1 /* 2 * Copyright (c) 2015 Oracle. All rights reserved. 3 * 4 * Support for backward direction RPCs on RPC/RDMA (server-side). 5 */ 6 7 #include <linux/module.h> 8 #include <linux/sunrpc/svc_rdma.h> 9 #include "xprt_rdma.h" 10 11 #define RPCDBG_FACILITY RPCDBG_SVCXPRT 12 13 #undef SVCRDMA_BACKCHANNEL_DEBUG 14 15 /** 16 * svc_rdma_handle_bc_reply - Process incoming backchannel reply 17 * @xprt: controlling backchannel transport 18 * @rdma_resp: pointer to incoming transport header 19 * @rcvbuf: XDR buffer into which to decode the reply 20 * 21 * Returns: 22 * %0 if @rcvbuf is filled in, xprt_complete_rqst called, 23 * %-EAGAIN if server should call ->recvfrom again. 24 */ 25 int svc_rdma_handle_bc_reply(struct rpc_xprt *xprt, __be32 *rdma_resp, 26 struct xdr_buf *rcvbuf) 27 { 28 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); 29 struct kvec *dst, *src = &rcvbuf->head[0]; 30 struct rpc_rqst *req; 31 unsigned long cwnd; 32 u32 credits; 33 size_t len; 34 __be32 xid; 35 __be32 *p; 36 int ret; 37 38 p = (__be32 *)src->iov_base; 39 len = src->iov_len; 40 xid = *rdma_resp; 41 42 #ifdef SVCRDMA_BACKCHANNEL_DEBUG 43 pr_info("%s: xid=%08x, length=%zu\n", 44 __func__, be32_to_cpu(xid), len); 45 pr_info("%s: RPC/RDMA: %*ph\n", 46 __func__, (int)RPCRDMA_HDRLEN_MIN, rdma_resp); 47 pr_info("%s: RPC: %*ph\n", 48 __func__, (int)len, p); 49 #endif 50 51 ret = -EAGAIN; 52 if (src->iov_len < 24) 53 goto out_shortreply; 54 55 spin_lock_bh(&xprt->transport_lock); 56 req = xprt_lookup_rqst(xprt, xid); 57 if (!req) 58 goto out_notfound; 59 60 dst = &req->rq_private_buf.head[0]; 61 memcpy(&req->rq_private_buf, &req->rq_rcv_buf, sizeof(struct xdr_buf)); 62 if (dst->iov_len < len) 63 goto out_unlock; 64 memcpy(dst->iov_base, p, len); 65 66 credits = be32_to_cpup(rdma_resp + 2); 67 if (credits == 0) 68 credits = 1; /* don't deadlock */ 69 else if (credits > r_xprt->rx_buf.rb_bc_max_requests) 70 credits = r_xprt->rx_buf.rb_bc_max_requests; 71 72 cwnd = xprt->cwnd; 73 xprt->cwnd = credits << RPC_CWNDSHIFT; 74 if (xprt->cwnd > cwnd) 75 xprt_release_rqst_cong(req->rq_task); 76 77 ret = 0; 78 xprt_complete_rqst(req->rq_task, rcvbuf->len); 79 rcvbuf->len = 0; 80 81 out_unlock: 82 spin_unlock_bh(&xprt->transport_lock); 83 out: 84 return ret; 85 86 out_shortreply: 87 dprintk("svcrdma: short bc reply: xprt=%p, len=%zu\n", 88 xprt, src->iov_len); 89 goto out; 90 91 out_notfound: 92 dprintk("svcrdma: unrecognized bc reply: xprt=%p, xid=%08x\n", 93 xprt, be32_to_cpu(xid)); 94 95 goto out_unlock; 96 } 97 98 /* Send a backwards direction RPC call. 99 * 100 * Caller holds the connection's mutex and has already marshaled 101 * the RPC/RDMA request. 102 * 103 * This is similar to svc_rdma_send_reply_msg, but takes a struct 104 * rpc_rqst instead, does not support chunks, and avoids blocking 105 * memory allocation. 106 * 107 * XXX: There is still an opportunity to block in svc_rdma_send() 108 * if there are no SQ entries to post the Send. This may occur if 109 * the adapter has a small maximum SQ depth. 110 */ 111 static int svc_rdma_bc_sendto(struct svcxprt_rdma *rdma, 112 struct rpc_rqst *rqst) 113 { 114 struct svc_rdma_op_ctxt *ctxt; 115 int ret; 116 117 ctxt = svc_rdma_get_context(rdma); 118 119 /* rpcrdma_bc_send_request builds the transport header and 120 * the backchannel RPC message in the same buffer. Thus only 121 * one SGE is needed to send both. 122 */ 123 ret = svc_rdma_map_reply_hdr(rdma, ctxt, rqst->rq_buffer, 124 rqst->rq_snd_buf.len); 125 if (ret < 0) 126 goto out_err; 127 128 ret = svc_rdma_repost_recv(rdma, GFP_NOIO); 129 if (ret) 130 goto out_err; 131 132 ret = svc_rdma_post_send_wr(rdma, ctxt, 1, 0); 133 if (ret) 134 goto out_unmap; 135 136 out_err: 137 dprintk("svcrdma: %s returns %d\n", __func__, ret); 138 return ret; 139 140 out_unmap: 141 svc_rdma_unmap_dma(ctxt); 142 svc_rdma_put_context(ctxt, 1); 143 ret = -EIO; 144 goto out_err; 145 } 146 147 /* Server-side transport endpoint wants a whole page for its send 148 * buffer. The client RPC code constructs the RPC header in this 149 * buffer before it invokes ->send_request. 150 */ 151 static int 152 xprt_rdma_bc_allocate(struct rpc_task *task) 153 { 154 struct rpc_rqst *rqst = task->tk_rqstp; 155 size_t size = rqst->rq_callsize; 156 struct page *page; 157 158 if (size > PAGE_SIZE) { 159 WARN_ONCE(1, "svcrdma: large bc buffer request (size %zu)\n", 160 size); 161 return -EINVAL; 162 } 163 164 /* svc_rdma_sendto releases this page */ 165 page = alloc_page(RPCRDMA_DEF_GFP); 166 if (!page) 167 return -ENOMEM; 168 rqst->rq_buffer = page_address(page); 169 170 rqst->rq_rbuffer = kmalloc(rqst->rq_rcvsize, RPCRDMA_DEF_GFP); 171 if (!rqst->rq_rbuffer) { 172 put_page(page); 173 return -ENOMEM; 174 } 175 return 0; 176 } 177 178 static void 179 xprt_rdma_bc_free(struct rpc_task *task) 180 { 181 struct rpc_rqst *rqst = task->tk_rqstp; 182 183 kfree(rqst->rq_rbuffer); 184 } 185 186 static int 187 rpcrdma_bc_send_request(struct svcxprt_rdma *rdma, struct rpc_rqst *rqst) 188 { 189 struct rpc_xprt *xprt = rqst->rq_xprt; 190 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); 191 __be32 *p; 192 int rc; 193 194 /* Space in the send buffer for an RPC/RDMA header is reserved 195 * via xprt->tsh_size. 196 */ 197 p = rqst->rq_buffer; 198 *p++ = rqst->rq_xid; 199 *p++ = rpcrdma_version; 200 *p++ = cpu_to_be32(r_xprt->rx_buf.rb_bc_max_requests); 201 *p++ = rdma_msg; 202 *p++ = xdr_zero; 203 *p++ = xdr_zero; 204 *p = xdr_zero; 205 206 #ifdef SVCRDMA_BACKCHANNEL_DEBUG 207 pr_info("%s: %*ph\n", __func__, 64, rqst->rq_buffer); 208 #endif 209 210 rc = svc_rdma_bc_sendto(rdma, rqst); 211 if (rc) 212 goto drop_connection; 213 return rc; 214 215 drop_connection: 216 dprintk("svcrdma: failed to send bc call\n"); 217 xprt_disconnect_done(xprt); 218 return -ENOTCONN; 219 } 220 221 /* Send an RPC call on the passive end of a transport 222 * connection. 223 */ 224 static int 225 xprt_rdma_bc_send_request(struct rpc_task *task) 226 { 227 struct rpc_rqst *rqst = task->tk_rqstp; 228 struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt; 229 struct svcxprt_rdma *rdma; 230 int ret; 231 232 dprintk("svcrdma: sending bc call with xid: %08x\n", 233 be32_to_cpu(rqst->rq_xid)); 234 235 if (!mutex_trylock(&sxprt->xpt_mutex)) { 236 rpc_sleep_on(&sxprt->xpt_bc_pending, task, NULL); 237 if (!mutex_trylock(&sxprt->xpt_mutex)) 238 return -EAGAIN; 239 rpc_wake_up_queued_task(&sxprt->xpt_bc_pending, task); 240 } 241 242 ret = -ENOTCONN; 243 rdma = container_of(sxprt, struct svcxprt_rdma, sc_xprt); 244 if (!test_bit(XPT_DEAD, &sxprt->xpt_flags)) 245 ret = rpcrdma_bc_send_request(rdma, rqst); 246 247 mutex_unlock(&sxprt->xpt_mutex); 248 249 if (ret < 0) 250 return ret; 251 return 0; 252 } 253 254 static void 255 xprt_rdma_bc_close(struct rpc_xprt *xprt) 256 { 257 dprintk("svcrdma: %s: xprt %p\n", __func__, xprt); 258 } 259 260 static void 261 xprt_rdma_bc_put(struct rpc_xprt *xprt) 262 { 263 dprintk("svcrdma: %s: xprt %p\n", __func__, xprt); 264 265 xprt_free(xprt); 266 module_put(THIS_MODULE); 267 } 268 269 static struct rpc_xprt_ops xprt_rdma_bc_procs = { 270 .reserve_xprt = xprt_reserve_xprt_cong, 271 .release_xprt = xprt_release_xprt_cong, 272 .alloc_slot = xprt_alloc_slot, 273 .release_request = xprt_release_rqst_cong, 274 .buf_alloc = xprt_rdma_bc_allocate, 275 .buf_free = xprt_rdma_bc_free, 276 .send_request = xprt_rdma_bc_send_request, 277 .set_retrans_timeout = xprt_set_retrans_timeout_def, 278 .close = xprt_rdma_bc_close, 279 .destroy = xprt_rdma_bc_put, 280 .print_stats = xprt_rdma_print_stats 281 }; 282 283 static const struct rpc_timeout xprt_rdma_bc_timeout = { 284 .to_initval = 60 * HZ, 285 .to_maxval = 60 * HZ, 286 }; 287 288 /* It shouldn't matter if the number of backchannel session slots 289 * doesn't match the number of RPC/RDMA credits. That just means 290 * one or the other will have extra slots that aren't used. 291 */ 292 static struct rpc_xprt * 293 xprt_setup_rdma_bc(struct xprt_create *args) 294 { 295 struct rpc_xprt *xprt; 296 struct rpcrdma_xprt *new_xprt; 297 298 if (args->addrlen > sizeof(xprt->addr)) { 299 dprintk("RPC: %s: address too large\n", __func__); 300 return ERR_PTR(-EBADF); 301 } 302 303 xprt = xprt_alloc(args->net, sizeof(*new_xprt), 304 RPCRDMA_MAX_BC_REQUESTS, 305 RPCRDMA_MAX_BC_REQUESTS); 306 if (!xprt) { 307 dprintk("RPC: %s: couldn't allocate rpc_xprt\n", 308 __func__); 309 return ERR_PTR(-ENOMEM); 310 } 311 312 xprt->timeout = &xprt_rdma_bc_timeout; 313 xprt_set_bound(xprt); 314 xprt_set_connected(xprt); 315 xprt->bind_timeout = RPCRDMA_BIND_TO; 316 xprt->reestablish_timeout = RPCRDMA_INIT_REEST_TO; 317 xprt->idle_timeout = RPCRDMA_IDLE_DISC_TO; 318 319 xprt->prot = XPRT_TRANSPORT_BC_RDMA; 320 xprt->tsh_size = RPCRDMA_HDRLEN_MIN / sizeof(__be32); 321 xprt->ops = &xprt_rdma_bc_procs; 322 323 memcpy(&xprt->addr, args->dstaddr, args->addrlen); 324 xprt->addrlen = args->addrlen; 325 xprt_rdma_format_addresses(xprt, (struct sockaddr *)&xprt->addr); 326 xprt->resvport = 0; 327 328 xprt->max_payload = xprt_rdma_max_inline_read; 329 330 new_xprt = rpcx_to_rdmax(xprt); 331 new_xprt->rx_buf.rb_bc_max_requests = xprt->max_reqs; 332 333 xprt_get(xprt); 334 args->bc_xprt->xpt_bc_xprt = xprt; 335 xprt->bc_xprt = args->bc_xprt; 336 337 if (!try_module_get(THIS_MODULE)) 338 goto out_fail; 339 340 /* Final put for backchannel xprt is in __svc_rdma_free */ 341 xprt_get(xprt); 342 return xprt; 343 344 out_fail: 345 xprt_rdma_free_addresses(xprt); 346 args->bc_xprt->xpt_bc_xprt = NULL; 347 args->bc_xprt->xpt_bc_xps = NULL; 348 xprt_put(xprt); 349 xprt_free(xprt); 350 return ERR_PTR(-EINVAL); 351 } 352 353 struct xprt_class xprt_rdma_bc = { 354 .list = LIST_HEAD_INIT(xprt_rdma_bc.list), 355 .name = "rdma backchannel", 356 .owner = THIS_MODULE, 357 .ident = XPRT_TRANSPORT_BC_RDMA, 358 .setup = xprt_setup_rdma_bc, 359 }; 360