1// SPDX-License-Identifier: GPL-2.0 2/* 3 * Copyright (c) 2015-2018 Oracle. All rights reserved. 4 * 5 * Support for backward direction RPCs on RPC/RDMA (server-side). 6 */ 7 8#include <linux/sunrpc/svc_rdma.h> 9 10#include "xprt_rdma.h" 11#include <trace/events/rpcrdma.h> 12 13/** 14 * svc_rdma_handle_bc_reply - Process incoming backchannel Reply 15 * @rqstp: resources for handling the Reply 16 * @rctxt: Received message 17 * 18 */ 19void svc_rdma_handle_bc_reply(struct svc_rqst *rqstp, 20 struct svc_rdma_recv_ctxt *rctxt) 21{ 22 struct svc_xprt *sxprt = rqstp->rq_xprt; 23 struct rpc_xprt *xprt = sxprt->xpt_bc_xprt; 24 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); 25 struct xdr_buf *rcvbuf = &rqstp->rq_arg; 26 struct kvec *dst, *src = &rcvbuf->head[0]; 27 __be32 *rdma_resp = rctxt->rc_recv_buf; 28 struct rpc_rqst *req; 29 u32 credits; 30 31 spin_lock(&xprt->queue_lock); 32 req = xprt_lookup_rqst(xprt, *rdma_resp); 33 if (!req) 34 goto out_unlock; 35 36 dst = &req->rq_private_buf.head[0]; 37 memcpy(&req->rq_private_buf, &req->rq_rcv_buf, sizeof(struct xdr_buf)); 38 if (dst->iov_len < src->iov_len) 39 goto out_unlock; 40 memcpy(dst->iov_base, src->iov_base, src->iov_len); 41 xprt_pin_rqst(req); 42 spin_unlock(&xprt->queue_lock); 43 44 credits = be32_to_cpup(rdma_resp + 2); 45 if (credits == 0) 46 credits = 1; /* don't deadlock */ 47 else if (credits > r_xprt->rx_buf.rb_bc_max_requests) 48 credits = r_xprt->rx_buf.rb_bc_max_requests; 49 spin_lock(&xprt->transport_lock); 50 xprt->cwnd = credits << RPC_CWNDSHIFT; 51 spin_unlock(&xprt->transport_lock); 52 53 spin_lock(&xprt->queue_lock); 54 xprt_complete_rqst(req->rq_task, rcvbuf->len); 55 xprt_unpin_rqst(req); 56 rcvbuf->len = 0; 57 58out_unlock: 59 spin_unlock(&xprt->queue_lock); 60} 61 62/* Send a backwards direction RPC call. 63 * 64 * Caller holds the connection's mutex and has already marshaled 65 * the RPC/RDMA request. 66 * 67 * This is similar to svc_rdma_send_reply_msg, but takes a struct 68 * rpc_rqst instead, does not support chunks, and avoids blocking 69 * memory allocation. 70 * 71 * XXX: There is still an opportunity to block in svc_rdma_send() 72 * if there are no SQ entries to post the Send. This may occur if 73 * the adapter has a small maximum SQ depth. 74 */ 75static int svc_rdma_bc_sendto(struct svcxprt_rdma *rdma, 76 struct rpc_rqst *rqst, 77 struct svc_rdma_send_ctxt *ctxt) 78{ 79 int ret; 80 81 ret = svc_rdma_map_reply_msg(rdma, ctxt, NULL, &rqst->rq_snd_buf); 82 if (ret < 0) 83 return -EIO; 84 85 /* Bump page refcnt so Send completion doesn't release 86 * the rq_buffer before all retransmits are complete. 87 */ 88 get_page(virt_to_page(rqst->rq_buffer)); 89 ctxt->sc_send_wr.opcode = IB_WR_SEND; 90 return svc_rdma_send(rdma, ctxt); 91} 92 93/* Server-side transport endpoint wants a whole page for its send 94 * buffer. The client RPC code constructs the RPC header in this 95 * buffer before it invokes ->send_request. 96 */ 97static int 98xprt_rdma_bc_allocate(struct rpc_task *task) 99{ 100 struct rpc_rqst *rqst = task->tk_rqstp; 101 size_t size = rqst->rq_callsize; 102 struct page *page; 103 104 if (size > PAGE_SIZE) { 105 WARN_ONCE(1, "svcrdma: large bc buffer request (size %zu)\n", 106 size); 107 return -EINVAL; 108 } 109 110 page = alloc_page(RPCRDMA_DEF_GFP); 111 if (!page) 112 return -ENOMEM; 113 rqst->rq_buffer = page_address(page); 114 115 rqst->rq_rbuffer = kmalloc(rqst->rq_rcvsize, RPCRDMA_DEF_GFP); 116 if (!rqst->rq_rbuffer) { 117 put_page(page); 118 return -ENOMEM; 119 } 120 return 0; 121} 122 123static void 124xprt_rdma_bc_free(struct rpc_task *task) 125{ 126 struct rpc_rqst *rqst = task->tk_rqstp; 127 128 put_page(virt_to_page(rqst->rq_buffer)); 129 kfree(rqst->rq_rbuffer); 130} 131 132static int 133rpcrdma_bc_send_request(struct svcxprt_rdma *rdma, struct rpc_rqst *rqst) 134{ 135 struct rpc_xprt *xprt = rqst->rq_xprt; 136 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); 137 struct svc_rdma_send_ctxt *ctxt; 138 __be32 *p; 139 int rc; 140 141 ctxt = svc_rdma_send_ctxt_get(rdma); 142 if (!ctxt) 143 goto drop_connection; 144 145 p = xdr_reserve_space(&ctxt->sc_stream, RPCRDMA_HDRLEN_MIN); 146 if (!p) 147 goto put_ctxt; 148 *p++ = rqst->rq_xid; 149 *p++ = rpcrdma_version; 150 *p++ = cpu_to_be32(r_xprt->rx_buf.rb_bc_max_requests); 151 *p++ = rdma_msg; 152 *p++ = xdr_zero; 153 *p++ = xdr_zero; 154 *p = xdr_zero; 155 156 rqst->rq_xtime = ktime_get(); 157 rc = svc_rdma_bc_sendto(rdma, rqst, ctxt); 158 if (rc) 159 goto put_ctxt; 160 return 0; 161 162put_ctxt: 163 svc_rdma_send_ctxt_put(rdma, ctxt); 164 165drop_connection: 166 return -ENOTCONN; 167} 168 169/** 170 * xprt_rdma_bc_send_request - Send a reverse-direction Call 171 * @rqst: rpc_rqst containing Call message to be sent 172 * 173 * Return values: 174 * %0 if the message was sent successfully 175 * %ENOTCONN if the message was not sent 176 */ 177static int xprt_rdma_bc_send_request(struct rpc_rqst *rqst) 178{ 179 struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt; 180 struct svcxprt_rdma *rdma = 181 container_of(sxprt, struct svcxprt_rdma, sc_xprt); 182 int ret; 183 184 if (test_bit(XPT_DEAD, &sxprt->xpt_flags)) 185 return -ENOTCONN; 186 187 ret = rpcrdma_bc_send_request(rdma, rqst); 188 if (ret == -ENOTCONN) 189 svc_close_xprt(sxprt); 190 return ret; 191} 192 193static void 194xprt_rdma_bc_close(struct rpc_xprt *xprt) 195{ 196 xprt_disconnect_done(xprt); 197 xprt->cwnd = RPC_CWNDSHIFT; 198} 199 200static void 201xprt_rdma_bc_put(struct rpc_xprt *xprt) 202{ 203 xprt_rdma_free_addresses(xprt); 204 xprt_free(xprt); 205} 206 207static const struct rpc_xprt_ops xprt_rdma_bc_procs = { 208 .reserve_xprt = xprt_reserve_xprt_cong, 209 .release_xprt = xprt_release_xprt_cong, 210 .alloc_slot = xprt_alloc_slot, 211 .free_slot = xprt_free_slot, 212 .release_request = xprt_release_rqst_cong, 213 .buf_alloc = xprt_rdma_bc_allocate, 214 .buf_free = xprt_rdma_bc_free, 215 .send_request = xprt_rdma_bc_send_request, 216 .wait_for_reply_request = xprt_wait_for_reply_request_def, 217 .close = xprt_rdma_bc_close, 218 .destroy = xprt_rdma_bc_put, 219 .print_stats = xprt_rdma_print_stats 220}; 221 222static const struct rpc_timeout xprt_rdma_bc_timeout = { 223 .to_initval = 60 * HZ, 224 .to_maxval = 60 * HZ, 225}; 226 227/* It shouldn't matter if the number of backchannel session slots 228 * doesn't match the number of RPC/RDMA credits. That just means 229 * one or the other will have extra slots that aren't used. 230 */ 231static struct rpc_xprt * 232xprt_setup_rdma_bc(struct xprt_create *args) 233{ 234 struct rpc_xprt *xprt; 235 struct rpcrdma_xprt *new_xprt; 236 237 if (args->addrlen > sizeof(xprt->addr)) 238 return ERR_PTR(-EBADF); 239 240 xprt = xprt_alloc(args->net, sizeof(*new_xprt), 241 RPCRDMA_MAX_BC_REQUESTS, 242 RPCRDMA_MAX_BC_REQUESTS); 243 if (!xprt) 244 return ERR_PTR(-ENOMEM); 245 246 xprt->timeout = &xprt_rdma_bc_timeout; 247 xprt_set_bound(xprt); 248 xprt_set_connected(xprt); 249 xprt->bind_timeout = 0; 250 xprt->reestablish_timeout = 0; 251 xprt->idle_timeout = 0; 252 253 xprt->prot = XPRT_TRANSPORT_BC_RDMA; 254 xprt->ops = &xprt_rdma_bc_procs; 255 256 memcpy(&xprt->addr, args->dstaddr, args->addrlen); 257 xprt->addrlen = args->addrlen; 258 xprt_rdma_format_addresses(xprt, (struct sockaddr *)&xprt->addr); 259 xprt->resvport = 0; 260 261 xprt->max_payload = xprt_rdma_max_inline_read; 262 263 new_xprt = rpcx_to_rdmax(xprt); 264 new_xprt->rx_buf.rb_bc_max_requests = xprt->max_reqs; 265 266 xprt_get(xprt); 267 args->bc_xprt->xpt_bc_xprt = xprt; 268 xprt->bc_xprt = args->bc_xprt; 269 270 /* Final put for backchannel xprt is in __svc_rdma_free */ 271 xprt_get(xprt); 272 return xprt; 273} 274 275struct xprt_class xprt_rdma_bc = { 276 .list = LIST_HEAD_INIT(xprt_rdma_bc.list), 277 .name = "rdma backchannel", 278 .owner = THIS_MODULE, 279 .ident = XPRT_TRANSPORT_BC_RDMA, 280 .setup = xprt_setup_rdma_bc, 281}; 282