1 // SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
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.
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42 * Author: Tom Tucker <tom@opengridcomputing.com>
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.
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.
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.
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.
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
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.
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.
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.
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.
95 #include <linux/slab.h>
96 #include <linux/spinlock.h>
97 #include <asm/unaligned.h>
98 #include <rdma/ib_verbs.h>
99 #include <rdma/rdma_cm.h>
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>
106 #include "xprt_rdma.h"
107 #include <trace/events/rpcrdma.h>
109 static void svc_rdma_wc_receive(struct ib_cq *cq, struct ib_wc *wc);
111 static inline struct svc_rdma_recv_ctxt *
112 svc_rdma_next_recv_ctxt(struct list_head *list)
114 return list_first_entry_or_null(list, struct svc_rdma_recv_ctxt,
118 static void svc_rdma_recv_cid_init(struct svcxprt_rdma *rdma,
119 struct rpc_rdma_cid *cid)
121 cid->ci_queue_id = rdma->sc_rq_cq->res.id;
122 cid->ci_completion_id = atomic_inc_return(&rdma->sc_completion_ids);
125 static struct svc_rdma_recv_ctxt *
126 svc_rdma_recv_ctxt_alloc(struct svcxprt_rdma *rdma)
128 struct svc_rdma_recv_ctxt *ctxt;
132 ctxt = kmalloc(sizeof(*ctxt), GFP_KERNEL);
135 buffer = kmalloc(rdma->sc_max_req_size, GFP_KERNEL);
138 addr = ib_dma_map_single(rdma->sc_pd->device, buffer,
139 rdma->sc_max_req_size, DMA_FROM_DEVICE);
140 if (ib_dma_mapping_error(rdma->sc_pd->device, addr))
143 svc_rdma_recv_cid_init(rdma, &ctxt->rc_cid);
144 pcl_init(&ctxt->rc_call_pcl);
145 pcl_init(&ctxt->rc_read_pcl);
146 pcl_init(&ctxt->rc_write_pcl);
147 pcl_init(&ctxt->rc_reply_pcl);
149 ctxt->rc_recv_wr.next = NULL;
150 ctxt->rc_recv_wr.wr_cqe = &ctxt->rc_cqe;
151 ctxt->rc_recv_wr.sg_list = &ctxt->rc_recv_sge;
152 ctxt->rc_recv_wr.num_sge = 1;
153 ctxt->rc_cqe.done = svc_rdma_wc_receive;
154 ctxt->rc_recv_sge.addr = addr;
155 ctxt->rc_recv_sge.length = rdma->sc_max_req_size;
156 ctxt->rc_recv_sge.lkey = rdma->sc_pd->local_dma_lkey;
157 ctxt->rc_recv_buf = buffer;
158 ctxt->rc_temp = false;
169 static void svc_rdma_recv_ctxt_destroy(struct svcxprt_rdma *rdma,
170 struct svc_rdma_recv_ctxt *ctxt)
172 ib_dma_unmap_single(rdma->sc_pd->device, ctxt->rc_recv_sge.addr,
173 ctxt->rc_recv_sge.length, DMA_FROM_DEVICE);
174 kfree(ctxt->rc_recv_buf);
179 * svc_rdma_recv_ctxts_destroy - Release all recv_ctxt's for an xprt
180 * @rdma: svcxprt_rdma being torn down
183 void svc_rdma_recv_ctxts_destroy(struct svcxprt_rdma *rdma)
185 struct svc_rdma_recv_ctxt *ctxt;
186 struct llist_node *node;
188 while ((node = llist_del_first(&rdma->sc_recv_ctxts))) {
189 ctxt = llist_entry(node, struct svc_rdma_recv_ctxt, rc_node);
190 svc_rdma_recv_ctxt_destroy(rdma, ctxt);
195 * svc_rdma_recv_ctxt_get - Allocate a recv_ctxt
196 * @rdma: controlling svcxprt_rdma
198 * Returns a recv_ctxt or (rarely) NULL if none are available.
200 struct svc_rdma_recv_ctxt *svc_rdma_recv_ctxt_get(struct svcxprt_rdma *rdma)
202 struct svc_rdma_recv_ctxt *ctxt;
203 struct llist_node *node;
205 node = llist_del_first(&rdma->sc_recv_ctxts);
208 ctxt = llist_entry(node, struct svc_rdma_recv_ctxt, rc_node);
211 ctxt->rc_page_count = 0;
215 ctxt = svc_rdma_recv_ctxt_alloc(rdma);
222 * svc_rdma_recv_ctxt_put - Return recv_ctxt to free list
223 * @rdma: controlling svcxprt_rdma
224 * @ctxt: object to return to the free list
227 void svc_rdma_recv_ctxt_put(struct svcxprt_rdma *rdma,
228 struct svc_rdma_recv_ctxt *ctxt)
230 pcl_free(&ctxt->rc_call_pcl);
231 pcl_free(&ctxt->rc_read_pcl);
232 pcl_free(&ctxt->rc_write_pcl);
233 pcl_free(&ctxt->rc_reply_pcl);
236 llist_add(&ctxt->rc_node, &rdma->sc_recv_ctxts);
238 svc_rdma_recv_ctxt_destroy(rdma, ctxt);
242 * svc_rdma_release_rqst - Release transport-specific per-rqst resources
243 * @rqstp: svc_rqst being released
245 * Ensure that the recv_ctxt is released whether or not a Reply
246 * was sent. For example, the client could close the connection,
247 * or svc_process could drop an RPC, before the Reply is sent.
249 void svc_rdma_release_rqst(struct svc_rqst *rqstp)
251 struct svc_rdma_recv_ctxt *ctxt = rqstp->rq_xprt_ctxt;
252 struct svc_xprt *xprt = rqstp->rq_xprt;
253 struct svcxprt_rdma *rdma =
254 container_of(xprt, struct svcxprt_rdma, sc_xprt);
256 rqstp->rq_xprt_ctxt = NULL;
258 svc_rdma_recv_ctxt_put(rdma, ctxt);
261 static bool svc_rdma_refresh_recvs(struct svcxprt_rdma *rdma,
262 unsigned int wanted, bool temp)
264 const struct ib_recv_wr *bad_wr = NULL;
265 struct svc_rdma_recv_ctxt *ctxt;
266 struct ib_recv_wr *recv_chain;
269 if (test_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags))
274 ctxt = svc_rdma_recv_ctxt_get(rdma);
278 trace_svcrdma_post_recv(ctxt);
279 ctxt->rc_temp = temp;
280 ctxt->rc_recv_wr.next = recv_chain;
281 recv_chain = &ctxt->rc_recv_wr;
282 rdma->sc_pending_recvs++;
287 ret = ib_post_recv(rdma->sc_qp, recv_chain, &bad_wr);
293 trace_svcrdma_rq_post_err(rdma, ret);
295 ctxt = container_of(bad_wr, struct svc_rdma_recv_ctxt,
297 bad_wr = bad_wr->next;
298 svc_rdma_recv_ctxt_put(rdma, ctxt);
300 /* Since we're destroying the xprt, no need to reset
301 * sc_pending_recvs. */
306 * svc_rdma_post_recvs - Post initial set of Recv WRs
307 * @rdma: fresh svcxprt_rdma
309 * Returns true if successful, otherwise false.
311 bool svc_rdma_post_recvs(struct svcxprt_rdma *rdma)
313 return svc_rdma_refresh_recvs(rdma, rdma->sc_max_requests, true);
317 * svc_rdma_wc_receive - Invoked by RDMA provider for each polled Receive WC
318 * @cq: Completion Queue context
319 * @wc: Work Completion object
322 static void svc_rdma_wc_receive(struct ib_cq *cq, struct ib_wc *wc)
324 struct svcxprt_rdma *rdma = cq->cq_context;
325 struct ib_cqe *cqe = wc->wr_cqe;
326 struct svc_rdma_recv_ctxt *ctxt;
328 rdma->sc_pending_recvs--;
330 /* WARNING: Only wc->wr_cqe and wc->status are reliable */
331 ctxt = container_of(cqe, struct svc_rdma_recv_ctxt, rc_cqe);
333 if (wc->status != IB_WC_SUCCESS)
335 trace_svcrdma_wc_recv(wc, &ctxt->rc_cid);
337 /* If receive posting fails, the connection is about to be
338 * lost anyway. The server will not be able to send a reply
339 * for this RPC, and the client will retransmit this RPC
340 * anyway when it reconnects.
342 * Therefore we drop the Receive, even if status was SUCCESS
343 * to reduce the likelihood of replayed requests once the
346 if (rdma->sc_pending_recvs < rdma->sc_max_requests)
347 if (!svc_rdma_refresh_recvs(rdma, rdma->sc_recv_batch, false))
350 /* All wc fields are now known to be valid */
351 ctxt->rc_byte_len = wc->byte_len;
353 spin_lock(&rdma->sc_rq_dto_lock);
354 list_add_tail(&ctxt->rc_list, &rdma->sc_rq_dto_q);
355 /* Note the unlock pairs with the smp_rmb in svc_xprt_ready: */
356 set_bit(XPT_DATA, &rdma->sc_xprt.xpt_flags);
357 spin_unlock(&rdma->sc_rq_dto_lock);
358 if (!test_bit(RDMAXPRT_CONN_PENDING, &rdma->sc_flags))
359 svc_xprt_enqueue(&rdma->sc_xprt);
363 if (wc->status == IB_WC_WR_FLUSH_ERR)
364 trace_svcrdma_wc_recv_flush(wc, &ctxt->rc_cid);
366 trace_svcrdma_wc_recv_err(wc, &ctxt->rc_cid);
368 svc_rdma_recv_ctxt_put(rdma, ctxt);
369 svc_xprt_deferred_close(&rdma->sc_xprt);
373 * svc_rdma_flush_recv_queues - Drain pending Receive work
374 * @rdma: svcxprt_rdma being shut down
377 void svc_rdma_flush_recv_queues(struct svcxprt_rdma *rdma)
379 struct svc_rdma_recv_ctxt *ctxt;
381 while ((ctxt = svc_rdma_next_recv_ctxt(&rdma->sc_rq_dto_q))) {
382 list_del(&ctxt->rc_list);
383 svc_rdma_recv_ctxt_put(rdma, ctxt);
387 static void svc_rdma_build_arg_xdr(struct svc_rqst *rqstp,
388 struct svc_rdma_recv_ctxt *ctxt)
390 struct xdr_buf *arg = &rqstp->rq_arg;
392 arg->head[0].iov_base = ctxt->rc_recv_buf;
393 arg->head[0].iov_len = ctxt->rc_byte_len;
394 arg->tail[0].iov_base = NULL;
395 arg->tail[0].iov_len = 0;
398 arg->buflen = ctxt->rc_byte_len;
399 arg->len = ctxt->rc_byte_len;
403 * xdr_count_read_segments - Count number of Read segments in Read list
404 * @rctxt: Ingress receive context
405 * @p: Start of an un-decoded Read list
407 * Before allocating anything, ensure the ingress Read list is safe
410 * The segment count is limited to how many segments can fit in the
411 * transport header without overflowing the buffer. That's about 40
412 * Read segments for a 1KB inline threshold.
415 * %true: Read list is valid. @rctxt's xdr_stream is updated to point
416 * to the first byte past the Read list. rc_read_pcl and
417 * rc_call_pcl cl_count fields are set to the number of
418 * Read segments in the list.
419 * %false: Read list is corrupt. @rctxt's xdr_stream is left in an
422 static bool xdr_count_read_segments(struct svc_rdma_recv_ctxt *rctxt, __be32 *p)
424 rctxt->rc_call_pcl.cl_count = 0;
425 rctxt->rc_read_pcl.cl_count = 0;
426 while (xdr_item_is_present(p)) {
427 u32 position, handle, length;
430 p = xdr_inline_decode(&rctxt->rc_stream,
431 rpcrdma_readseg_maxsz * sizeof(*p));
435 xdr_decode_read_segment(p, &position, &handle,
440 ++rctxt->rc_read_pcl.cl_count;
442 ++rctxt->rc_call_pcl.cl_count;
445 p = xdr_inline_decode(&rctxt->rc_stream, sizeof(*p));
452 /* Sanity check the Read list.
455 * - Read list does not overflow Receive buffer.
456 * - Chunk size limited by largest NFS data payload.
459 * %true: Read list is valid. @rctxt's xdr_stream is updated
460 * to point to the first byte past the Read list.
461 * %false: Read list is corrupt. @rctxt's xdr_stream is left
462 * in an unknown state.
464 static bool xdr_check_read_list(struct svc_rdma_recv_ctxt *rctxt)
468 p = xdr_inline_decode(&rctxt->rc_stream, sizeof(*p));
471 if (!xdr_count_read_segments(rctxt, p))
473 if (!pcl_alloc_call(rctxt, p))
475 return pcl_alloc_read(rctxt, p);
478 static bool xdr_check_write_chunk(struct svc_rdma_recv_ctxt *rctxt)
483 if (xdr_stream_decode_u32(&rctxt->rc_stream, &segcount))
486 /* A bogus segcount causes this buffer overflow check to fail. */
487 p = xdr_inline_decode(&rctxt->rc_stream,
488 segcount * rpcrdma_segment_maxsz * sizeof(*p));
493 * xdr_count_write_chunks - Count number of Write chunks in Write list
494 * @rctxt: Received header and decoding state
495 * @p: start of an un-decoded Write list
497 * Before allocating anything, ensure the ingress Write list is
501 * %true: Write list is valid. @rctxt's xdr_stream is updated
502 * to point to the first byte past the Write list, and
503 * the number of Write chunks is in rc_write_pcl.cl_count.
504 * %false: Write list is corrupt. @rctxt's xdr_stream is left
505 * in an indeterminate state.
507 static bool xdr_count_write_chunks(struct svc_rdma_recv_ctxt *rctxt, __be32 *p)
509 rctxt->rc_write_pcl.cl_count = 0;
510 while (xdr_item_is_present(p)) {
511 if (!xdr_check_write_chunk(rctxt))
513 ++rctxt->rc_write_pcl.cl_count;
514 p = xdr_inline_decode(&rctxt->rc_stream, sizeof(*p));
521 /* Sanity check the Write list.
523 * Implementation limits:
524 * - This implementation currently supports only one Write chunk.
527 * - Write list does not overflow Receive buffer.
528 * - Chunk size limited by largest NFS data payload.
531 * %true: Write list is valid. @rctxt's xdr_stream is updated
532 * to point to the first byte past the Write list.
533 * %false: Write list is corrupt. @rctxt's xdr_stream is left
534 * in an unknown state.
536 static bool xdr_check_write_list(struct svc_rdma_recv_ctxt *rctxt)
540 p = xdr_inline_decode(&rctxt->rc_stream, sizeof(*p));
543 if (!xdr_count_write_chunks(rctxt, p))
545 if (!pcl_alloc_write(rctxt, &rctxt->rc_write_pcl, p))
548 rctxt->rc_cur_result_payload = pcl_first_chunk(&rctxt->rc_write_pcl);
552 /* Sanity check the Reply chunk.
555 * - Reply chunk does not overflow Receive buffer.
556 * - Chunk size limited by largest NFS data payload.
559 * %true: Reply chunk is valid. @rctxt's xdr_stream is updated
560 * to point to the first byte past the Reply chunk.
561 * %false: Reply chunk is corrupt. @rctxt's xdr_stream is left
562 * in an unknown state.
564 static bool xdr_check_reply_chunk(struct svc_rdma_recv_ctxt *rctxt)
568 p = xdr_inline_decode(&rctxt->rc_stream, sizeof(*p));
572 if (!xdr_item_is_present(p))
574 if (!xdr_check_write_chunk(rctxt))
577 rctxt->rc_reply_pcl.cl_count = 1;
578 return pcl_alloc_write(rctxt, &rctxt->rc_reply_pcl, p);
581 /* RPC-over-RDMA Version One private extension: Remote Invalidation.
582 * Responder's choice: requester signals it can handle Send With
583 * Invalidate, and responder chooses one R_key to invalidate.
585 * If there is exactly one distinct R_key in the received transport
586 * header, set rc_inv_rkey to that R_key. Otherwise, set it to zero.
588 static void svc_rdma_get_inv_rkey(struct svcxprt_rdma *rdma,
589 struct svc_rdma_recv_ctxt *ctxt)
591 struct svc_rdma_segment *segment;
592 struct svc_rdma_chunk *chunk;
595 ctxt->rc_inv_rkey = 0;
597 if (!rdma->sc_snd_w_inv)
601 pcl_for_each_chunk(chunk, &ctxt->rc_call_pcl) {
602 pcl_for_each_segment(segment, chunk) {
604 inv_rkey = segment->rs_handle;
605 else if (inv_rkey != segment->rs_handle)
609 pcl_for_each_chunk(chunk, &ctxt->rc_read_pcl) {
610 pcl_for_each_segment(segment, chunk) {
612 inv_rkey = segment->rs_handle;
613 else if (inv_rkey != segment->rs_handle)
617 pcl_for_each_chunk(chunk, &ctxt->rc_write_pcl) {
618 pcl_for_each_segment(segment, chunk) {
620 inv_rkey = segment->rs_handle;
621 else if (inv_rkey != segment->rs_handle)
625 pcl_for_each_chunk(chunk, &ctxt->rc_reply_pcl) {
626 pcl_for_each_segment(segment, chunk) {
628 inv_rkey = segment->rs_handle;
629 else if (inv_rkey != segment->rs_handle)
633 ctxt->rc_inv_rkey = inv_rkey;
637 * svc_rdma_xdr_decode_req - Decode the transport header
638 * @rq_arg: xdr_buf containing ingress RPC/RDMA message
639 * @rctxt: state of decoding
641 * On entry, xdr->head[0].iov_base points to first byte of the
642 * RPC-over-RDMA transport header.
644 * On successful exit, head[0] points to first byte past the
645 * RPC-over-RDMA header. For RDMA_MSG, this is the RPC message.
647 * The length of the RPC-over-RDMA header is returned.
650 * - The transport header is entirely contained in the head iovec.
652 static int svc_rdma_xdr_decode_req(struct xdr_buf *rq_arg,
653 struct svc_rdma_recv_ctxt *rctxt)
655 __be32 *p, *rdma_argp;
656 unsigned int hdr_len;
658 rdma_argp = rq_arg->head[0].iov_base;
659 xdr_init_decode(&rctxt->rc_stream, rq_arg, rdma_argp, NULL);
661 p = xdr_inline_decode(&rctxt->rc_stream,
662 rpcrdma_fixed_maxsz * sizeof(*p));
666 if (*p != rpcrdma_version)
669 rctxt->rc_msgtype = *p;
670 switch (rctxt->rc_msgtype) {
683 if (!xdr_check_read_list(rctxt))
685 if (!xdr_check_write_list(rctxt))
687 if (!xdr_check_reply_chunk(rctxt))
690 rq_arg->head[0].iov_base = rctxt->rc_stream.p;
691 hdr_len = xdr_stream_pos(&rctxt->rc_stream);
692 rq_arg->head[0].iov_len -= hdr_len;
693 rq_arg->len -= hdr_len;
694 trace_svcrdma_decode_rqst(rctxt, rdma_argp, hdr_len);
698 trace_svcrdma_decode_short_err(rctxt, rq_arg->len);
702 trace_svcrdma_decode_badvers_err(rctxt, rdma_argp);
703 return -EPROTONOSUPPORT;
706 trace_svcrdma_decode_drop_err(rctxt, rdma_argp);
710 trace_svcrdma_decode_badproc_err(rctxt, rdma_argp);
714 trace_svcrdma_decode_parse_err(rctxt, rdma_argp);
718 static void svc_rdma_send_error(struct svcxprt_rdma *rdma,
719 struct svc_rdma_recv_ctxt *rctxt,
722 struct svc_rdma_send_ctxt *sctxt;
724 sctxt = svc_rdma_send_ctxt_get(rdma);
727 svc_rdma_send_error_msg(rdma, sctxt, rctxt, status);
730 /* By convention, backchannel calls arrive via rdma_msg type
731 * messages, and never populate the chunk lists. This makes
732 * the RPC/RDMA header small and fixed in size, so it is
733 * straightforward to check the RPC header's direction field.
735 static bool svc_rdma_is_reverse_direction_reply(struct svc_xprt *xprt,
736 struct svc_rdma_recv_ctxt *rctxt)
738 __be32 *p = rctxt->rc_recv_buf;
740 if (!xprt->xpt_bc_xprt)
743 if (rctxt->rc_msgtype != rdma_msg)
746 if (!pcl_is_empty(&rctxt->rc_call_pcl))
748 if (!pcl_is_empty(&rctxt->rc_read_pcl))
750 if (!pcl_is_empty(&rctxt->rc_write_pcl))
752 if (!pcl_is_empty(&rctxt->rc_reply_pcl))
755 /* RPC call direction */
756 if (*(p + 8) == cpu_to_be32(RPC_CALL))
763 * svc_rdma_recvfrom - Receive an RPC call
764 * @rqstp: request structure into which to receive an RPC Call
767 * The positive number of bytes in the RPC Call message,
768 * %0 if there were no Calls ready to return,
769 * %-EINVAL if the Read chunk data is too large,
770 * %-ENOMEM if rdma_rw context pool was exhausted,
771 * %-ENOTCONN if posting failed (connection is lost),
772 * %-EIO if rdma_rw initialization failed (DMA mapping, etc).
774 * Called in a loop when XPT_DATA is set. XPT_DATA is cleared only
775 * when there are no remaining ctxt's to process.
777 * The next ctxt is removed from the "receive" lists.
779 * - If the ctxt completes a Read, then finish assembling the Call
780 * message and return the number of bytes in the message.
782 * - If the ctxt completes a Receive, then construct the Call
783 * message from the contents of the Receive buffer.
785 * - If there are no Read chunks in this message, then finish
786 * assembling the Call message and return the number of bytes
789 * - If there are Read chunks in this message, post Read WRs to
790 * pull that payload and return 0.
792 int svc_rdma_recvfrom(struct svc_rqst *rqstp)
794 struct svc_xprt *xprt = rqstp->rq_xprt;
795 struct svcxprt_rdma *rdma_xprt =
796 container_of(xprt, struct svcxprt_rdma, sc_xprt);
797 struct svc_rdma_recv_ctxt *ctxt;
800 rqstp->rq_xprt_ctxt = NULL;
803 spin_lock(&rdma_xprt->sc_rq_dto_lock);
804 ctxt = svc_rdma_next_recv_ctxt(&rdma_xprt->sc_rq_dto_q);
806 list_del(&ctxt->rc_list);
808 /* No new incoming requests, terminate the loop */
809 clear_bit(XPT_DATA, &xprt->xpt_flags);
810 spin_unlock(&rdma_xprt->sc_rq_dto_lock);
812 /* Unblock the transport for the next receive */
813 svc_xprt_received(xprt);
817 percpu_counter_inc(&svcrdma_stat_recv);
818 ib_dma_sync_single_for_cpu(rdma_xprt->sc_pd->device,
819 ctxt->rc_recv_sge.addr, ctxt->rc_byte_len,
821 svc_rdma_build_arg_xdr(rqstp, ctxt);
823 /* Prevent svc_xprt_release from releasing pages in rq_pages
824 * if we return 0 or an error.
826 rqstp->rq_respages = rqstp->rq_pages;
827 rqstp->rq_next_page = rqstp->rq_respages;
829 ret = svc_rdma_xdr_decode_req(&rqstp->rq_arg, ctxt);
835 if (svc_rdma_is_reverse_direction_reply(xprt, ctxt))
836 goto out_backchannel;
838 svc_rdma_get_inv_rkey(rdma_xprt, ctxt);
840 if (!pcl_is_empty(&ctxt->rc_read_pcl) ||
841 !pcl_is_empty(&ctxt->rc_call_pcl)) {
842 ret = svc_rdma_process_read_list(rdma_xprt, rqstp, ctxt);
847 rqstp->rq_xprt_ctxt = ctxt;
848 rqstp->rq_prot = IPPROTO_MAX;
849 svc_xprt_copy_addrs(rqstp, xprt);
850 return rqstp->rq_arg.len;
853 svc_rdma_send_error(rdma_xprt, ctxt, ret);
854 svc_rdma_recv_ctxt_put(rdma_xprt, ctxt);
859 svc_rdma_send_error(rdma_xprt, ctxt, ret);
860 svc_rdma_recv_ctxt_put(rdma_xprt, ctxt);
864 svc_rdma_handle_bc_reply(rqstp, ctxt);
866 svc_rdma_recv_ctxt_put(rdma_xprt, ctxt);