net/sunrpc/xprtrdma/svc_rdma_backchannel.c

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