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 (server-side).
6 */
7
8 #include <linux/module.h>
9 #include <linux/sunrpc/svc_rdma.h>
10 #include "xprt_rdma.h"
11
12 #define RPCDBG_FACILITY RPCDBG_SVCXPRT
13
14 #undef SVCRDMA_BACKCHANNEL_DEBUG
15
16 /**
17 * svc_rdma_handle_bc_reply - Process incoming backchannel reply
18 * @xprt: controlling backchannel transport
19 * @rdma_resp: pointer to incoming transport header
20 * @rcvbuf: XDR buffer into which to decode the reply
21 *
22 * Returns:
23 * %0 if @rcvbuf is filled in, xprt_complete_rqst called,
24 * %-EAGAIN if server should call ->recvfrom again.
25 */
svc_rdma_handle_bc_reply(struct rpc_xprt * xprt,__be32 * rdma_resp,struct xdr_buf * rcvbuf)26 int svc_rdma_handle_bc_reply(struct rpc_xprt *xprt, __be32 *rdma_resp,
27 struct xdr_buf *rcvbuf)
28 {
29 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
30 struct kvec *dst, *src = &rcvbuf->head[0];
31 struct rpc_rqst *req;
32 unsigned long cwnd;
33 u32 credits;
34 size_t len;
35 __be32 xid;
36 __be32 *p;
37 int ret;
38
39 p = (__be32 *)src->iov_base;
40 len = src->iov_len;
41 xid = *rdma_resp;
42
43 #ifdef SVCRDMA_BACKCHANNEL_DEBUG
44 pr_info("%s: xid=%08x, length=%zu\n",
45 __func__, be32_to_cpu(xid), len);
46 pr_info("%s: RPC/RDMA: %*ph\n",
47 __func__, (int)RPCRDMA_HDRLEN_MIN, rdma_resp);
48 pr_info("%s: RPC: %*ph\n",
49 __func__, (int)len, p);
50 #endif
51
52 ret = -EAGAIN;
53 if (src->iov_len < 24)
54 goto out_shortreply;
55
56 spin_lock(&xprt->recv_lock);
57 req = xprt_lookup_rqst(xprt, xid);
58 if (!req)
59 goto out_notfound;
60
61 dst = &req->rq_private_buf.head[0];
62 memcpy(&req->rq_private_buf, &req->rq_rcv_buf, sizeof(struct xdr_buf));
63 if (dst->iov_len < len)
64 goto out_unlock;
65 memcpy(dst->iov_base, p, len);
66
67 credits = be32_to_cpup(rdma_resp + 2);
68 if (credits == 0)
69 credits = 1; /* don't deadlock */
70 else if (credits > r_xprt->rx_buf.rb_bc_max_requests)
71 credits = r_xprt->rx_buf.rb_bc_max_requests;
72
73 spin_lock_bh(&xprt->transport_lock);
74 cwnd = xprt->cwnd;
75 xprt->cwnd = credits << RPC_CWNDSHIFT;
76 if (xprt->cwnd > cwnd)
77 xprt_release_rqst_cong(req->rq_task);
78 spin_unlock_bh(&xprt->transport_lock);
79
80
81 ret = 0;
82 xprt_complete_rqst(req->rq_task, rcvbuf->len);
83 rcvbuf->len = 0;
84
85 out_unlock:
86 spin_unlock(&xprt->recv_lock);
87 out:
88 return ret;
89
90 out_shortreply:
91 dprintk("svcrdma: short bc reply: xprt=%p, len=%zu\n",
92 xprt, src->iov_len);
93 goto out;
94
95 out_notfound:
96 dprintk("svcrdma: unrecognized bc reply: xprt=%p, xid=%08x\n",
97 xprt, be32_to_cpu(xid));
98
99 goto out_unlock;
100 }
101
102 /* Send a backwards direction RPC call.
103 *
104 * Caller holds the connection's mutex and has already marshaled
105 * the RPC/RDMA request.
106 *
107 * This is similar to svc_rdma_send_reply_msg, but takes a struct
108 * rpc_rqst instead, does not support chunks, and avoids blocking
109 * memory allocation.
110 *
111 * XXX: There is still an opportunity to block in svc_rdma_send()
112 * if there are no SQ entries to post the Send. This may occur if
113 * the adapter has a small maximum SQ depth.
114 */
svc_rdma_bc_sendto(struct svcxprt_rdma * rdma,struct rpc_rqst * rqst)115 static int svc_rdma_bc_sendto(struct svcxprt_rdma *rdma,
116 struct rpc_rqst *rqst)
117 {
118 struct svc_rdma_op_ctxt *ctxt;
119 int ret;
120
121 ctxt = svc_rdma_get_context(rdma);
122
123 /* rpcrdma_bc_send_request builds the transport header and
124 * the backchannel RPC message in the same buffer. Thus only
125 * one SGE is needed to send both.
126 */
127 ret = svc_rdma_map_reply_hdr(rdma, ctxt, rqst->rq_buffer,
128 rqst->rq_snd_buf.len);
129 if (ret < 0)
130 goto out_err;
131
132 ret = svc_rdma_repost_recv(rdma, GFP_NOIO);
133 if (ret)
134 goto out_err;
135
136 /* Bump page refcnt so Send completion doesn't release
137 * the rq_buffer before all retransmits are complete.
138 */
139 get_page(virt_to_page(rqst->rq_buffer));
140 ret = svc_rdma_post_send_wr(rdma, ctxt, 1, 0);
141 if (ret)
142 goto out_unmap;
143
144 out_err:
145 dprintk("svcrdma: %s returns %d\n", __func__, ret);
146 return ret;
147
148 out_unmap:
149 svc_rdma_unmap_dma(ctxt);
150 svc_rdma_put_context(ctxt, 1);
151 ret = -EIO;
152 goto out_err;
153 }
154
155 /* Server-side transport endpoint wants a whole page for its send
156 * buffer. The client RPC code constructs the RPC header in this
157 * buffer before it invokes ->send_request.
158 */
159 static int
xprt_rdma_bc_allocate(struct rpc_task * task)160 xprt_rdma_bc_allocate(struct rpc_task *task)
161 {
162 struct rpc_rqst *rqst = task->tk_rqstp;
163 size_t size = rqst->rq_callsize;
164 struct page *page;
165
166 if (size > PAGE_SIZE) {
167 WARN_ONCE(1, "svcrdma: large bc buffer request (size %zu)\n",
168 size);
169 return -EINVAL;
170 }
171
172 page = alloc_page(RPCRDMA_DEF_GFP);
173 if (!page)
174 return -ENOMEM;
175 rqst->rq_buffer = page_address(page);
176
177 rqst->rq_rbuffer = kmalloc(rqst->rq_rcvsize, RPCRDMA_DEF_GFP);
178 if (!rqst->rq_rbuffer) {
179 put_page(page);
180 return -ENOMEM;
181 }
182 return 0;
183 }
184
185 static void
xprt_rdma_bc_free(struct rpc_task * task)186 xprt_rdma_bc_free(struct rpc_task *task)
187 {
188 struct rpc_rqst *rqst = task->tk_rqstp;
189
190 put_page(virt_to_page(rqst->rq_buffer));
191 kfree(rqst->rq_rbuffer);
192 }
193
194 static int
rpcrdma_bc_send_request(struct svcxprt_rdma * rdma,struct rpc_rqst * rqst)195 rpcrdma_bc_send_request(struct svcxprt_rdma *rdma, struct rpc_rqst *rqst)
196 {
197 struct rpc_xprt *xprt = rqst->rq_xprt;
198 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
199 __be32 *p;
200 int rc;
201
202 /* Space in the send buffer for an RPC/RDMA header is reserved
203 * via xprt->tsh_size.
204 */
205 p = rqst->rq_buffer;
206 *p++ = rqst->rq_xid;
207 *p++ = rpcrdma_version;
208 *p++ = cpu_to_be32(r_xprt->rx_buf.rb_bc_max_requests);
209 *p++ = rdma_msg;
210 *p++ = xdr_zero;
211 *p++ = xdr_zero;
212 *p = xdr_zero;
213
214 #ifdef SVCRDMA_BACKCHANNEL_DEBUG
215 pr_info("%s: %*ph\n", __func__, 64, rqst->rq_buffer);
216 #endif
217
218 rc = svc_rdma_bc_sendto(rdma, rqst);
219 if (rc)
220 goto drop_connection;
221 return rc;
222
223 drop_connection:
224 dprintk("svcrdma: failed to send bc call\n");
225 xprt_disconnect_done(xprt);
226 return -ENOTCONN;
227 }
228
229 /* Send an RPC call on the passive end of a transport
230 * connection.
231 */
232 static int
xprt_rdma_bc_send_request(struct rpc_task * task)233 xprt_rdma_bc_send_request(struct rpc_task *task)
234 {
235 struct rpc_rqst *rqst = task->tk_rqstp;
236 struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt;
237 struct svcxprt_rdma *rdma;
238 int ret;
239
240 dprintk("svcrdma: sending bc call with xid: %08x\n",
241 be32_to_cpu(rqst->rq_xid));
242
243 if (!mutex_trylock(&sxprt->xpt_mutex)) {
244 rpc_sleep_on(&sxprt->xpt_bc_pending, task, NULL);
245 if (!mutex_trylock(&sxprt->xpt_mutex))
246 return -EAGAIN;
247 rpc_wake_up_queued_task(&sxprt->xpt_bc_pending, task);
248 }
249
250 ret = -ENOTCONN;
251 rdma = container_of(sxprt, struct svcxprt_rdma, sc_xprt);
252 if (!test_bit(XPT_DEAD, &sxprt->xpt_flags))
253 ret = rpcrdma_bc_send_request(rdma, rqst);
254
255 mutex_unlock(&sxprt->xpt_mutex);
256
257 if (ret < 0)
258 return ret;
259 return 0;
260 }
261
262 static void
xprt_rdma_bc_close(struct rpc_xprt * xprt)263 xprt_rdma_bc_close(struct rpc_xprt *xprt)
264 {
265 dprintk("svcrdma: %s: xprt %p\n", __func__, xprt);
266 }
267
268 static void
xprt_rdma_bc_put(struct rpc_xprt * xprt)269 xprt_rdma_bc_put(struct rpc_xprt *xprt)
270 {
271 dprintk("svcrdma: %s: xprt %p\n", __func__, xprt);
272
273 xprt_free(xprt);
274 module_put(THIS_MODULE);
275 }
276
277 static const struct rpc_xprt_ops xprt_rdma_bc_procs = {
278 .reserve_xprt = xprt_reserve_xprt_cong,
279 .release_xprt = xprt_release_xprt_cong,
280 .alloc_slot = xprt_alloc_slot,
281 .release_request = xprt_release_rqst_cong,
282 .buf_alloc = xprt_rdma_bc_allocate,
283 .buf_free = xprt_rdma_bc_free,
284 .send_request = xprt_rdma_bc_send_request,
285 .set_retrans_timeout = xprt_set_retrans_timeout_def,
286 .close = xprt_rdma_bc_close,
287 .destroy = xprt_rdma_bc_put,
288 .print_stats = xprt_rdma_print_stats
289 };
290
291 static const struct rpc_timeout xprt_rdma_bc_timeout = {
292 .to_initval = 60 * HZ,
293 .to_maxval = 60 * HZ,
294 };
295
296 /* It shouldn't matter if the number of backchannel session slots
297 * doesn't match the number of RPC/RDMA credits. That just means
298 * one or the other will have extra slots that aren't used.
299 */
300 static struct rpc_xprt *
xprt_setup_rdma_bc(struct xprt_create * args)301 xprt_setup_rdma_bc(struct xprt_create *args)
302 {
303 struct rpc_xprt *xprt;
304 struct rpcrdma_xprt *new_xprt;
305
306 if (args->addrlen > sizeof(xprt->addr)) {
307 dprintk("RPC: %s: address too large\n", __func__);
308 return ERR_PTR(-EBADF);
309 }
310
311 xprt = xprt_alloc(args->net, sizeof(*new_xprt),
312 RPCRDMA_MAX_BC_REQUESTS,
313 RPCRDMA_MAX_BC_REQUESTS);
314 if (!xprt) {
315 dprintk("RPC: %s: couldn't allocate rpc_xprt\n",
316 __func__);
317 return ERR_PTR(-ENOMEM);
318 }
319
320 xprt->timeout = &xprt_rdma_bc_timeout;
321 xprt_set_bound(xprt);
322 xprt_set_connected(xprt);
323 xprt->bind_timeout = RPCRDMA_BIND_TO;
324 xprt->reestablish_timeout = RPCRDMA_INIT_REEST_TO;
325 xprt->idle_timeout = RPCRDMA_IDLE_DISC_TO;
326
327 xprt->prot = XPRT_TRANSPORT_BC_RDMA;
328 xprt->tsh_size = RPCRDMA_HDRLEN_MIN / sizeof(__be32);
329 xprt->ops = &xprt_rdma_bc_procs;
330
331 memcpy(&xprt->addr, args->dstaddr, args->addrlen);
332 xprt->addrlen = args->addrlen;
333 xprt_rdma_format_addresses(xprt, (struct sockaddr *)&xprt->addr);
334 xprt->resvport = 0;
335
336 xprt->max_payload = xprt_rdma_max_inline_read;
337
338 new_xprt = rpcx_to_rdmax(xprt);
339 new_xprt->rx_buf.rb_bc_max_requests = xprt->max_reqs;
340
341 xprt_get(xprt);
342 args->bc_xprt->xpt_bc_xprt = xprt;
343 xprt->bc_xprt = args->bc_xprt;
344
345 if (!try_module_get(THIS_MODULE))
346 goto out_fail;
347
348 /* Final put for backchannel xprt is in __svc_rdma_free */
349 xprt_get(xprt);
350 return xprt;
351
352 out_fail:
353 xprt_rdma_free_addresses(xprt);
354 args->bc_xprt->xpt_bc_xprt = NULL;
355 args->bc_xprt->xpt_bc_xps = NULL;
356 xprt_put(xprt);
357 xprt_free(xprt);
358 return ERR_PTR(-EINVAL);
359 }
360
361 struct xprt_class xprt_rdma_bc = {
362 .list = LIST_HEAD_INIT(xprt_rdma_bc.list),
363 .name = "rdma backchannel",
364 .owner = THIS_MODULE,
365 .ident = XPRT_TRANSPORT_BC_RDMA,
366 .setup = xprt_setup_rdma_bc,
367 };
368