1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (c) 2015 Oracle. All rights reserved. 4 * 5 * Support for backward direction RPCs on RPC/RDMA. 6 */ 7 8 #include <linux/sunrpc/xprt.h> 9 #include <linux/sunrpc/svc.h> 10 #include <linux/sunrpc/svc_xprt.h> 11 #include <linux/sunrpc/svc_rdma.h> 12 13 #include "xprt_rdma.h" 14 #include <trace/events/rpcrdma.h> 15 16 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG) 17 # define RPCDBG_FACILITY RPCDBG_TRANS 18 #endif 19 20 #undef RPCRDMA_BACKCHANNEL_DEBUG 21 22 /** 23 * xprt_rdma_bc_setup - Pre-allocate resources for handling backchannel requests 24 * @xprt: transport associated with these backchannel resources 25 * @reqs: number of concurrent incoming requests to expect 26 * 27 * Returns 0 on success; otherwise a negative errno 28 */ 29 int xprt_rdma_bc_setup(struct rpc_xprt *xprt, unsigned int reqs) 30 { 31 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); 32 33 r_xprt->rx_buf.rb_bc_srv_max_requests = RPCRDMA_BACKWARD_WRS >> 1; 34 trace_xprtrdma_cb_setup(r_xprt, reqs); 35 return 0; 36 } 37 38 /** 39 * xprt_rdma_bc_maxpayload - Return maximum backchannel message size 40 * @xprt: transport 41 * 42 * Returns maximum size, in bytes, of a backchannel message 43 */ 44 size_t xprt_rdma_bc_maxpayload(struct rpc_xprt *xprt) 45 { 46 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); 47 struct rpcrdma_ep *ep = &r_xprt->rx_ep; 48 size_t maxmsg; 49 50 maxmsg = min_t(unsigned int, ep->rep_inline_send, ep->rep_inline_recv); 51 maxmsg = min_t(unsigned int, maxmsg, PAGE_SIZE); 52 return maxmsg - RPCRDMA_HDRLEN_MIN; 53 } 54 55 unsigned int xprt_rdma_bc_max_slots(struct rpc_xprt *xprt) 56 { 57 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); 58 59 return r_xprt->rx_buf.rb_bc_srv_max_requests; 60 } 61 62 static int rpcrdma_bc_marshal_reply(struct rpc_rqst *rqst) 63 { 64 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(rqst->rq_xprt); 65 struct rpcrdma_req *req = rpcr_to_rdmar(rqst); 66 __be32 *p; 67 68 rpcrdma_set_xdrlen(&req->rl_hdrbuf, 0); 69 xdr_init_encode(&req->rl_stream, &req->rl_hdrbuf, 70 rdmab_data(req->rl_rdmabuf), rqst); 71 72 p = xdr_reserve_space(&req->rl_stream, 28); 73 if (unlikely(!p)) 74 return -EIO; 75 *p++ = rqst->rq_xid; 76 *p++ = rpcrdma_version; 77 *p++ = cpu_to_be32(r_xprt->rx_buf.rb_bc_srv_max_requests); 78 *p++ = rdma_msg; 79 *p++ = xdr_zero; 80 *p++ = xdr_zero; 81 *p = xdr_zero; 82 83 if (rpcrdma_prepare_send_sges(r_xprt, req, RPCRDMA_HDRLEN_MIN, 84 &rqst->rq_snd_buf, rpcrdma_noch)) 85 return -EIO; 86 87 trace_xprtrdma_cb_reply(rqst); 88 return 0; 89 } 90 91 /** 92 * xprt_rdma_bc_send_reply - marshal and send a backchannel reply 93 * @rqst: RPC rqst with a backchannel RPC reply in rq_snd_buf 94 * 95 * Caller holds the transport's write lock. 96 * 97 * Returns: 98 * %0 if the RPC message has been sent 99 * %-ENOTCONN if the caller should reconnect and call again 100 * %-EIO if a permanent error occurred and the request was not 101 * sent. Do not try to send this message again. 102 */ 103 int xprt_rdma_bc_send_reply(struct rpc_rqst *rqst) 104 { 105 struct rpc_xprt *xprt = rqst->rq_xprt; 106 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); 107 struct rpcrdma_req *req = rpcr_to_rdmar(rqst); 108 int rc; 109 110 if (!xprt_connected(xprt)) 111 return -ENOTCONN; 112 113 if (!xprt_request_get_cong(xprt, rqst)) 114 return -EBADSLT; 115 116 rc = rpcrdma_bc_marshal_reply(rqst); 117 if (rc < 0) 118 goto failed_marshal; 119 120 if (rpcrdma_ep_post(&r_xprt->rx_ia, &r_xprt->rx_ep, req)) 121 goto drop_connection; 122 return 0; 123 124 failed_marshal: 125 if (rc != -ENOTCONN) 126 return rc; 127 drop_connection: 128 xprt_rdma_close(xprt); 129 return -ENOTCONN; 130 } 131 132 /** 133 * xprt_rdma_bc_destroy - Release resources for handling backchannel requests 134 * @xprt: transport associated with these backchannel resources 135 * @reqs: number of incoming requests to destroy; ignored 136 */ 137 void xprt_rdma_bc_destroy(struct rpc_xprt *xprt, unsigned int reqs) 138 { 139 struct rpc_rqst *rqst, *tmp; 140 141 spin_lock(&xprt->bc_pa_lock); 142 list_for_each_entry_safe(rqst, tmp, &xprt->bc_pa_list, rq_bc_pa_list) { 143 list_del(&rqst->rq_bc_pa_list); 144 spin_unlock(&xprt->bc_pa_lock); 145 146 rpcrdma_req_destroy(rpcr_to_rdmar(rqst)); 147 148 spin_lock(&xprt->bc_pa_lock); 149 } 150 spin_unlock(&xprt->bc_pa_lock); 151 } 152 153 /** 154 * xprt_rdma_bc_free_rqst - Release a backchannel rqst 155 * @rqst: request to release 156 */ 157 void xprt_rdma_bc_free_rqst(struct rpc_rqst *rqst) 158 { 159 struct rpcrdma_req *req = rpcr_to_rdmar(rqst); 160 struct rpc_xprt *xprt = rqst->rq_xprt; 161 162 rpcrdma_recv_buffer_put(req->rl_reply); 163 req->rl_reply = NULL; 164 165 spin_lock(&xprt->bc_pa_lock); 166 list_add_tail(&rqst->rq_bc_pa_list, &xprt->bc_pa_list); 167 spin_unlock(&xprt->bc_pa_lock); 168 } 169 170 static struct rpc_rqst *rpcrdma_bc_rqst_get(struct rpcrdma_xprt *r_xprt) 171 { 172 struct rpc_xprt *xprt = &r_xprt->rx_xprt; 173 struct rpcrdma_req *req; 174 struct rpc_rqst *rqst; 175 size_t size; 176 177 spin_lock(&xprt->bc_pa_lock); 178 rqst = list_first_entry_or_null(&xprt->bc_pa_list, struct rpc_rqst, 179 rq_bc_pa_list); 180 if (!rqst) 181 goto create_req; 182 list_del(&rqst->rq_bc_pa_list); 183 spin_unlock(&xprt->bc_pa_lock); 184 return rqst; 185 186 create_req: 187 spin_unlock(&xprt->bc_pa_lock); 188 189 /* Set a limit to prevent a remote from overrunning our resources. 190 */ 191 if (xprt->bc_alloc_count >= RPCRDMA_BACKWARD_WRS) 192 return NULL; 193 194 size = min_t(size_t, r_xprt->rx_ep.rep_inline_recv, PAGE_SIZE); 195 req = rpcrdma_req_create(r_xprt, size, GFP_KERNEL); 196 if (!req) 197 return NULL; 198 199 xprt->bc_alloc_count++; 200 rqst = &req->rl_slot; 201 rqst->rq_xprt = xprt; 202 __set_bit(RPC_BC_PA_IN_USE, &rqst->rq_bc_pa_state); 203 xdr_buf_init(&rqst->rq_snd_buf, rdmab_data(req->rl_sendbuf), size); 204 return rqst; 205 } 206 207 /** 208 * rpcrdma_bc_receive_call - Handle a backward direction call 209 * @r_xprt: transport receiving the call 210 * @rep: receive buffer containing the call 211 * 212 * Operational assumptions: 213 * o Backchannel credits are ignored, just as the NFS server 214 * forechannel currently does 215 * o The ULP manages a replay cache (eg, NFSv4.1 sessions). 216 * No replay detection is done at the transport level 217 */ 218 void rpcrdma_bc_receive_call(struct rpcrdma_xprt *r_xprt, 219 struct rpcrdma_rep *rep) 220 { 221 struct rpc_xprt *xprt = &r_xprt->rx_xprt; 222 struct svc_serv *bc_serv; 223 struct rpcrdma_req *req; 224 struct rpc_rqst *rqst; 225 struct xdr_buf *buf; 226 size_t size; 227 __be32 *p; 228 229 p = xdr_inline_decode(&rep->rr_stream, 0); 230 size = xdr_stream_remaining(&rep->rr_stream); 231 232 #ifdef RPCRDMA_BACKCHANNEL_DEBUG 233 pr_info("RPC: %s: callback XID %08x, length=%u\n", 234 __func__, be32_to_cpup(p), size); 235 pr_info("RPC: %s: %*ph\n", __func__, size, p); 236 #endif 237 238 rqst = rpcrdma_bc_rqst_get(r_xprt); 239 if (!rqst) 240 goto out_overflow; 241 242 rqst->rq_reply_bytes_recvd = 0; 243 rqst->rq_xid = *p; 244 245 rqst->rq_private_buf.len = size; 246 247 buf = &rqst->rq_rcv_buf; 248 memset(buf, 0, sizeof(*buf)); 249 buf->head[0].iov_base = p; 250 buf->head[0].iov_len = size; 251 buf->len = size; 252 253 /* The receive buffer has to be hooked to the rpcrdma_req 254 * so that it is not released while the req is pointing 255 * to its buffer, and so that it can be reposted after 256 * the Upper Layer is done decoding it. 257 */ 258 req = rpcr_to_rdmar(rqst); 259 req->rl_reply = rep; 260 trace_xprtrdma_cb_call(rqst); 261 262 /* Queue rqst for ULP's callback service */ 263 bc_serv = xprt->bc_serv; 264 spin_lock(&bc_serv->sv_cb_lock); 265 list_add(&rqst->rq_bc_list, &bc_serv->sv_cb_list); 266 spin_unlock(&bc_serv->sv_cb_lock); 267 268 wake_up(&bc_serv->sv_cb_waitq); 269 270 r_xprt->rx_stats.bcall_count++; 271 return; 272 273 out_overflow: 274 pr_warn("RPC/RDMA backchannel overflow\n"); 275 xprt_force_disconnect(xprt); 276 /* This receive buffer gets reposted automatically 277 * when the connection is re-established. 278 */ 279 return; 280 } 281