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 */
svc_rdma_handle_bc_reply(struct rpc_xprt * xprt,__be32 * rdma_resp,struct xdr_buf * rcvbuf)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->recv_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->recv_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 */
svc_rdma_bc_sendto(struct svcxprt_rdma * rdma,struct rpc_rqst * rqst,struct svc_rdma_send_ctxt * ctxt)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
xprt_rdma_bc_allocate(struct rpc_task * task)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
xprt_rdma_bc_free(struct rpc_task * task)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
rpcrdma_bc_send_request(struct svcxprt_rdma * rdma,struct rpc_rqst * rqst)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
xprt_rdma_bc_send_request(struct rpc_task * task)218 xprt_rdma_bc_send_request(struct rpc_task *task)
219 {
220 struct rpc_rqst *rqst = task->tk_rqstp;
221 struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt;
222 struct svcxprt_rdma *rdma;
223 int ret;
224
225 dprintk("svcrdma: sending bc call with xid: %08x\n",
226 be32_to_cpu(rqst->rq_xid));
227
228 if (!mutex_trylock(&sxprt->xpt_mutex)) {
229 rpc_sleep_on(&sxprt->xpt_bc_pending, task, NULL);
230 if (!mutex_trylock(&sxprt->xpt_mutex))
231 return -EAGAIN;
232 rpc_wake_up_queued_task(&sxprt->xpt_bc_pending, task);
233 }
234
235 ret = -ENOTCONN;
236 rdma = container_of(sxprt, struct svcxprt_rdma, sc_xprt);
237 if (!test_bit(XPT_DEAD, &sxprt->xpt_flags))
238 ret = rpcrdma_bc_send_request(rdma, rqst);
239
240 mutex_unlock(&sxprt->xpt_mutex);
241
242 if (ret < 0)
243 return ret;
244 return 0;
245 }
246
247 static void
xprt_rdma_bc_close(struct rpc_xprt * xprt)248 xprt_rdma_bc_close(struct rpc_xprt *xprt)
249 {
250 dprintk("svcrdma: %s: xprt %p\n", __func__, xprt);
251 }
252
253 static void
xprt_rdma_bc_put(struct rpc_xprt * xprt)254 xprt_rdma_bc_put(struct rpc_xprt *xprt)
255 {
256 dprintk("svcrdma: %s: xprt %p\n", __func__, xprt);
257
258 xprt_free(xprt);
259 module_put(THIS_MODULE);
260 }
261
262 static const struct rpc_xprt_ops xprt_rdma_bc_procs = {
263 .reserve_xprt = xprt_reserve_xprt_cong,
264 .release_xprt = xprt_release_xprt_cong,
265 .alloc_slot = xprt_alloc_slot,
266 .free_slot = xprt_free_slot,
267 .release_request = xprt_release_rqst_cong,
268 .buf_alloc = xprt_rdma_bc_allocate,
269 .buf_free = xprt_rdma_bc_free,
270 .send_request = xprt_rdma_bc_send_request,
271 .set_retrans_timeout = xprt_set_retrans_timeout_def,
272 .close = xprt_rdma_bc_close,
273 .destroy = xprt_rdma_bc_put,
274 .print_stats = xprt_rdma_print_stats
275 };
276
277 static const struct rpc_timeout xprt_rdma_bc_timeout = {
278 .to_initval = 60 * HZ,
279 .to_maxval = 60 * HZ,
280 };
281
282 /* It shouldn't matter if the number of backchannel session slots
283 * doesn't match the number of RPC/RDMA credits. That just means
284 * one or the other will have extra slots that aren't used.
285 */
286 static struct rpc_xprt *
xprt_setup_rdma_bc(struct xprt_create * args)287 xprt_setup_rdma_bc(struct xprt_create *args)
288 {
289 struct rpc_xprt *xprt;
290 struct rpcrdma_xprt *new_xprt;
291
292 if (args->addrlen > sizeof(xprt->addr)) {
293 dprintk("RPC: %s: address too large\n", __func__);
294 return ERR_PTR(-EBADF);
295 }
296
297 xprt = xprt_alloc(args->net, sizeof(*new_xprt),
298 RPCRDMA_MAX_BC_REQUESTS,
299 RPCRDMA_MAX_BC_REQUESTS);
300 if (!xprt) {
301 dprintk("RPC: %s: couldn't allocate rpc_xprt\n",
302 __func__);
303 return ERR_PTR(-ENOMEM);
304 }
305
306 xprt->timeout = &xprt_rdma_bc_timeout;
307 xprt_set_bound(xprt);
308 xprt_set_connected(xprt);
309 xprt->bind_timeout = RPCRDMA_BIND_TO;
310 xprt->reestablish_timeout = RPCRDMA_INIT_REEST_TO;
311 xprt->idle_timeout = RPCRDMA_IDLE_DISC_TO;
312
313 xprt->prot = XPRT_TRANSPORT_BC_RDMA;
314 xprt->tsh_size = 0;
315 xprt->ops = &xprt_rdma_bc_procs;
316
317 memcpy(&xprt->addr, args->dstaddr, args->addrlen);
318 xprt->addrlen = args->addrlen;
319 xprt_rdma_format_addresses(xprt, (struct sockaddr *)&xprt->addr);
320 xprt->resvport = 0;
321
322 xprt->max_payload = xprt_rdma_max_inline_read;
323
324 new_xprt = rpcx_to_rdmax(xprt);
325 new_xprt->rx_buf.rb_bc_max_requests = xprt->max_reqs;
326
327 xprt_get(xprt);
328 args->bc_xprt->xpt_bc_xprt = xprt;
329 xprt->bc_xprt = args->bc_xprt;
330
331 if (!try_module_get(THIS_MODULE))
332 goto out_fail;
333
334 /* Final put for backchannel xprt is in __svc_rdma_free */
335 xprt_get(xprt);
336 return xprt;
337
338 out_fail:
339 xprt_rdma_free_addresses(xprt);
340 args->bc_xprt->xpt_bc_xprt = NULL;
341 args->bc_xprt->xpt_bc_xps = NULL;
342 xprt_put(xprt);
343 xprt_free(xprt);
344 return ERR_PTR(-EINVAL);
345 }
346
347 struct xprt_class xprt_rdma_bc = {
348 .list = LIST_HEAD_INIT(xprt_rdma_bc.list),
349 .name = "rdma backchannel",
350 .owner = THIS_MODULE,
351 .ident = XPRT_TRANSPORT_BC_RDMA,
352 .setup = xprt_setup_rdma_bc,
353 };
354
