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 */
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 */
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_pcl empty_pcl;
80 int ret;
81
82 pcl_init(&empty_pcl);
83 ret = svc_rdma_map_reply_msg(rdma, sctxt, &empty_pcl, &empty_pcl,
84 &rqst->rq_snd_buf);
85 if (ret < 0)
86 return -EIO;
87
88 /* Bump page refcnt so Send completion doesn't release
89 * the rq_buffer before all retransmits are complete.
90 */
91 get_page(virt_to_page(rqst->rq_buffer));
92 sctxt->sc_send_wr.opcode = IB_WR_SEND;
93 return svc_rdma_post_send(rdma, sctxt);
94 }
95
96 /* Server-side transport endpoint wants a whole page for its send
97 * buffer. The client RPC code constructs the RPC header in this
98 * buffer before it invokes ->send_request.
99 */
100 static int
101 xprt_rdma_bc_allocate(struct rpc_task *task)
102 {
103 struct rpc_rqst *rqst = task->tk_rqstp;
104 size_t size = rqst->rq_callsize;
105 struct page *page;
106
107 if (size > PAGE_SIZE) {
108 WARN_ONCE(1, "svcrdma: large bc buffer request (size %zu)\n",
109 size);
110 return -EINVAL;
111 }
112
113 page = alloc_page(GFP_NOIO | __GFP_NOWARN);
114 if (!page)
115 return -ENOMEM;
116 rqst->rq_buffer = page_address(page);
117
118 rqst->rq_rbuffer = kmalloc(rqst->rq_rcvsize, GFP_NOIO | __GFP_NOWARN);
119 if (!rqst->rq_rbuffer) {
120 put_page(page);
121 return -ENOMEM;
122 }
123 return 0;
124 }
125
126 static void
127 xprt_rdma_bc_free(struct rpc_task *task)
128 {
129 struct rpc_rqst *rqst = task->tk_rqstp;
130
131 put_page(virt_to_page(rqst->rq_buffer));
132 kfree(rqst->rq_rbuffer);
133 }
134
135 static int
136 rpcrdma_bc_send_request(struct svcxprt_rdma *rdma, struct rpc_rqst *rqst)
137 {
138 struct rpc_xprt *xprt = rqst->rq_xprt;
139 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
140 struct svc_rdma_send_ctxt *ctxt;
141 __be32 *p;
142 int rc;
143
144 ctxt = svc_rdma_send_ctxt_get(rdma);
145 if (!ctxt)
146 goto drop_connection;
147
148 p = xdr_reserve_space(&ctxt->sc_stream, RPCRDMA_HDRLEN_MIN);
149 if (!p)
150 goto put_ctxt;
151 *p++ = rqst->rq_xid;
152 *p++ = rpcrdma_version;
153 *p++ = cpu_to_be32(r_xprt->rx_buf.rb_bc_max_requests);
154 *p++ = rdma_msg;
155 *p++ = xdr_zero;
156 *p++ = xdr_zero;
157 *p = xdr_zero;
158
159 rqst->rq_xtime = ktime_get();
160 rc = svc_rdma_bc_sendto(rdma, rqst, ctxt);
161 if (rc)
162 goto put_ctxt;
163 return 0;
164
165 put_ctxt:
166 svc_rdma_send_ctxt_put(rdma, ctxt);
167
168 drop_connection:
169 return -ENOTCONN;
170 }
171
172 /**
173 * xprt_rdma_bc_send_request - Send a reverse-direction Call
174 * @rqst: rpc_rqst containing Call message to be sent
175 *
176 * Return values:
177 * %0 if the message was sent successfully
178 * %ENOTCONN if the message was not sent
179 */
180 static int xprt_rdma_bc_send_request(struct rpc_rqst *rqst)
181 {
182 struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt;
183 struct svcxprt_rdma *rdma =
184 container_of(sxprt, struct svcxprt_rdma, sc_xprt);
185 int ret;
186
187 if (test_bit(XPT_DEAD, &sxprt->xpt_flags))
188 return -ENOTCONN;
189
190 ret = rpcrdma_bc_send_request(rdma, rqst);
191 if (ret == -ENOTCONN)
192 svc_xprt_close(sxprt);
193 return ret;
194 }
195
196 static void
197 xprt_rdma_bc_close(struct rpc_xprt *xprt)
198 {
199 xprt_disconnect_done(xprt);
200 xprt->cwnd = RPC_CWNDSHIFT;
201 }
202
203 static void
204 xprt_rdma_bc_put(struct rpc_xprt *xprt)
205 {
206 xprt_rdma_free_addresses(xprt);
207 xprt_free(xprt);
208 }
209
210 static const struct rpc_xprt_ops xprt_rdma_bc_procs = {
211 .reserve_xprt = xprt_reserve_xprt_cong,
212 .release_xprt = xprt_release_xprt_cong,
213 .alloc_slot = xprt_alloc_slot,
214 .free_slot = xprt_free_slot,
215 .release_request = xprt_release_rqst_cong,
216 .buf_alloc = xprt_rdma_bc_allocate,
217 .buf_free = xprt_rdma_bc_free,
218 .send_request = xprt_rdma_bc_send_request,
219 .wait_for_reply_request = xprt_wait_for_reply_request_def,
220 .close = xprt_rdma_bc_close,
221 .destroy = xprt_rdma_bc_put,
222 .print_stats = xprt_rdma_print_stats
223 };
224
225 static const struct rpc_timeout xprt_rdma_bc_timeout = {
226 .to_initval = 60 * HZ,
227 .to_maxval = 60 * HZ,
228 };
229
230 /* It shouldn't matter if the number of backchannel session slots
231 * doesn't match the number of RPC/RDMA credits. That just means
232 * one or the other will have extra slots that aren't used.
233 */
234 static struct rpc_xprt *
235 xprt_setup_rdma_bc(struct xprt_create *args)
236 {
237 struct rpc_xprt *xprt;
238 struct rpcrdma_xprt *new_xprt;
239
240 if (args->addrlen > sizeof(xprt->addr))
241 return ERR_PTR(-EBADF);
242
243 xprt = xprt_alloc(args->net, sizeof(*new_xprt),
244 RPCRDMA_MAX_BC_REQUESTS,
245 RPCRDMA_MAX_BC_REQUESTS);
246 if (!xprt)
247 return ERR_PTR(-ENOMEM);
248
249 xprt->timeout = &xprt_rdma_bc_timeout;
250 xprt_set_bound(xprt);
251 xprt_set_connected(xprt);
252 xprt->bind_timeout = 0;
253 xprt->reestablish_timeout = 0;
254 xprt->idle_timeout = 0;
255
256 xprt->prot = XPRT_TRANSPORT_BC_RDMA;
257 xprt->ops = &xprt_rdma_bc_procs;
258
259 memcpy(&xprt->addr, args->dstaddr, args->addrlen);
260 xprt->addrlen = args->addrlen;
261 xprt_rdma_format_addresses(xprt, (struct sockaddr *)&xprt->addr);
262 xprt->resvport = 0;
263
264 xprt->max_payload = xprt_rdma_max_inline_read;
265
266 new_xprt = rpcx_to_rdmax(xprt);
267 new_xprt->rx_buf.rb_bc_max_requests = xprt->max_reqs;
268
269 xprt_get(xprt);
270 args->bc_xprt->xpt_bc_xprt = xprt;
271 xprt->bc_xprt = args->bc_xprt;
272
273 /* Final put for backchannel xprt is in __svc_rdma_free */
274 xprt_get(xprt);
275 return xprt;
276 }
277
278 struct xprt_class xprt_rdma_bc = {
279 .list = LIST_HEAD_INIT(xprt_rdma_bc.list),
280 .name = "rdma backchannel",
281 .owner = THIS_MODULE,
282 .ident = XPRT_TRANSPORT_BC_RDMA,
283 .setup = xprt_setup_rdma_bc,
284 };
285
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