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/module.h> 9 10 #include <linux/sunrpc/svc_rdma.h> 11 12 #include "xprt_rdma.h" 13 #include <trace/events/rpcrdma.h> 14 15 #define RPCDBG_FACILITY RPCDBG_SVCXPRT 16 17 #undef SVCRDMA_BACKCHANNEL_DEBUG 18 19 /** 20 * svc_rdma_handle_bc_reply - Process incoming backchannel reply 21 * @xprt: controlling backchannel transport 22 * @rdma_resp: pointer to incoming transport header 23 * @rcvbuf: XDR buffer into which to decode the reply 24 * 25 * Returns: 26 * %0 if @rcvbuf is filled in, xprt_complete_rqst called, 27 * %-EAGAIN if server should call ->recvfrom again. 28 */ 29 int svc_rdma_handle_bc_reply(struct rpc_xprt *xprt, __be32 *rdma_resp, 30 struct xdr_buf *rcvbuf) 31 { 32 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); 33 struct kvec *dst, *src = &rcvbuf->head[0]; 34 struct rpc_rqst *req; 35 unsigned long cwnd; 36 u32 credits; 37 size_t len; 38 __be32 xid; 39 __be32 *p; 40 int ret; 41 42 p = (__be32 *)src->iov_base; 43 len = src->iov_len; 44 xid = *rdma_resp; 45 46 #ifdef SVCRDMA_BACKCHANNEL_DEBUG 47 pr_info("%s: xid=%08x, length=%zu\n", 48 __func__, be32_to_cpu(xid), len); 49 pr_info("%s: RPC/RDMA: %*ph\n", 50 __func__, (int)RPCRDMA_HDRLEN_MIN, rdma_resp); 51 pr_info("%s: RPC: %*ph\n", 52 __func__, (int)len, p); 53 #endif 54 55 ret = -EAGAIN; 56 if (src->iov_len < 24) 57 goto out_shortreply; 58 59 spin_lock(&xprt->queue_lock); 60 req = xprt_lookup_rqst(xprt, xid); 61 if (!req) 62 goto out_notfound; 63 64 dst = &req->rq_private_buf.head[0]; 65 memcpy(&req->rq_private_buf, &req->rq_rcv_buf, sizeof(struct xdr_buf)); 66 if (dst->iov_len < len) 67 goto out_unlock; 68 memcpy(dst->iov_base, p, len); 69 70 credits = be32_to_cpup(rdma_resp + 2); 71 if (credits == 0) 72 credits = 1; /* don't deadlock */ 73 else if (credits > r_xprt->rx_buf.rb_bc_max_requests) 74 credits = r_xprt->rx_buf.rb_bc_max_requests; 75 76 spin_lock_bh(&xprt->transport_lock); 77 cwnd = xprt->cwnd; 78 xprt->cwnd = credits << RPC_CWNDSHIFT; 79 if (xprt->cwnd > cwnd) 80 xprt_release_rqst_cong(req->rq_task); 81 spin_unlock_bh(&xprt->transport_lock); 82 83 84 ret = 0; 85 xprt_complete_rqst(req->rq_task, rcvbuf->len); 86 rcvbuf->len = 0; 87 88 out_unlock: 89 spin_unlock(&xprt->queue_lock); 90 out: 91 return ret; 92 93 out_shortreply: 94 dprintk("svcrdma: short bc reply: xprt=%p, len=%zu\n", 95 xprt, src->iov_len); 96 goto out; 97 98 out_notfound: 99 dprintk("svcrdma: unrecognized bc reply: xprt=%p, xid=%08x\n", 100 xprt, be32_to_cpu(xid)); 101 goto out_unlock; 102 } 103 104 /* Send a backwards direction RPC call. 105 * 106 * Caller holds the connection's mutex and has already marshaled 107 * the RPC/RDMA request. 108 * 109 * This is similar to svc_rdma_send_reply_msg, but takes a struct 110 * rpc_rqst instead, does not support chunks, and avoids blocking 111 * memory allocation. 112 * 113 * XXX: There is still an opportunity to block in svc_rdma_send() 114 * if there are no SQ entries to post the Send. This may occur if 115 * the adapter has a small maximum SQ depth. 116 */ 117 static int svc_rdma_bc_sendto(struct svcxprt_rdma *rdma, 118 struct rpc_rqst *rqst, 119 struct svc_rdma_send_ctxt *ctxt) 120 { 121 int ret; 122 123 ret = svc_rdma_map_reply_msg(rdma, ctxt, &rqst->rq_snd_buf, NULL); 124 if (ret < 0) 125 return -EIO; 126 127 /* Bump page refcnt so Send completion doesn't release 128 * the rq_buffer before all retransmits are complete. 129 */ 130 get_page(virt_to_page(rqst->rq_buffer)); 131 ctxt->sc_send_wr.opcode = IB_WR_SEND; 132 return svc_rdma_send(rdma, &ctxt->sc_send_wr); 133 } 134 135 /* Server-side transport endpoint wants a whole page for its send 136 * buffer. The client RPC code constructs the RPC header in this 137 * buffer before it invokes ->send_request. 138 */ 139 static int 140 xprt_rdma_bc_allocate(struct rpc_task *task) 141 { 142 struct rpc_rqst *rqst = task->tk_rqstp; 143 size_t size = rqst->rq_callsize; 144 struct page *page; 145 146 if (size > PAGE_SIZE) { 147 WARN_ONCE(1, "svcrdma: large bc buffer request (size %zu)\n", 148 size); 149 return -EINVAL; 150 } 151 152 page = alloc_page(RPCRDMA_DEF_GFP); 153 if (!page) 154 return -ENOMEM; 155 rqst->rq_buffer = page_address(page); 156 157 rqst->rq_rbuffer = kmalloc(rqst->rq_rcvsize, RPCRDMA_DEF_GFP); 158 if (!rqst->rq_rbuffer) { 159 put_page(page); 160 return -ENOMEM; 161 } 162 return 0; 163 } 164 165 static void 166 xprt_rdma_bc_free(struct rpc_task *task) 167 { 168 struct rpc_rqst *rqst = task->tk_rqstp; 169 170 put_page(virt_to_page(rqst->rq_buffer)); 171 kfree(rqst->rq_rbuffer); 172 } 173 174 static int 175 rpcrdma_bc_send_request(struct svcxprt_rdma *rdma, struct rpc_rqst *rqst) 176 { 177 struct rpc_xprt *xprt = rqst->rq_xprt; 178 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); 179 struct svc_rdma_send_ctxt *ctxt; 180 __be32 *p; 181 int rc; 182 183 ctxt = svc_rdma_send_ctxt_get(rdma); 184 if (!ctxt) 185 goto drop_connection; 186 187 p = ctxt->sc_xprt_buf; 188 *p++ = rqst->rq_xid; 189 *p++ = rpcrdma_version; 190 *p++ = cpu_to_be32(r_xprt->rx_buf.rb_bc_max_requests); 191 *p++ = rdma_msg; 192 *p++ = xdr_zero; 193 *p++ = xdr_zero; 194 *p = xdr_zero; 195 svc_rdma_sync_reply_hdr(rdma, ctxt, RPCRDMA_HDRLEN_MIN); 196 197 #ifdef SVCRDMA_BACKCHANNEL_DEBUG 198 pr_info("%s: %*ph\n", __func__, 64, rqst->rq_buffer); 199 #endif 200 201 rc = svc_rdma_bc_sendto(rdma, rqst, ctxt); 202 if (rc) { 203 svc_rdma_send_ctxt_put(rdma, ctxt); 204 goto drop_connection; 205 } 206 return rc; 207 208 drop_connection: 209 dprintk("svcrdma: failed to send bc call\n"); 210 xprt_disconnect_done(xprt); 211 return -ENOTCONN; 212 } 213 214 /* Send an RPC call on the passive end of a transport 215 * connection. 216 */ 217 static int 218 xprt_rdma_bc_send_request(struct rpc_rqst *rqst) 219 { 220 struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt; 221 struct svcxprt_rdma *rdma; 222 int ret; 223 224 dprintk("svcrdma: sending bc call with xid: %08x\n", 225 be32_to_cpu(rqst->rq_xid)); 226 227 mutex_lock(&sxprt->xpt_mutex); 228 229 ret = -ENOTCONN; 230 rdma = container_of(sxprt, struct svcxprt_rdma, sc_xprt); 231 if (!test_bit(XPT_DEAD, &sxprt->xpt_flags)) 232 ret = rpcrdma_bc_send_request(rdma, rqst); 233 234 mutex_unlock(&sxprt->xpt_mutex); 235 236 if (ret < 0) 237 return ret; 238 return 0; 239 } 240 241 static void 242 xprt_rdma_bc_close(struct rpc_xprt *xprt) 243 { 244 dprintk("svcrdma: %s: xprt %p\n", __func__, xprt); 245 xprt->cwnd = RPC_CWNDSHIFT; 246 } 247 248 static void 249 xprt_rdma_bc_put(struct rpc_xprt *xprt) 250 { 251 dprintk("svcrdma: %s: xprt %p\n", __func__, xprt); 252 253 xprt_free(xprt); 254 module_put(THIS_MODULE); 255 } 256 257 static const struct rpc_xprt_ops xprt_rdma_bc_procs = { 258 .reserve_xprt = xprt_reserve_xprt_cong, 259 .release_xprt = xprt_release_xprt_cong, 260 .alloc_slot = xprt_alloc_slot, 261 .free_slot = xprt_free_slot, 262 .release_request = xprt_release_rqst_cong, 263 .buf_alloc = xprt_rdma_bc_allocate, 264 .buf_free = xprt_rdma_bc_free, 265 .send_request = xprt_rdma_bc_send_request, 266 .set_retrans_timeout = xprt_set_retrans_timeout_def, 267 .close = xprt_rdma_bc_close, 268 .destroy = xprt_rdma_bc_put, 269 .print_stats = xprt_rdma_print_stats 270 }; 271 272 static const struct rpc_timeout xprt_rdma_bc_timeout = { 273 .to_initval = 60 * HZ, 274 .to_maxval = 60 * HZ, 275 }; 276 277 /* It shouldn't matter if the number of backchannel session slots 278 * doesn't match the number of RPC/RDMA credits. That just means 279 * one or the other will have extra slots that aren't used. 280 */ 281 static struct rpc_xprt * 282 xprt_setup_rdma_bc(struct xprt_create *args) 283 { 284 struct rpc_xprt *xprt; 285 struct rpcrdma_xprt *new_xprt; 286 287 if (args->addrlen > sizeof(xprt->addr)) { 288 dprintk("RPC: %s: address too large\n", __func__); 289 return ERR_PTR(-EBADF); 290 } 291 292 xprt = xprt_alloc(args->net, sizeof(*new_xprt), 293 RPCRDMA_MAX_BC_REQUESTS, 294 RPCRDMA_MAX_BC_REQUESTS); 295 if (!xprt) { 296 dprintk("RPC: %s: couldn't allocate rpc_xprt\n", 297 __func__); 298 return ERR_PTR(-ENOMEM); 299 } 300 301 xprt->timeout = &xprt_rdma_bc_timeout; 302 xprt_set_bound(xprt); 303 xprt_set_connected(xprt); 304 xprt->bind_timeout = RPCRDMA_BIND_TO; 305 xprt->reestablish_timeout = RPCRDMA_INIT_REEST_TO; 306 xprt->idle_timeout = RPCRDMA_IDLE_DISC_TO; 307 308 xprt->prot = XPRT_TRANSPORT_BC_RDMA; 309 xprt->tsh_size = 0; 310 xprt->ops = &xprt_rdma_bc_procs; 311 312 memcpy(&xprt->addr, args->dstaddr, args->addrlen); 313 xprt->addrlen = args->addrlen; 314 xprt_rdma_format_addresses(xprt, (struct sockaddr *)&xprt->addr); 315 xprt->resvport = 0; 316 317 xprt->max_payload = xprt_rdma_max_inline_read; 318 319 new_xprt = rpcx_to_rdmax(xprt); 320 new_xprt->rx_buf.rb_bc_max_requests = xprt->max_reqs; 321 322 xprt_get(xprt); 323 args->bc_xprt->xpt_bc_xprt = xprt; 324 xprt->bc_xprt = args->bc_xprt; 325 326 if (!try_module_get(THIS_MODULE)) 327 goto out_fail; 328 329 /* Final put for backchannel xprt is in __svc_rdma_free */ 330 xprt_get(xprt); 331 return xprt; 332 333 out_fail: 334 xprt_rdma_free_addresses(xprt); 335 args->bc_xprt->xpt_bc_xprt = NULL; 336 args->bc_xprt->xpt_bc_xps = NULL; 337 xprt_put(xprt); 338 xprt_free(xprt); 339 return ERR_PTR(-EINVAL); 340 } 341 342 struct xprt_class xprt_rdma_bc = { 343 .list = LIST_HEAD_INIT(xprt_rdma_bc.list), 344 .name = "rdma backchannel", 345 .owner = THIS_MODULE, 346 .ident = XPRT_TRANSPORT_BC_RDMA, 347 .setup = xprt_setup_rdma_bc, 348 }; 349