// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause /* * Copyright (c) 2016-2018 Oracle. All rights reserved. * Copyright (c) 2014 Open Grid Computing, Inc. All rights reserved. * Copyright (c) 2005-2006 Network Appliance, Inc. All rights reserved. * * This software is available to you under a choice of one of two * licenses. You may choose to be licensed under the terms of the GNU * General Public License (GPL) Version 2, available from the file * COPYING in the main directory of this source tree, or the BSD-type * license below: * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above * copyright notice, this list of conditions and the following * disclaimer in the documentation and/or other materials provided * with the distribution. * * Neither the name of the Network Appliance, Inc. nor the names of * its contributors may be used to endorse or promote products * derived from this software without specific prior written * permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * * Author: Tom Tucker */ /* Operation * * The main entry point is svc_rdma_recvfrom. This is called from * svc_recv when the transport indicates there is incoming data to * be read. "Data Ready" is signaled when an RDMA Receive completes, * or when a set of RDMA Reads complete. * * An svc_rqst is passed in. This structure contains an array of * free pages (rq_pages) that will contain the incoming RPC message. * * Short messages are moved directly into svc_rqst::rq_arg, and * the RPC Call is ready to be processed by the Upper Layer. * svc_rdma_recvfrom returns the length of the RPC Call message, * completing the reception of the RPC Call. * * However, when an incoming message has Read chunks, * svc_rdma_recvfrom must post RDMA Reads to pull the RPC Call's * data payload from the client. svc_rdma_recvfrom sets up the * RDMA Reads using pages in svc_rqst::rq_pages, which are * transferred to an svc_rdma_recv_ctxt for the duration of the * I/O. svc_rdma_recvfrom then returns zero, since the RPC message * is still not yet ready. * * When the Read chunk payloads have become available on the * server, "Data Ready" is raised again, and svc_recv calls * svc_rdma_recvfrom again. This second call may use a different * svc_rqst than the first one, thus any information that needs * to be preserved across these two calls is kept in an * svc_rdma_recv_ctxt. * * The second call to svc_rdma_recvfrom performs final assembly * of the RPC Call message, using the RDMA Read sink pages kept in * the svc_rdma_recv_ctxt. The xdr_buf is copied from the * svc_rdma_recv_ctxt to the second svc_rqst. The second call returns * the length of the completed RPC Call message. * * Page Management * * Pages under I/O must be transferred from the first svc_rqst to an * svc_rdma_recv_ctxt before the first svc_rdma_recvfrom call returns. * * The first svc_rqst supplies pages for RDMA Reads. These are moved * from rqstp::rq_pages into ctxt::pages. The consumed elements of * the rq_pages array are set to NULL and refilled with the first * svc_rdma_recvfrom call returns. * * During the second svc_rdma_recvfrom call, RDMA Read sink pages * are transferred from the svc_rdma_recv_ctxt to the second svc_rqst. */ #include #include #include #include #include #include #include #include #include #include "xprt_rdma.h" #include static void svc_rdma_wc_receive(struct ib_cq *cq, struct ib_wc *wc); static inline struct svc_rdma_recv_ctxt * svc_rdma_next_recv_ctxt(struct list_head *list) { return list_first_entry_or_null(list, struct svc_rdma_recv_ctxt, rc_list); } static void svc_rdma_recv_cid_init(struct svcxprt_rdma *rdma, struct rpc_rdma_cid *cid) { cid->ci_queue_id = rdma->sc_rq_cq->res.id; cid->ci_completion_id = atomic_inc_return(&rdma->sc_completion_ids); } static struct svc_rdma_recv_ctxt * svc_rdma_recv_ctxt_alloc(struct svcxprt_rdma *rdma) { struct svc_rdma_recv_ctxt *ctxt; dma_addr_t addr; void *buffer; ctxt = kmalloc(sizeof(*ctxt), GFP_KERNEL); if (!ctxt) goto fail0; buffer = kmalloc(rdma->sc_max_req_size, GFP_KERNEL); if (!buffer) goto fail1; addr = ib_dma_map_single(rdma->sc_pd->device, buffer, rdma->sc_max_req_size, DMA_FROM_DEVICE); if (ib_dma_mapping_error(rdma->sc_pd->device, addr)) goto fail2; svc_rdma_recv_cid_init(rdma, &ctxt->rc_cid); pcl_init(&ctxt->rc_call_pcl); pcl_init(&ctxt->rc_read_pcl); pcl_init(&ctxt->rc_write_pcl); pcl_init(&ctxt->rc_reply_pcl); ctxt->rc_recv_wr.next = NULL; ctxt->rc_recv_wr.wr_cqe = &ctxt->rc_cqe; ctxt->rc_recv_wr.sg_list = &ctxt->rc_recv_sge; ctxt->rc_recv_wr.num_sge = 1; ctxt->rc_cqe.done = svc_rdma_wc_receive; ctxt->rc_recv_sge.addr = addr; ctxt->rc_recv_sge.length = rdma->sc_max_req_size; ctxt->rc_recv_sge.lkey = rdma->sc_pd->local_dma_lkey; ctxt->rc_recv_buf = buffer; ctxt->rc_temp = false; return ctxt; fail2: kfree(buffer); fail1: kfree(ctxt); fail0: return NULL; } static void svc_rdma_recv_ctxt_destroy(struct svcxprt_rdma *rdma, struct svc_rdma_recv_ctxt *ctxt) { ib_dma_unmap_single(rdma->sc_pd->device, ctxt->rc_recv_sge.addr, ctxt->rc_recv_sge.length, DMA_FROM_DEVICE); kfree(ctxt->rc_recv_buf); kfree(ctxt); } /** * svc_rdma_recv_ctxts_destroy - Release all recv_ctxt's for an xprt * @rdma: svcxprt_rdma being torn down * */ void svc_rdma_recv_ctxts_destroy(struct svcxprt_rdma *rdma) { struct svc_rdma_recv_ctxt *ctxt; struct llist_node *node; while ((node = llist_del_first(&rdma->sc_recv_ctxts))) { ctxt = llist_entry(node, struct svc_rdma_recv_ctxt, rc_node); svc_rdma_recv_ctxt_destroy(rdma, ctxt); } } /** * svc_rdma_recv_ctxt_get - Allocate a recv_ctxt * @rdma: controlling svcxprt_rdma * * Returns a recv_ctxt or (rarely) NULL if none are available. */ struct svc_rdma_recv_ctxt *svc_rdma_recv_ctxt_get(struct svcxprt_rdma *rdma) { struct svc_rdma_recv_ctxt *ctxt; struct llist_node *node; node = llist_del_first(&rdma->sc_recv_ctxts); if (!node) goto out_empty; ctxt = llist_entry(node, struct svc_rdma_recv_ctxt, rc_node); out: ctxt->rc_page_count = 0; return ctxt; out_empty: ctxt = svc_rdma_recv_ctxt_alloc(rdma); if (!ctxt) return NULL; goto out; } /** * svc_rdma_recv_ctxt_put - Return recv_ctxt to free list * @rdma: controlling svcxprt_rdma * @ctxt: object to return to the free list * */ void svc_rdma_recv_ctxt_put(struct svcxprt_rdma *rdma, struct svc_rdma_recv_ctxt *ctxt) { pcl_free(&ctxt->rc_call_pcl); pcl_free(&ctxt->rc_read_pcl); pcl_free(&ctxt->rc_write_pcl); pcl_free(&ctxt->rc_reply_pcl); if (!ctxt->rc_temp) llist_add(&ctxt->rc_node, &rdma->sc_recv_ctxts); else svc_rdma_recv_ctxt_destroy(rdma, ctxt); } /** * svc_rdma_release_ctxt - Release transport-specific per-rqst resources * @xprt: the transport which owned the context * @vctxt: the context from rqstp->rq_xprt_ctxt or dr->xprt_ctxt * * Ensure that the recv_ctxt is released whether or not a Reply * was sent. For example, the client could close the connection, * or svc_process could drop an RPC, before the Reply is sent. */ void svc_rdma_release_ctxt(struct svc_xprt *xprt, void *vctxt) { struct svc_rdma_recv_ctxt *ctxt = vctxt; struct svcxprt_rdma *rdma = container_of(xprt, struct svcxprt_rdma, sc_xprt); if (ctxt) svc_rdma_recv_ctxt_put(rdma, ctxt); } static bool svc_rdma_refresh_recvs(struct svcxprt_rdma *rdma, unsigned int wanted, bool temp) { const struct ib_recv_wr *bad_wr = NULL; struct svc_rdma_recv_ctxt *ctxt; struct ib_recv_wr *recv_chain; int ret; if (test_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags)) return false; recv_chain = NULL; while (wanted--) { ctxt = svc_rdma_recv_ctxt_get(rdma); if (!ctxt) break; trace_svcrdma_post_recv(ctxt); ctxt->rc_temp = temp; ctxt->rc_recv_wr.next = recv_chain; recv_chain = &ctxt->rc_recv_wr; rdma->sc_pending_recvs++; } if (!recv_chain) return false; ret = ib_post_recv(rdma->sc_qp, recv_chain, &bad_wr); if (ret) goto err_free; return true; err_free: trace_svcrdma_rq_post_err(rdma, ret); while (bad_wr) { ctxt = container_of(bad_wr, struct svc_rdma_recv_ctxt, rc_recv_wr); bad_wr = bad_wr->next; svc_rdma_recv_ctxt_put(rdma, ctxt); } /* Since we're destroying the xprt, no need to reset * sc_pending_recvs. */ return false; } /** * svc_rdma_post_recvs - Post initial set of Recv WRs * @rdma: fresh svcxprt_rdma * * Returns true if successful, otherwise false. */ bool svc_rdma_post_recvs(struct svcxprt_rdma *rdma) { return svc_rdma_refresh_recvs(rdma, rdma->sc_max_requests, true); } /** * svc_rdma_wc_receive - Invoked by RDMA provider for each polled Receive WC * @cq: Completion Queue context * @wc: Work Completion object * */ static void svc_rdma_wc_receive(struct ib_cq *cq, struct ib_wc *wc) { struct svcxprt_rdma *rdma = cq->cq_context; struct ib_cqe *cqe = wc->wr_cqe; struct svc_rdma_recv_ctxt *ctxt; rdma->sc_pending_recvs--; /* WARNING: Only wc->wr_cqe and wc->status are reliable */ ctxt = container_of(cqe, struct svc_rdma_recv_ctxt, rc_cqe); trace_svcrdma_wc_receive(wc, &ctxt->rc_cid); if (wc->status != IB_WC_SUCCESS) goto flushed; /* If receive posting fails, the connection is about to be * lost anyway. The server will not be able to send a reply * for this RPC, and the client will retransmit this RPC * anyway when it reconnects. * * Therefore we drop the Receive, even if status was SUCCESS * to reduce the likelihood of replayed requests once the * client reconnects. */ if (rdma->sc_pending_recvs < rdma->sc_max_requests) if (!svc_rdma_refresh_recvs(rdma, rdma->sc_recv_batch, false)) goto flushed; /* All wc fields are now known to be valid */ ctxt->rc_byte_len = wc->byte_len; spin_lock(&rdma->sc_rq_dto_lock); list_add_tail(&ctxt->rc_list, &rdma->sc_rq_dto_q); /* Note the unlock pairs with the smp_rmb in svc_xprt_ready: */ set_bit(XPT_DATA, &rdma->sc_xprt.xpt_flags); spin_unlock(&rdma->sc_rq_dto_lock); if (!test_bit(RDMAXPRT_CONN_PENDING, &rdma->sc_flags)) svc_xprt_enqueue(&rdma->sc_xprt); return; flushed: svc_rdma_recv_ctxt_put(rdma, ctxt); svc_xprt_deferred_close(&rdma->sc_xprt); } /** * svc_rdma_flush_recv_queues - Drain pending Receive work * @rdma: svcxprt_rdma being shut down * */ void svc_rdma_flush_recv_queues(struct svcxprt_rdma *rdma) { struct svc_rdma_recv_ctxt *ctxt; while ((ctxt = svc_rdma_next_recv_ctxt(&rdma->sc_rq_dto_q))) { list_del(&ctxt->rc_list); svc_rdma_recv_ctxt_put(rdma, ctxt); } } static void svc_rdma_build_arg_xdr(struct svc_rqst *rqstp, struct svc_rdma_recv_ctxt *ctxt) { struct xdr_buf *arg = &rqstp->rq_arg; arg->head[0].iov_base = ctxt->rc_recv_buf; arg->head[0].iov_len = ctxt->rc_byte_len; arg->tail[0].iov_base = NULL; arg->tail[0].iov_len = 0; arg->page_len = 0; arg->page_base = 0; arg->buflen = ctxt->rc_byte_len; arg->len = ctxt->rc_byte_len; } /** * xdr_count_read_segments - Count number of Read segments in Read list * @rctxt: Ingress receive context * @p: Start of an un-decoded Read list * * Before allocating anything, ensure the ingress Read list is safe * to use. * * The segment count is limited to how many segments can fit in the * transport header without overflowing the buffer. That's about 40 * Read segments for a 1KB inline threshold. * * Return values: * %true: Read list is valid. @rctxt's xdr_stream is updated to point * to the first byte past the Read list. rc_read_pcl and * rc_call_pcl cl_count fields are set to the number of * Read segments in the list. * %false: Read list is corrupt. @rctxt's xdr_stream is left in an * unknown state. */ static bool xdr_count_read_segments(struct svc_rdma_recv_ctxt *rctxt, __be32 *p) { rctxt->rc_call_pcl.cl_count = 0; rctxt->rc_read_pcl.cl_count = 0; while (xdr_item_is_present(p)) { u32 position, handle, length; u64 offset; p = xdr_inline_decode(&rctxt->rc_stream, rpcrdma_readseg_maxsz * sizeof(*p)); if (!p) return false; xdr_decode_read_segment(p, &position, &handle, &length, &offset); if (position) { if (position & 3) return false; ++rctxt->rc_read_pcl.cl_count; } else { ++rctxt->rc_call_pcl.cl_count; } p = xdr_inline_decode(&rctxt->rc_stream, sizeof(*p)); if (!p) return false; } return true; } /* Sanity check the Read list. * * Sanity checks: * - Read list does not overflow Receive buffer. * - Chunk size limited by largest NFS data payload. * * Return values: * %true: Read list is valid. @rctxt's xdr_stream is updated * to point to the first byte past the Read list. * %false: Read list is corrupt. @rctxt's xdr_stream is left * in an unknown state. */ static bool xdr_check_read_list(struct svc_rdma_recv_ctxt *rctxt) { __be32 *p; p = xdr_inline_decode(&rctxt->rc_stream, sizeof(*p)); if (!p) return false; if (!xdr_count_read_segments(rctxt, p)) return false; if (!pcl_alloc_call(rctxt, p)) return false; return pcl_alloc_read(rctxt, p); } static bool xdr_check_write_chunk(struct svc_rdma_recv_ctxt *rctxt) { u32 segcount; __be32 *p; if (xdr_stream_decode_u32(&rctxt->rc_stream, &segcount)) return false; /* A bogus segcount causes this buffer overflow check to fail. */ p = xdr_inline_decode(&rctxt->rc_stream, segcount * rpcrdma_segment_maxsz * sizeof(*p)); return p != NULL; } /** * xdr_count_write_chunks - Count number of Write chunks in Write list * @rctxt: Received header and decoding state * @p: start of an un-decoded Write list * * Before allocating anything, ensure the ingress Write list is * safe to use. * * Return values: * %true: Write list is valid. @rctxt's xdr_stream is updated * to point to the first byte past the Write list, and * the number of Write chunks is in rc_write_pcl.cl_count. * %false: Write list is corrupt. @rctxt's xdr_stream is left * in an indeterminate state. */ static bool xdr_count_write_chunks(struct svc_rdma_recv_ctxt *rctxt, __be32 *p) { rctxt->rc_write_pcl.cl_count = 0; while (xdr_item_is_present(p)) { if (!xdr_check_write_chunk(rctxt)) return false; ++rctxt->rc_write_pcl.cl_count; p = xdr_inline_decode(&rctxt->rc_stream, sizeof(*p)); if (!p) return false; } return true; } /* Sanity check the Write list. * * Implementation limits: * - This implementation currently supports only one Write chunk. * * Sanity checks: * - Write list does not overflow Receive buffer. * - Chunk size limited by largest NFS data payload. * * Return values: * %true: Write list is valid. @rctxt's xdr_stream is updated * to point to the first byte past the Write list. * %false: Write list is corrupt. @rctxt's xdr_stream is left * in an unknown state. */ static bool xdr_check_write_list(struct svc_rdma_recv_ctxt *rctxt) { __be32 *p; p = xdr_inline_decode(&rctxt->rc_stream, sizeof(*p)); if (!p) return false; if (!xdr_count_write_chunks(rctxt, p)) return false; if (!pcl_alloc_write(rctxt, &rctxt->rc_write_pcl, p)) return false; rctxt->rc_cur_result_payload = pcl_first_chunk(&rctxt->rc_write_pcl); return true; } /* Sanity check the Reply chunk. * * Sanity checks: * - Reply chunk does not overflow Receive buffer. * - Chunk size limited by largest NFS data payload. * * Return values: * %true: Reply chunk is valid. @rctxt's xdr_stream is updated * to point to the first byte past the Reply chunk. * %false: Reply chunk is corrupt. @rctxt's xdr_stream is left * in an unknown state. */ static bool xdr_check_reply_chunk(struct svc_rdma_recv_ctxt *rctxt) { __be32 *p; p = xdr_inline_decode(&rctxt->rc_stream, sizeof(*p)); if (!p) return false; if (!xdr_item_is_present(p)) return true; if (!xdr_check_write_chunk(rctxt)) return false; rctxt->rc_reply_pcl.cl_count = 1; return pcl_alloc_write(rctxt, &rctxt->rc_reply_pcl, p); } /* RPC-over-RDMA Version One private extension: Remote Invalidation. * Responder's choice: requester signals it can handle Send With * Invalidate, and responder chooses one R_key to invalidate. * * If there is exactly one distinct R_key in the received transport * header, set rc_inv_rkey to that R_key. Otherwise, set it to zero. */ static void svc_rdma_get_inv_rkey(struct svcxprt_rdma *rdma, struct svc_rdma_recv_ctxt *ctxt) { struct svc_rdma_segment *segment; struct svc_rdma_chunk *chunk; u32 inv_rkey; ctxt->rc_inv_rkey = 0; if (!rdma->sc_snd_w_inv) return; inv_rkey = 0; pcl_for_each_chunk(chunk, &ctxt->rc_call_pcl) { pcl_for_each_segment(segment, chunk) { if (inv_rkey == 0) inv_rkey = segment->rs_handle; else if (inv_rkey != segment->rs_handle) return; } } pcl_for_each_chunk(chunk, &ctxt->rc_read_pcl) { pcl_for_each_segment(segment, chunk) { if (inv_rkey == 0) inv_rkey = segment->rs_handle; else if (inv_rkey != segment->rs_handle) return; } } pcl_for_each_chunk(chunk, &ctxt->rc_write_pcl) { pcl_for_each_segment(segment, chunk) { if (inv_rkey == 0) inv_rkey = segment->rs_handle; else if (inv_rkey != segment->rs_handle) return; } } pcl_for_each_chunk(chunk, &ctxt->rc_reply_pcl) { pcl_for_each_segment(segment, chunk) { if (inv_rkey == 0) inv_rkey = segment->rs_handle; else if (inv_rkey != segment->rs_handle) return; } } ctxt->rc_inv_rkey = inv_rkey; } /** * svc_rdma_xdr_decode_req - Decode the transport header * @rq_arg: xdr_buf containing ingress RPC/RDMA message * @rctxt: state of decoding * * On entry, xdr->head[0].iov_base points to first byte of the * RPC-over-RDMA transport header. * * On successful exit, head[0] points to first byte past the * RPC-over-RDMA header. For RDMA_MSG, this is the RPC message. * * The length of the RPC-over-RDMA header is returned. * * Assumptions: * - The transport header is entirely contained in the head iovec. */ static int svc_rdma_xdr_decode_req(struct xdr_buf *rq_arg, struct svc_rdma_recv_ctxt *rctxt) { __be32 *p, *rdma_argp; unsigned int hdr_len; rdma_argp = rq_arg->head[0].iov_base; xdr_init_decode(&rctxt->rc_stream, rq_arg, rdma_argp, NULL); p = xdr_inline_decode(&rctxt->rc_stream, rpcrdma_fixed_maxsz * sizeof(*p)); if (unlikely(!p)) goto out_short; p++; if (*p != rpcrdma_version) goto out_version; p += 2; rctxt->rc_msgtype = *p; switch (rctxt->rc_msgtype) { case rdma_msg: break; case rdma_nomsg: break; case rdma_done: goto out_drop; case rdma_error: goto out_drop; default: goto out_proc; } if (!xdr_check_read_list(rctxt)) goto out_inval; if (!xdr_check_write_list(rctxt)) goto out_inval; if (!xdr_check_reply_chunk(rctxt)) goto out_inval; rq_arg->head[0].iov_base = rctxt->rc_stream.p; hdr_len = xdr_stream_pos(&rctxt->rc_stream); rq_arg->head[0].iov_len -= hdr_len; rq_arg->len -= hdr_len; trace_svcrdma_decode_rqst(rctxt, rdma_argp, hdr_len); return hdr_len; out_short: trace_svcrdma_decode_short_err(rctxt, rq_arg->len); return -EINVAL; out_version: trace_svcrdma_decode_badvers_err(rctxt, rdma_argp); return -EPROTONOSUPPORT; out_drop: trace_svcrdma_decode_drop_err(rctxt, rdma_argp); return 0; out_proc: trace_svcrdma_decode_badproc_err(rctxt, rdma_argp); return -EINVAL; out_inval: trace_svcrdma_decode_parse_err(rctxt, rdma_argp); return -EINVAL; } static void svc_rdma_send_error(struct svcxprt_rdma *rdma, struct svc_rdma_recv_ctxt *rctxt, int status) { struct svc_rdma_send_ctxt *sctxt; sctxt = svc_rdma_send_ctxt_get(rdma); if (!sctxt) return; svc_rdma_send_error_msg(rdma, sctxt, rctxt, status); } /* By convention, backchannel calls arrive via rdma_msg type * messages, and never populate the chunk lists. This makes * the RPC/RDMA header small and fixed in size, so it is * straightforward to check the RPC header's direction field. */ static bool svc_rdma_is_reverse_direction_reply(struct svc_xprt *xprt, struct svc_rdma_recv_ctxt *rctxt) { __be32 *p = rctxt->rc_recv_buf; if (!xprt->xpt_bc_xprt) return false; if (rctxt->rc_msgtype != rdma_msg) return false; if (!pcl_is_empty(&rctxt->rc_call_pcl)) return false; if (!pcl_is_empty(&rctxt->rc_read_pcl)) return false; if (!pcl_is_empty(&rctxt->rc_write_pcl)) return false; if (!pcl_is_empty(&rctxt->rc_reply_pcl)) return false; /* RPC call direction */ if (*(p + 8) == cpu_to_be32(RPC_CALL)) return false; return true; } /** * svc_rdma_recvfrom - Receive an RPC call * @rqstp: request structure into which to receive an RPC Call * * Returns: * The positive number of bytes in the RPC Call message, * %0 if there were no Calls ready to return, * %-EINVAL if the Read chunk data is too large, * %-ENOMEM if rdma_rw context pool was exhausted, * %-ENOTCONN if posting failed (connection is lost), * %-EIO if rdma_rw initialization failed (DMA mapping, etc). * * Called in a loop when XPT_DATA is set. XPT_DATA is cleared only * when there are no remaining ctxt's to process. * * The next ctxt is removed from the "receive" lists. * * - If the ctxt completes a Read, then finish assembling the Call * message and return the number of bytes in the message. * * - If the ctxt completes a Receive, then construct the Call * message from the contents of the Receive buffer. * * - If there are no Read chunks in this message, then finish * assembling the Call message and return the number of bytes * in the message. * * - If there are Read chunks in this message, post Read WRs to * pull that payload and return 0. */ int svc_rdma_recvfrom(struct svc_rqst *rqstp) { struct svc_xprt *xprt = rqstp->rq_xprt; struct svcxprt_rdma *rdma_xprt = container_of(xprt, struct svcxprt_rdma, sc_xprt); struct svc_rdma_recv_ctxt *ctxt; int ret; /* Prevent svc_xprt_release() from releasing pages in rq_pages * when returning 0 or an error. */ rqstp->rq_respages = rqstp->rq_pages; rqstp->rq_next_page = rqstp->rq_respages; rqstp->rq_xprt_ctxt = NULL; ctxt = NULL; spin_lock(&rdma_xprt->sc_rq_dto_lock); ctxt = svc_rdma_next_recv_ctxt(&rdma_xprt->sc_rq_dto_q); if (ctxt) list_del(&ctxt->rc_list); else /* No new incoming requests, terminate the loop */ clear_bit(XPT_DATA, &xprt->xpt_flags); spin_unlock(&rdma_xprt->sc_rq_dto_lock); /* Unblock the transport for the next receive */ svc_xprt_received(xprt); if (!ctxt) return 0; percpu_counter_inc(&svcrdma_stat_recv); ib_dma_sync_single_for_cpu(rdma_xprt->sc_pd->device, ctxt->rc_recv_sge.addr, ctxt->rc_byte_len, DMA_FROM_DEVICE); svc_rdma_build_arg_xdr(rqstp, ctxt); ret = svc_rdma_xdr_decode_req(&rqstp->rq_arg, ctxt); if (ret < 0) goto out_err; if (ret == 0) goto out_drop; if (svc_rdma_is_reverse_direction_reply(xprt, ctxt)) goto out_backchannel; svc_rdma_get_inv_rkey(rdma_xprt, ctxt); if (!pcl_is_empty(&ctxt->rc_read_pcl) || !pcl_is_empty(&ctxt->rc_call_pcl)) { ret = svc_rdma_process_read_list(rdma_xprt, rqstp, ctxt); if (ret < 0) goto out_readfail; } rqstp->rq_xprt_ctxt = ctxt; rqstp->rq_prot = IPPROTO_MAX; svc_xprt_copy_addrs(rqstp, xprt); return rqstp->rq_arg.len; out_err: svc_rdma_send_error(rdma_xprt, ctxt, ret); svc_rdma_recv_ctxt_put(rdma_xprt, ctxt); return 0; out_readfail: if (ret == -EINVAL) svc_rdma_send_error(rdma_xprt, ctxt, ret); svc_rdma_recv_ctxt_put(rdma_xprt, ctxt); svc_xprt_deferred_close(xprt); return -ENOTCONN; out_backchannel: svc_rdma_handle_bc_reply(rqstp, ctxt); out_drop: svc_rdma_recv_ctxt_put(rdma_xprt, ctxt); return 0; }