// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (c) 2015-2018 Oracle. All rights reserved.
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*
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* Support for backward direction RPCs on RPC/RDMA (server-side).
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*/
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#include <linux/sunrpc/svc_rdma.h>
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#include "xprt_rdma.h"
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#include <trace/events/rpcrdma.h>
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/**
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* svc_rdma_handle_bc_reply - Process incoming backchannel Reply
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* @rqstp: resources for handling the Reply
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* @rctxt: Received message
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*
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*/
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void svc_rdma_handle_bc_reply(struct svc_rqst *rqstp,
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struct svc_rdma_recv_ctxt *rctxt)
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{
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struct svc_xprt *sxprt = rqstp->rq_xprt;
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struct rpc_xprt *xprt = sxprt->xpt_bc_xprt;
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struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
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struct xdr_buf *rcvbuf = &rqstp->rq_arg;
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struct kvec *dst, *src = &rcvbuf->head[0];
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__be32 *rdma_resp = rctxt->rc_recv_buf;
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struct rpc_rqst *req;
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u32 credits;
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spin_lock(&xprt->queue_lock);
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req = xprt_lookup_rqst(xprt, *rdma_resp);
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if (!req)
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goto out_unlock;
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dst = &req->rq_private_buf.head[0];
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memcpy(&req->rq_private_buf, &req->rq_rcv_buf, sizeof(struct xdr_buf));
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if (dst->iov_len < src->iov_len)
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goto out_unlock;
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memcpy(dst->iov_base, src->iov_base, src->iov_len);
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xprt_pin_rqst(req);
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spin_unlock(&xprt->queue_lock);
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credits = be32_to_cpup(rdma_resp + 2);
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if (credits == 0)
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credits = 1; /* don't deadlock */
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else if (credits > r_xprt->rx_buf.rb_bc_max_requests)
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credits = r_xprt->rx_buf.rb_bc_max_requests;
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spin_lock(&xprt->transport_lock);
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xprt->cwnd = credits << RPC_CWNDSHIFT;
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spin_unlock(&xprt->transport_lock);
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spin_lock(&xprt->queue_lock);
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xprt_complete_rqst(req->rq_task, rcvbuf->len);
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xprt_unpin_rqst(req);
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rcvbuf->len = 0;
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out_unlock:
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spin_unlock(&xprt->queue_lock);
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}
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/* Send a backwards direction RPC call.
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*
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* Caller holds the connection's mutex and has already marshaled
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* the RPC/RDMA request.
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*
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* This is similar to svc_rdma_send_reply_msg, but takes a struct
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* rpc_rqst instead, does not support chunks, and avoids blocking
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* memory allocation.
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*
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* XXX: There is still an opportunity to block in svc_rdma_send()
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* if there are no SQ entries to post the Send. This may occur if
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* the adapter has a small maximum SQ depth.
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*/
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static int svc_rdma_bc_sendto(struct svcxprt_rdma *rdma,
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struct rpc_rqst *rqst,
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struct svc_rdma_send_ctxt *ctxt)
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{
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int ret;
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ret = svc_rdma_map_reply_msg(rdma, ctxt, NULL, &rqst->rq_snd_buf);
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if (ret < 0)
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return -EIO;
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/* Bump page refcnt so Send completion doesn't release
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* the rq_buffer before all retransmits are complete.
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*/
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get_page(virt_to_page(rqst->rq_buffer));
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ctxt->sc_send_wr.opcode = IB_WR_SEND;
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return svc_rdma_send(rdma, ctxt);
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}
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/* Server-side transport endpoint wants a whole page for its send
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* buffer. The client RPC code constructs the RPC header in this
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* buffer before it invokes ->send_request.
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*/
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static int
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xprt_rdma_bc_allocate(struct rpc_task *task)
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{
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struct rpc_rqst *rqst = task->tk_rqstp;
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size_t size = rqst->rq_callsize;
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struct page *page;
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if (size > PAGE_SIZE) {
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WARN_ONCE(1, "svcrdma: large bc buffer request (size %zu)\n",
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size);
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return -EINVAL;
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}
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page = alloc_page(RPCRDMA_DEF_GFP);
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if (!page)
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return -ENOMEM;
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rqst->rq_buffer = page_address(page);
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rqst->rq_rbuffer = kmalloc(rqst->rq_rcvsize, RPCRDMA_DEF_GFP);
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if (!rqst->rq_rbuffer) {
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put_page(page);
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return -ENOMEM;
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}
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return 0;
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}
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static void
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xprt_rdma_bc_free(struct rpc_task *task)
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{
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struct rpc_rqst *rqst = task->tk_rqstp;
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put_page(virt_to_page(rqst->rq_buffer));
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kfree(rqst->rq_rbuffer);
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}
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static int
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rpcrdma_bc_send_request(struct svcxprt_rdma *rdma, struct rpc_rqst *rqst)
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{
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struct rpc_xprt *xprt = rqst->rq_xprt;
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struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
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struct svc_rdma_send_ctxt *ctxt;
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__be32 *p;
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int rc;
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ctxt = svc_rdma_send_ctxt_get(rdma);
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if (!ctxt)
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goto drop_connection;
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p = xdr_reserve_space(&ctxt->sc_stream, RPCRDMA_HDRLEN_MIN);
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if (!p)
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goto put_ctxt;
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*p++ = rqst->rq_xid;
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*p++ = rpcrdma_version;
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*p++ = cpu_to_be32(r_xprt->rx_buf.rb_bc_max_requests);
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*p++ = rdma_msg;
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*p++ = xdr_zero;
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*p++ = xdr_zero;
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*p = xdr_zero;
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rqst->rq_xtime = ktime_get();
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rc = svc_rdma_bc_sendto(rdma, rqst, ctxt);
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if (rc)
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goto put_ctxt;
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return 0;
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put_ctxt:
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svc_rdma_send_ctxt_put(rdma, ctxt);
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drop_connection:
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return -ENOTCONN;
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}
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/**
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* xprt_rdma_bc_send_request - Send a reverse-direction Call
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* @rqst: rpc_rqst containing Call message to be sent
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*
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* Return values:
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* %0 if the message was sent successfully
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* %ENOTCONN if the message was not sent
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*/
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static int xprt_rdma_bc_send_request(struct rpc_rqst *rqst)
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{
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struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt;
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struct svcxprt_rdma *rdma =
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container_of(sxprt, struct svcxprt_rdma, sc_xprt);
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int ret;
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if (test_bit(XPT_DEAD, &sxprt->xpt_flags))
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return -ENOTCONN;
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ret = rpcrdma_bc_send_request(rdma, rqst);
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if (ret == -ENOTCONN)
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svc_close_xprt(sxprt);
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return ret;
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}
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static void
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xprt_rdma_bc_close(struct rpc_xprt *xprt)
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{
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xprt_disconnect_done(xprt);
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xprt->cwnd = RPC_CWNDSHIFT;
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}
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static void
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xprt_rdma_bc_put(struct rpc_xprt *xprt)
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{
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xprt_rdma_free_addresses(xprt);
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xprt_free(xprt);
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}
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static const struct rpc_xprt_ops xprt_rdma_bc_procs = {
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.reserve_xprt = xprt_reserve_xprt_cong,
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.release_xprt = xprt_release_xprt_cong,
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.alloc_slot = xprt_alloc_slot,
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.free_slot = xprt_free_slot,
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.release_request = xprt_release_rqst_cong,
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.buf_alloc = xprt_rdma_bc_allocate,
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.buf_free = xprt_rdma_bc_free,
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.send_request = xprt_rdma_bc_send_request,
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.wait_for_reply_request = xprt_wait_for_reply_request_def,
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.close = xprt_rdma_bc_close,
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.destroy = xprt_rdma_bc_put,
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.print_stats = xprt_rdma_print_stats
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};
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static const struct rpc_timeout xprt_rdma_bc_timeout = {
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.to_initval = 60 * HZ,
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.to_maxval = 60 * HZ,
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};
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/* It shouldn't matter if the number of backchannel session slots
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* doesn't match the number of RPC/RDMA credits. That just means
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* one or the other will have extra slots that aren't used.
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*/
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static struct rpc_xprt *
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xprt_setup_rdma_bc(struct xprt_create *args)
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{
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struct rpc_xprt *xprt;
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struct rpcrdma_xprt *new_xprt;
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if (args->addrlen > sizeof(xprt->addr))
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return ERR_PTR(-EBADF);
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xprt = xprt_alloc(args->net, sizeof(*new_xprt),
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RPCRDMA_MAX_BC_REQUESTS,
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RPCRDMA_MAX_BC_REQUESTS);
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if (!xprt)
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return ERR_PTR(-ENOMEM);
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xprt->timeout = &xprt_rdma_bc_timeout;
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xprt_set_bound(xprt);
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xprt_set_connected(xprt);
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xprt->bind_timeout = 0;
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xprt->reestablish_timeout = 0;
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xprt->idle_timeout = 0;
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xprt->prot = XPRT_TRANSPORT_BC_RDMA;
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xprt->ops = &xprt_rdma_bc_procs;
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memcpy(&xprt->addr, args->dstaddr, args->addrlen);
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xprt->addrlen = args->addrlen;
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xprt_rdma_format_addresses(xprt, (struct sockaddr *)&xprt->addr);
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xprt->resvport = 0;
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xprt->max_payload = xprt_rdma_max_inline_read;
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new_xprt = rpcx_to_rdmax(xprt);
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new_xprt->rx_buf.rb_bc_max_requests = xprt->max_reqs;
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xprt_get(xprt);
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args->bc_xprt->xpt_bc_xprt = xprt;
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xprt->bc_xprt = args->bc_xprt;
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/* Final put for backchannel xprt is in __svc_rdma_free */
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xprt_get(xprt);
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return xprt;
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}
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struct xprt_class xprt_rdma_bc = {
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.list = LIST_HEAD_INIT(xprt_rdma_bc.list),
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.name = "rdma backchannel",
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.owner = THIS_MODULE,
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.ident = XPRT_TRANSPORT_BC_RDMA,
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.setup = xprt_setup_rdma_bc,
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};
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