 * 55 * Short messages are moved directly into svc_rqst::rq_arg, and 56 * the RPC Call is ready to be processed by the Upper Layer. 57 * svc_rdma_recvfrom returns the length of the RPC Call message, 58 * completing the reception of the RPC Call. 59 * 60 * However, when an incoming message has Read chunks, 61 * svc_rdma_recvfrom must post RDMA Reads to pull the RPC Call's 62 * data payload from the client. svc_rdma_recvfrom sets up the 63 * RDMA Reads using pages in svc_rqst::rq_pages, which are 64 * transferred to an svc_rdma_recv_ctxt for the duration of the 65 * I/O. svc_rdma_recvfrom then returns zero, since the RPC message 66 * is still not yet ready. 67 * 68 * When the Read chunk payloads have become available on the 69 * server, "Data Ready" is raised again, and svc_recv calls 70 * svc_rdma_recvfrom again. This second call may use a different 71 * svc_rqst than the first one, thus any information that needs 72 * to be preserved across these two calls is kept in an 73 * svc_rdma_recv_ctxt. 74 * 75 * The second call to svc_rdma_recvfrom performs final assembly 76 * of the RPC Call message, using the RDMA Read sink pages kept in 77 * the svc_rdma_recv_ctxt. The xdr_buf is copied from the 78 * svc_rdma_recv_ctxt to the second svc_rqst. The second call returns 79 * the length of the completed RPC Call message. 80 * 81 * Page Management 82 * 83 * Pages under I/O must be transferred from the first svc_rqst to an 84 * svc_rdma_recv_ctxt before the first svc_rdma_recvfrom call returns. 85 * 86 * The first svc_rqst supplies pages for RDMA Reads. These are moved 87 * from rqstp::rq_pages into ctxt::pages. The consumed elements of 88 * the rq_pages array are set to NULL and refilled with the first 89 * svc_rdma_recvfrom call returns. 90 * 91 * During the second svc_rdma_recvfrom call, RDMA Read sink pages 92 * are transferred from the svc_rdma_recv_ctxt to the second svc_rqst 93 * (see rdma_read_complete() below). 94 */ 95 96 #include <linux/spinlock.h> 97 #include <asm/unaligned.h> 98 #include <rdma/ib_verbs.h> 99 #include <rdma/rdma_cm.h> 100 101 #include <linux/sunrpc/xdr.h> 102 #include <linux/sunrpc/debug.h> 103 #include <linux/sunrpc/rpc_rdma.h> 104 #include <linux/sunrpc/svc_rdma.h> 105 106 #include "xprt_rdma.h" 107 #include <trace/events/rpcrdma.h> 108 109 #define RPCDBG_FACILITY RPCDBG_SVCXPRT 110 111 static void svc_rdma_wc_receive(struct ib_cq *cq, struct ib_wc *wc); 112 113 static inline struct svc_rdma_recv_ctxt * 114 svc_rdma_next_recv_ctxt(struct list_head *list) 115 { 116 return list_first_entry_or_null(list, struct svc_rdma_recv_ctxt, 117 rc_list); 118 } 119 120 static struct svc_rdma_recv_ctxt * 121 svc_rdma_recv_ctxt_alloc(struct svcxprt_rdma *rdma) 122 { 123 struct svc_rdma_recv_ctxt *ctxt; 124 dma_addr_t addr; 125 void *buffer; 126 127 ctxt = kmalloc(sizeof(*ctxt), GFP_KERNEL); 128 if (!ctxt) 129 goto fail0; 130 buffer = kmalloc(rdma->sc_max_req_size, GFP_KERNEL); 131 if (!buffer) 132 goto fail1; 133 addr = ib_dma_map_single(rdma->sc_pd->device, buffer, 134 rdma->sc_max_req_size, DMA_FROM_DEVICE); 135 if (ib_dma_mapping_error(rdma->sc_pd->device, addr)) 136 goto fail2; 137 138 ctxt->rc_recv_wr.next = NULL; 139 ctxt->rc_recv_wr.wr_cqe = &ctxt->rc_cqe; 140 ctxt->rc_recv_wr.sg_list = &ctxt->rc_recv_sge; 141 ctxt->rc_recv_wr.num_sge = 1; 142 ctxt->rc_cqe.done = svc_rdma_wc_receive; 143 ctxt->rc_recv_sge.addr = addr; 144 ctxt->rc_recv_sge.length = rdma->sc_max_req_size; 145 ctxt->rc_recv_sge.lkey = rdma->sc_pd->local_dma_lkey; 146 ctxt->rc_recv_buf = buffer; 147 ctxt->rc_temp = false; 148 return ctxt; 149 150 fail2: 151 kfree(buffer); 152 fail1: 153 kfree(ctxt); 154 fail0: 155 return NULL; 156 } 157 158 static void svc_rdma_recv_ctxt_destroy(struct svcxprt_rdma *rdma, 159 struct svc_rdma_recv_ctxt *ctxt) 160 { 161 ib_dma_unmap_single(rdma->sc_pd->device, ctxt->rc_recv_sge.addr, 162 ctxt->rc_recv_sge.length, DMA_FROM_DEVICE); 163 kfree(ctxt->rc_recv_buf); 164 kfree(ctxt); 165 } 166 167 /** 168 * svc_rdma_recv_ctxts_destroy - Release all recv_ctxt's for an xprt 169 * @rdma: svcxprt_rdma being torn down 170 * 171 */ 172 void svc_rdma_recv_ctxts_destroy(struct svcxprt_rdma *rdma) 173 { 174 struct svc_rdma_recv_ctxt *ctxt; 175 176 while ((ctxt = svc_rdma_next_recv_ctxt(&rdma->sc_recv_ctxts))) { 177 list_del(&ctxt->rc_list); 178 svc_rdma_recv_ctxt_destroy(rdma, ctxt); 179 } 180 } 181 182 static struct svc_rdma_recv_ctxt * 183 svc_rdma_recv_ctxt_get(struct svcxprt_rdma *rdma) 184 { 185 struct svc_rdma_recv_ctxt *ctxt; 186 187 spin_lock(&rdma->sc_recv_lock); 188 ctxt = svc_rdma_next_recv_ctxt(&rdma->sc_recv_ctxts); 189 if (!ctxt) 190 goto out_empty; 191 list_del(&ctxt->rc_list); 192 spin_unlock(&rdma->sc_recv_lock); 193 194 out: 195 ctxt->rc_page_count = 0; 196 return ctxt; 197 198 out_empty: 199 spin_unlock(&rdma->sc_recv_lock); 200 201 ctxt = svc_rdma_recv_ctxt_alloc(rdma); 202 if (!ctxt) 203 return NULL; 204 goto out; 205 } 206 207 /** 208 * svc_rdma_recv_ctxt_put - Return recv_ctxt to free list 209 * @rdma: controlling svcxprt_rdma 210 * @ctxt: object to return to the free list 211 * 212 */ 213 void svc_rdma_recv_ctxt_put(struct svcxprt_rdma *rdma, 214 struct svc_rdma_recv_ctxt *ctxt) 215 { 216 unsigned int i; 217 218 for (i = 0; i < ctxt->rc_page_count; i++) 219 put_page(ctxt->rc_pages[i]); 220 221 if (!ctxt->rc_temp) { 222 spin_lock(&rdma->sc_recv_lock); 223 list_add(&ctxt->rc_list, &rdma->sc_recv_ctxts); 224 spin_unlock(&rdma->sc_recv_lock); 225 } else 226 svc_rdma_recv_ctxt_destroy(rdma, ctxt); 227 } 228 229 static int __svc_rdma_post_recv(struct svcxprt_rdma *rdma, 230 struct svc_rdma_recv_ctxt *ctxt) 231 { 232 int ret; 233 234 svc_xprt_get(&rdma->sc_xprt); 235 ret = ib_post_recv(rdma->sc_qp, &ctxt->rc_recv_wr, NULL); 236 trace_svcrdma_post_recv(&ctxt->rc_recv_wr, ret); 237 if (ret) 238 goto err_post; 239 return 0; 240 241 err_post: 242 svc_rdma_recv_ctxt_put(rdma, ctxt); 243 svc_xprt_put(&rdma->sc_xprt); 244 return ret; 245 } 246 247 static int svc_rdma_post_recv(struct svcxprt_rdma *rdma) 248 { 249 struct svc_rdma_recv_ctxt *ctxt; 250 251 ctxt = svc_rdma_recv_ctxt_get(rdma); 252 if (!ctxt) 253 return -ENOMEM; 254 return __svc_rdma_post_recv(rdma, ctxt); 255 } 256 257 /** 258 * svc_rdma_post_recvs - Post initial set of Recv WRs 259 * @rdma: fresh svcxprt_rdma 260 * 261 * Returns true if successful, otherwise false. 262 */ 263 bool svc_rdma_post_recvs(struct svcxprt_rdma *rdma) 264 { 265 struct svc_rdma_recv_ctxt *ctxt; 266 unsigned int i; 267 int ret; 268 269 for (i = 0; i < rdma->sc_max_requests; i++) { 270 ctxt = svc_rdma_recv_ctxt_get(rdma); 271 if (!ctxt) 272 return false; 273 ctxt->rc_temp = true; 274 ret = __svc_rdma_post_recv(rdma, ctxt); 275 if (ret) { 276 pr_err("svcrdma: failure posting recv buffers: %d\n", 277 ret); 278 return false; 279 } 280 } 281 return true; 282 } 283 284 /** 285 * svc_rdma_wc_receive - Invoked by RDMA provider for each polled Receive WC 286 * @cq: Completion Queue context 287 * @wc: Work Completion object 288 * 289 * NB: The svc_xprt/svcxprt_rdma is pinned whenever it's possible that 290 * the Receive completion handler could be running. 291 */ 292 static void svc_rdma_wc_receive(struct ib_cq *cq, struct ib_wc *wc) 293 { 294 struct svcxprt_rdma *rdma = cq->cq_context; 295 struct ib_cqe *cqe = wc->wr_cqe; 296 struct svc_rdma_recv_ctxt *ctxt; 297 298 trace_svcrdma_wc_receive(wc); 299 300 /* WARNING: Only wc->wr_cqe and wc->status are reliable */ 301 ctxt = container_of(cqe, struct svc_rdma_recv_ctxt, rc_cqe); 302 303 if (wc->status != IB_WC_SUCCESS) 304 goto flushed; 305 306 if (svc_rdma_post_recv(rdma)) 307 goto post_err; 308 309 /* All wc fields are now known to be valid */ 310 ctxt->rc_byte_len = wc->byte_len; 311 ib_dma_sync_single_for_cpu(rdma->sc_pd->device, 312 ctxt->rc_recv_sge.addr, 313 wc->byte_len, DMA_FROM_DEVICE); 314 315 spin_lock(&rdma->sc_rq_dto_lock); 316 list_add_tail(&ctxt->rc_list, &rdma->sc_rq_dto_q); 317 spin_unlock(&rdma->sc_rq_dto_lock); 318 set_bit(XPT_DATA, &rdma->sc_xprt.xpt_flags); 319 if (!test_bit(RDMAXPRT_CONN_PENDING, &rdma->sc_flags)) 320 svc_xprt_enqueue(&rdma->sc_xprt); 321 goto out; 322 323 flushed: 324 if (wc->status != IB_WC_WR_FLUSH_ERR) 325 pr_err("svcrdma: Recv: %s (%u/0x%x)\n", 326 ib_wc_status_msg(wc->status), 327 wc->status, wc->vendor_err); 328 post_err: 329 svc_rdma_recv_ctxt_put(rdma, ctxt); 330 set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags); 331 svc_xprt_enqueue(&rdma->sc_xprt); 332 out: 333 svc_xprt_put(&rdma->sc_xprt); 334 } 335 336 /** 337 * svc_rdma_flush_recv_queues - Drain pending Receive work 338 * @rdma: svcxprt_rdma being shut down 339 * 340 */ 341 void svc_rdma_flush_recv_queues(struct svcxprt_rdma *rdma) 342 { 343 struct svc_rdma_recv_ctxt *ctxt; 344 345 while ((ctxt = svc_rdma_next_recv_ctxt(&rdma->sc_read_complete_q))) { 346 list_del(&ctxt->rc_list); 347 svc_rdma_recv_ctxt_put(rdma, ctxt); 348 } 349 while ((ctxt = svc_rdma_next_recv_ctxt(&rdma->sc_rq_dto_q))) { 350 list_del(&ctxt->rc_list); 351 svc_rdma_recv_ctxt_put(rdma, ctxt); 352 } 353 } 354 355 static void svc_rdma_build_arg_xdr(struct svc_rqst *rqstp, 356 struct svc_rdma_recv_ctxt *ctxt) 357 { 358 struct xdr_buf *arg = &rqstp->rq_arg; 359 360 arg->head[0].iov_base = ctxt->rc_recv_buf; 361 arg->head[0].iov_len = ctxt->rc_byte_len; 362 arg->tail[0].iov_base = NULL; 363 arg->tail[0].iov_len = 0; 364 arg->page_len = 0; 365 arg->page_base = 0; 366 arg->buflen = ctxt->rc_byte_len; 367 arg->len = ctxt->rc_byte_len; 368 369 rqstp->rq_respages = &rqstp->rq_pages[0]; 370 rqstp->rq_next_page = rqstp->rq_respages + 1; 371 } 372 373 /* This accommodates the largest possible Write chunk, 374 * in one segment. 375 */ 376 #define MAX_BYTES_WRITE_SEG ((u32)(RPCSVC_MAXPAGES << PAGE_SHIFT)) 377 378 /* This accommodates the largest possible Position-Zero 379 * Read chunk or Reply chunk, in one segment. 380 */ 381 #define MAX_BYTES_SPECIAL_SEG ((u32)((RPCSVC_MAXPAGES + 2) << PAGE_SHIFT)) 382 383 /* Sanity check the Read list. 384 * 385 * Implementation limits: 386 * - This implementation supports only one Read chunk. 387 * 388 * Sanity checks: 389 * - Read list does not overflow buffer. 390 * - Segment size limited by largest NFS data payload. 391 * 392 * The segment count is limited to how many segments can 393 * fit in the transport header without overflowing the 394 * buffer. That's about 40 Read segments for a 1KB inline 395 * threshold. 396 * 397 * Returns pointer to the following Write list. 398 */ 399 static __be32 *xdr_check_read_list(__be32 *p, const __be32 *end) 400 { 401 u32 position; 402 bool first; 403 404 first = true; 405 while (*p++ != xdr_zero) { 406 if (first) { 407 position = be32_to_cpup(p++); 408 first = false; 409 } else if (be32_to_cpup(p++) != position) { 410 return NULL; 411 } 412 p++; /* handle */ 413 if (be32_to_cpup(p++) > MAX_BYTES_SPECIAL_SEG) 414 return NULL; 415 p += 2; /* offset */ 416 417 if (p > end) 418 return NULL; 419 } 420 return p; 421 } 422 423 /* The segment count is limited to how many segments can 424 * fit in the transport header without overflowing the 425 * buffer. That's about 60 Write segments for a 1KB inline 426 * threshold. 427 */ 428 static __be32 *xdr_check_write_chunk(__be32 *p, const __be32 *end, 429 u32 maxlen) 430 { 431 u32 i, segcount; 432 433 segcount = be32_to_cpup(p++); 434 for (i = 0; i < segcount; i++) { 435 p++; /* handle */ 436 if (be32_to_cpup(p++) > maxlen) 437 return NULL; 438 p += 2; /* offset */ 439 440 if (p > end) 441 return NULL; 442 } 443 444 return p; 445 } 446 447 /* Sanity check the Write list. 448 * 449 * Implementation limits: 450 * - This implementation supports only one Write chunk. 451 * 452 * Sanity checks: 453 * - Write list does not overflow buffer. 454 * - Segment size limited by largest NFS data payload. 455 * 456 * Returns pointer to the following Reply chunk. 457 */ 458 static __be32 *xdr_check_write_list(__be32 *p, const __be32 *end) 459 { 460 u32 chcount; 461 462 chcount = 0; 463 while (*p++ != xdr_zero) { 464 p = xdr_check_write_chunk(p, end, MAX_BYTES_WRITE_SEG); 465 if (!p) 466 return NULL; 467 if (chcount++ > 1) 468 return NULL; 469 } 470 return p; 471 } 472 473 /* Sanity check the Reply chunk. 474 * 475 * Sanity checks: 476 * - Reply chunk does not overflow buffer. 477 * - Segment size limited by largest NFS data payload. 478 * 479 * Returns pointer to the following RPC header. 480 */ 481 static __be32 *xdr_check_reply_chunk(__be32 *p, const __be32 *end) 482 { 483 if (*p++ != xdr_zero) { 484 p = xdr_check_write_chunk(p, end, MAX_BYTES_SPECIAL_SEG); 485 if (!p) 486 return NULL; 487 } 488 return p; 489 } 490 491 /* On entry, xdr->head[0].iov_base points to first byte in the 492 * RPC-over-RDMA header. 493 * 494 * On successful exit, head[0] points to first byte past the 495 * RPC-over-RDMA header. For RDMA_MSG, this is the RPC message. 496 * The length of the RPC-over-RDMA header is returned. 497 * 498 * Assumptions: 499 * - The transport header is entirely contained in the head iovec. 500 */ 501 static int svc_rdma_xdr_decode_req(struct xdr_buf *rq_arg) 502 { 503 __be32 *p, *end, *rdma_argp; 504 unsigned int hdr_len; 505 506 /* Verify that there's enough bytes for header + something */ 507 if (rq_arg->len <= RPCRDMA_HDRLEN_ERR) 508 goto out_short; 509 510 rdma_argp = rq_arg->head[0].iov_base; 511 if (*(rdma_argp + 1) != rpcrdma_version) 512 goto out_version; 513 514 switch (*(rdma_argp + 3)) { 515 case rdma_msg: 516 break; 517 case rdma_nomsg: 518 break; 519 520 case rdma_done: 521 goto out_drop; 522 523 case rdma_error: 524 goto out_drop; 525 526 default: 527 goto out_proc; 528 } 529 530 end = (__be32 *)((unsigned long)rdma_argp + rq_arg->len); 531 p = xdr_check_read_list(rdma_argp + 4, end); 532 if (!p) 533 goto out_inval; 534 p = xdr_check_write_list(p, end); 535 if (!p) 536 goto out_inval; 537 p = xdr_check_reply_chunk(p, end); 538 if (!p) 539 goto out_inval; 540 if (p > end) 541 goto out_inval; 542 543 rq_arg->head[0].iov_base = p; 544 hdr_len = (unsigned long)p - (unsigned long)rdma_argp; 545 rq_arg->head[0].iov_len -= hdr_len; 546 rq_arg->len -= hdr_len; 547 trace_svcrdma_decode_rqst(rdma_argp, hdr_len); 548 return hdr_len; 549 550 out_short: 551 trace_svcrdma_decode_short(rq_arg->len); 552 return -EINVAL; 553 554 out_version: 555 trace_svcrdma_decode_badvers(rdma_argp); 556 return -EPROTONOSUPPORT; 557 558 out_drop: 559 trace_svcrdma_decode_drop(rdma_argp); 560 return 0; 561 562 out_proc: 563 trace_svcrdma_decode_badproc(rdma_argp); 564 return -EINVAL; 565 566 out_inval: 567 trace_svcrdma_decode_parse(rdma_argp); 568 return -EINVAL; 569 } 570 571 static void rdma_read_complete(struct svc_rqst *rqstp, 572 struct svc_rdma_recv_ctxt *head) 573 { 574 int page_no; 575 576 /* Move Read chunk pages to rqstp so that they will be released 577 * when svc_process is done with them. 578 */ 579 for (page_no = 0; page_no < head->rc_page_count; page_no++) { 580 put_page(rqstp->rq_pages[page_no]); 581 rqstp->rq_pages[page_no] = head->rc_pages[page_no]; 582 } 583 head->rc_page_count = 0; 584 585 /* Point rq_arg.pages past header */ 586 rqstp->rq_arg.pages = &rqstp->rq_pages[head->rc_hdr_count]; 587 rqstp->rq_arg.page_len = head->rc_arg.page_len; 588 589 /* rq_respages starts after the last arg page */ 590 rqstp->rq_respages = &rqstp->rq_pages[page_no]; 591 rqstp->rq_next_page = rqstp->rq_respages + 1; 592 593 /* Rebuild rq_arg head and tail. */ 594 rqstp->rq_arg.head[0] = head->rc_arg.head[0]; 595 rqstp->rq_arg.tail[0] = head->rc_arg.tail[0]; 596 rqstp->rq_arg.len = head->rc_arg.len; 597 rqstp->rq_arg.buflen = head->rc_arg.buflen; 598 } 599 600 static void svc_rdma_send_error(struct svcxprt_rdma *xprt, 601 __be32 *rdma_argp, int status) 602 { 603 struct svc_rdma_send_ctxt *ctxt; 604 unsigned int length; 605 __be32 *p; 606 int ret; 607 608 ctxt = svc_rdma_send_ctxt_get(xprt); 609 if (!ctxt) 610 return; 611 612 p = ctxt->sc_xprt_buf; 613 *p++ = *rdma_argp; 614 *p++ = *(rdma_argp + 1); 615 *p++ = xprt->sc_fc_credits; 616 *p++ = rdma_error; 617 switch (status) { 618 case -EPROTONOSUPPORT: 619 *p++ = err_vers; 620 *p++ = rpcrdma_version; 621 *p++ = rpcrdma_version; 622 trace_svcrdma_err_vers(*rdma_argp); 623 break; 624 default: 625 *p++ = err_chunk; 626 trace_svcrdma_err_chunk(*rdma_argp); 627 } 628 length = (unsigned long)p - (unsigned long)ctxt->sc_xprt_buf; 629 svc_rdma_sync_reply_hdr(xprt, ctxt, length); 630 631 ctxt->sc_send_wr.opcode = IB_WR_SEND; 632 ret = svc_rdma_send(xprt, &ctxt->sc_send_wr); 633 if (ret) 634 svc_rdma_send_ctxt_put(xprt, ctxt); 635 } 636 637 /* By convention, backchannel calls arrive via rdma_msg type 638 * messages, and never populate the chunk lists. This makes 639 * the RPC/RDMA header small and fixed in size, so it is 640 * straightforward to check the RPC header's direction field. 641 */ 642 static bool svc_rdma_is_backchannel_reply(struct svc_xprt *xprt, 643 __be32 *rdma_resp) 644 { 645 __be32 *p; 646 647 if (!xprt->xpt_bc_xprt) 648 return false; 649 650 p = rdma_resp + 3; 651 if (*p++ != rdma_msg) 652 return false; 653 654 if (*p++ != xdr_zero) 655 return false; 656 if (*p++ != xdr_zero) 657 return false; 658 if (*p++ != xdr_zero) 659 return false; 660 661 /* XID sanity */ 662 if (*p++ != *rdma_resp) 663 return false; 664 /* call direction */ 665 if (*p == cpu_to_be32(RPC_CALL)) 666 return false; 667 668 return true; 669 } 670 671 /** 672 * svc_rdma_recvfrom - Receive an RPC call 673 * @rqstp: request structure into which to receive an RPC Call 674 * 675 * Returns: 676 * The positive number of bytes in the RPC Call message, 677 * %0 if there were no Calls ready to return, 678 * %-EINVAL if the Read chunk data is too large, 679 * %-ENOMEM if rdma_rw context pool was exhausted, 680 * %-ENOTCONN if posting failed (connection is lost), 681 * %-EIO if rdma_rw initialization failed (DMA mapping, etc). 682 * 683 * Called in a loop when XPT_DATA is set. XPT_DATA is cleared only 684 * when there are no remaining ctxt's to process. 685 * 686 * The next ctxt is removed from the "receive" lists. 687 * 688 * - If the ctxt completes a Read, then finish assembling the Call 689 * message and return the number of bytes in the message. 690 * 691 * - If the ctxt completes a Receive, then construct the Call 692 * message from the contents of the Receive buffer. 693 * 694 * - If there are no Read chunks in this message, then finish 695 * assembling the Call message and return the number of bytes 696 * in the message. 697 * 698 * - If there are Read chunks in this message, post Read WRs to 699 * pull that payload and return 0. 700 */ 701 int svc_rdma_recvfrom(struct svc_rqst *rqstp) 702 { 703 struct svc_xprt *xprt = rqstp->rq_xprt; 704 struct svcxprt_rdma *rdma_xprt = 705 container_of(xprt, struct svcxprt_rdma, sc_xprt); 706 struct svc_rdma_recv_ctxt *ctxt; 707 __be32 *p; 708 int ret; 709 710 spin_lock(&rdma_xprt->sc_rq_dto_lock); 711 ctxt = svc_rdma_next_recv_ctxt(&rdma_xprt->sc_read_complete_q); 712 if (ctxt) { 713 list_del(&ctxt->rc_list); 714 spin_unlock(&rdma_xprt->sc_rq_dto_lock); 715 rdma_read_complete(rqstp, ctxt); 716 goto complete; 717 } 718 ctxt = svc_rdma_next_recv_ctxt(&rdma_xprt->sc_rq_dto_q); 719 if (!ctxt) { 720 /* No new incoming requests, terminate the loop */ 721 clear_bit(XPT_DATA, &xprt->xpt_flags); 722 spin_unlock(&rdma_xprt->sc_rq_dto_lock); 723 return 0; 724 } 725 list_del(&ctxt->rc_list); 726 spin_unlock(&rdma_xprt->sc_rq_dto_lock); 727 728 atomic_inc(&rdma_stat_recv); 729 730 svc_rdma_build_arg_xdr(rqstp, ctxt); 731 732 p = (__be32 *)rqstp->rq_arg.head[0].iov_base; 733 ret = svc_rdma_xdr_decode_req(&rqstp->rq_arg); 734 if (ret < 0) 735 goto out_err; 736 if (ret == 0) 737 goto out_drop; 738 rqstp->rq_xprt_hlen = ret; 739 740 if (svc_rdma_is_backchannel_reply(xprt, p)) { 741 ret = svc_rdma_handle_bc_reply(xprt->xpt_bc_xprt, p, 742 &rqstp->rq_arg); 743 svc_rdma_recv_ctxt_put(rdma_xprt, ctxt); 744 return ret; 745 } 746 747 p += rpcrdma_fixed_maxsz; 748 if (*p != xdr_zero) 749 goto out_readchunk; 750 751 complete: 752 rqstp->rq_xprt_ctxt = ctxt; 753 rqstp->rq_prot = IPPROTO_MAX; 754 svc_xprt_copy_addrs(rqstp, xprt); 755 return rqstp->rq_arg.len; 756 757 out_readchunk: 758 ret = svc_rdma_recv_read_chunk(rdma_xprt, rqstp, ctxt, p); 759 if (ret < 0) 760 goto out_postfail; 761 return 0; 762 763 out_err: 764 svc_rdma_send_error(rdma_xprt, p, ret); 765 svc_rdma_recv_ctxt_put(rdma_xprt, ctxt); 766 return 0; 767 768 out_postfail: 769 if (ret == -EINVAL) 770 svc_rdma_send_error(rdma_xprt, p, ret); 771 svc_rdma_recv_ctxt_put(rdma_xprt, ctxt); 772 return ret; 773 774 out_drop: 775 svc_rdma_recv_ctxt_put(rdma_xprt, ctxt); 776 return 0; 777 } 778