1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (c) 2015-2018 Oracle. All rights reserved.
4 *
5 * Support for reverse-direction RPCs on RPC/RDMA (server-side).
6 */
7
8 #include <linux/sunrpc/svc_rdma.h>
9
10 #include "xprt_rdma.h"
11 #include <trace/events/rpcrdma.h>
12
13 /**
14 * svc_rdma_handle_bc_reply - Process incoming backchannel Reply
15 * @rqstp: resources for handling the Reply
16 * @rctxt: Received message
17 *
18 */
svc_rdma_handle_bc_reply(struct svc_rqst * rqstp,struct svc_rdma_recv_ctxt * rctxt)19 void svc_rdma_handle_bc_reply(struct svc_rqst *rqstp,
20 struct svc_rdma_recv_ctxt *rctxt)
21 {
22 struct svc_xprt *sxprt = rqstp->rq_xprt;
23 struct rpc_xprt *xprt = sxprt->xpt_bc_xprt;
24 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
25 struct xdr_buf *rcvbuf = &rqstp->rq_arg;
26 struct kvec *dst, *src = &rcvbuf->head[0];
27 __be32 *rdma_resp = rctxt->rc_recv_buf;
28 struct rpc_rqst *req;
29 u32 credits;
30
31 spin_lock(&xprt->queue_lock);
32 req = xprt_lookup_rqst(xprt, *rdma_resp);
33 if (!req)
34 goto out_unlock;
35
36 dst = &req->rq_private_buf.head[0];
37 memcpy(&req->rq_private_buf, &req->rq_rcv_buf, sizeof(struct xdr_buf));
38 if (dst->iov_len < src->iov_len)
39 goto out_unlock;
40 memcpy(dst->iov_base, src->iov_base, src->iov_len);
41 xprt_pin_rqst(req);
42 spin_unlock(&xprt->queue_lock);
43
44 credits = be32_to_cpup(rdma_resp + 2);
45 if (credits == 0)
46 credits = 1; /* don't deadlock */
47 else if (credits > r_xprt->rx_buf.rb_bc_max_requests)
48 credits = r_xprt->rx_buf.rb_bc_max_requests;
49 spin_lock(&xprt->transport_lock);
50 xprt->cwnd = credits << RPC_CWNDSHIFT;
51 spin_unlock(&xprt->transport_lock);
52
53 spin_lock(&xprt->queue_lock);
54 xprt_complete_rqst(req->rq_task, rcvbuf->len);
55 xprt_unpin_rqst(req);
56 rcvbuf->len = 0;
57
58 out_unlock:
59 spin_unlock(&xprt->queue_lock);
60 }
61
62 /* Send a reverse-direction RPC Call.
63 *
64 * Caller holds the connection's mutex and has already marshaled
65 * the RPC/RDMA request.
66 *
67 * This is similar to svc_rdma_send_reply_msg, but takes a struct
68 * rpc_rqst instead, does not support chunks, and avoids blocking
69 * memory allocation.
70 *
71 * XXX: There is still an opportunity to block in svc_rdma_send()
72 * if there are no SQ entries to post the Send. This may occur if
73 * the adapter has a small maximum SQ depth.
74 */
svc_rdma_bc_sendto(struct svcxprt_rdma * rdma,struct rpc_rqst * rqst,struct svc_rdma_send_ctxt * sctxt)75 static int svc_rdma_bc_sendto(struct svcxprt_rdma *rdma,
76 struct rpc_rqst *rqst,
77 struct svc_rdma_send_ctxt *sctxt)
78 {
79 struct svc_rdma_recv_ctxt *rctxt;
80 int ret;
81
82 rctxt = svc_rdma_recv_ctxt_get(rdma);
83 if (!rctxt)
84 return -EIO;
85
86 ret = svc_rdma_map_reply_msg(rdma, sctxt, rctxt, &rqst->rq_snd_buf);
87 svc_rdma_recv_ctxt_put(rdma, rctxt);
88 if (ret < 0)
89 return -EIO;
90
91 /* Bump page refcnt so Send completion doesn't release
92 * the rq_buffer before all retransmits are complete.
93 */
94 get_page(virt_to_page(rqst->rq_buffer));
95 sctxt->sc_send_wr.opcode = IB_WR_SEND;
96 ret = svc_rdma_send(rdma, sctxt);
97 if (ret < 0)
98 return ret;
99
100 ret = wait_for_completion_killable(&sctxt->sc_done);
101 svc_rdma_send_ctxt_put(rdma, sctxt);
102 return ret;
103 }
104
105 /* Server-side transport endpoint wants a whole page for its send
106 * buffer. The client RPC code constructs the RPC header in this
107 * buffer before it invokes ->send_request.
108 */
109 static int
xprt_rdma_bc_allocate(struct rpc_task * task)110 xprt_rdma_bc_allocate(struct rpc_task *task)
111 {
112 struct rpc_rqst *rqst = task->tk_rqstp;
113 size_t size = rqst->rq_callsize;
114 struct page *page;
115
116 if (size > PAGE_SIZE) {
117 WARN_ONCE(1, "svcrdma: large bc buffer request (size %zu)\n",
118 size);
119 return -EINVAL;
120 }
121
122 page = alloc_page(RPCRDMA_DEF_GFP);
123 if (!page)
124 return -ENOMEM;
125 rqst->rq_buffer = page_address(page);
126
127 rqst->rq_rbuffer = kmalloc(rqst->rq_rcvsize, RPCRDMA_DEF_GFP);
128 if (!rqst->rq_rbuffer) {
129 put_page(page);
130 return -ENOMEM;
131 }
132 return 0;
133 }
134
135 static void
xprt_rdma_bc_free(struct rpc_task * task)136 xprt_rdma_bc_free(struct rpc_task *task)
137 {
138 struct rpc_rqst *rqst = task->tk_rqstp;
139
140 put_page(virt_to_page(rqst->rq_buffer));
141 kfree(rqst->rq_rbuffer);
142 }
143
144 static int
rpcrdma_bc_send_request(struct svcxprt_rdma * rdma,struct rpc_rqst * rqst)145 rpcrdma_bc_send_request(struct svcxprt_rdma *rdma, struct rpc_rqst *rqst)
146 {
147 struct rpc_xprt *xprt = rqst->rq_xprt;
148 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
149 struct svc_rdma_send_ctxt *ctxt;
150 __be32 *p;
151 int rc;
152
153 ctxt = svc_rdma_send_ctxt_get(rdma);
154 if (!ctxt)
155 goto drop_connection;
156
157 p = xdr_reserve_space(&ctxt->sc_stream, RPCRDMA_HDRLEN_MIN);
158 if (!p)
159 goto put_ctxt;
160 *p++ = rqst->rq_xid;
161 *p++ = rpcrdma_version;
162 *p++ = cpu_to_be32(r_xprt->rx_buf.rb_bc_max_requests);
163 *p++ = rdma_msg;
164 *p++ = xdr_zero;
165 *p++ = xdr_zero;
166 *p = xdr_zero;
167
168 rqst->rq_xtime = ktime_get();
169 rc = svc_rdma_bc_sendto(rdma, rqst, ctxt);
170 if (rc)
171 goto put_ctxt;
172 return 0;
173
174 put_ctxt:
175 svc_rdma_send_ctxt_put(rdma, ctxt);
176
177 drop_connection:
178 return -ENOTCONN;
179 }
180
181 /**
182 * xprt_rdma_bc_send_request - Send a reverse-direction Call
183 * @rqst: rpc_rqst containing Call message to be sent
184 *
185 * Return values:
186 * %0 if the message was sent successfully
187 * %ENOTCONN if the message was not sent
188 */
xprt_rdma_bc_send_request(struct rpc_rqst * rqst)189 static int xprt_rdma_bc_send_request(struct rpc_rqst *rqst)
190 {
191 struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt;
192 struct svcxprt_rdma *rdma =
193 container_of(sxprt, struct svcxprt_rdma, sc_xprt);
194 int ret;
195
196 if (test_bit(XPT_DEAD, &sxprt->xpt_flags))
197 return -ENOTCONN;
198
199 ret = rpcrdma_bc_send_request(rdma, rqst);
200 if (ret == -ENOTCONN)
201 svc_close_xprt(sxprt);
202 return ret;
203 }
204
205 static void
xprt_rdma_bc_close(struct rpc_xprt * xprt)206 xprt_rdma_bc_close(struct rpc_xprt *xprt)
207 {
208 xprt_disconnect_done(xprt);
209 xprt->cwnd = RPC_CWNDSHIFT;
210 }
211
212 static void
xprt_rdma_bc_put(struct rpc_xprt * xprt)213 xprt_rdma_bc_put(struct rpc_xprt *xprt)
214 {
215 xprt_rdma_free_addresses(xprt);
216 xprt_free(xprt);
217 }
218
219 static const struct rpc_xprt_ops xprt_rdma_bc_procs = {
220 .reserve_xprt = xprt_reserve_xprt_cong,
221 .release_xprt = xprt_release_xprt_cong,
222 .alloc_slot = xprt_alloc_slot,
223 .free_slot = xprt_free_slot,
224 .release_request = xprt_release_rqst_cong,
225 .buf_alloc = xprt_rdma_bc_allocate,
226 .buf_free = xprt_rdma_bc_free,
227 .send_request = xprt_rdma_bc_send_request,
228 .wait_for_reply_request = xprt_wait_for_reply_request_def,
229 .close = xprt_rdma_bc_close,
230 .destroy = xprt_rdma_bc_put,
231 .print_stats = xprt_rdma_print_stats
232 };
233
234 static const struct rpc_timeout xprt_rdma_bc_timeout = {
235 .to_initval = 60 * HZ,
236 .to_maxval = 60 * HZ,
237 };
238
239 /* It shouldn't matter if the number of backchannel session slots
240 * doesn't match the number of RPC/RDMA credits. That just means
241 * one or the other will have extra slots that aren't used.
242 */
243 static struct rpc_xprt *
xprt_setup_rdma_bc(struct xprt_create * args)244 xprt_setup_rdma_bc(struct xprt_create *args)
245 {
246 struct rpc_xprt *xprt;
247 struct rpcrdma_xprt *new_xprt;
248
249 if (args->addrlen > sizeof(xprt->addr))
250 return ERR_PTR(-EBADF);
251
252 xprt = xprt_alloc(args->net, sizeof(*new_xprt),
253 RPCRDMA_MAX_BC_REQUESTS,
254 RPCRDMA_MAX_BC_REQUESTS);
255 if (!xprt)
256 return ERR_PTR(-ENOMEM);
257
258 xprt->timeout = &xprt_rdma_bc_timeout;
259 xprt_set_bound(xprt);
260 xprt_set_connected(xprt);
261 xprt->bind_timeout = 0;
262 xprt->reestablish_timeout = 0;
263 xprt->idle_timeout = 0;
264
265 xprt->prot = XPRT_TRANSPORT_BC_RDMA;
266 xprt->ops = &xprt_rdma_bc_procs;
267
268 memcpy(&xprt->addr, args->dstaddr, args->addrlen);
269 xprt->addrlen = args->addrlen;
270 xprt_rdma_format_addresses(xprt, (struct sockaddr *)&xprt->addr);
271 xprt->resvport = 0;
272
273 xprt->max_payload = xprt_rdma_max_inline_read;
274
275 new_xprt = rpcx_to_rdmax(xprt);
276 new_xprt->rx_buf.rb_bc_max_requests = xprt->max_reqs;
277
278 xprt_get(xprt);
279 args->bc_xprt->xpt_bc_xprt = xprt;
280 xprt->bc_xprt = args->bc_xprt;
281
282 /* Final put for backchannel xprt is in __svc_rdma_free */
283 xprt_get(xprt);
284 return xprt;
285 }
286
287 struct xprt_class xprt_rdma_bc = {
288 .list = LIST_HEAD_INIT(xprt_rdma_bc.list),
289 .name = "rdma backchannel",
290 .owner = THIS_MODULE,
291 .ident = XPRT_TRANSPORT_BC_RDMA,
292 .setup = xprt_setup_rdma_bc,
293 };
294