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/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 backwards 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_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 return svc_rdma_send(rdma, sctxt);
97 }
98
99 /* Server-side transport endpoint wants a whole page for its send
100 * buffer. The client RPC code constructs the RPC header in this
101 * buffer before it invokes ->send_request.
102 */
103 static int
104 xprt_rdma_bc_allocate(struct rpc_task *task)
105 {
106 struct rpc_rqst *rqst = task->tk_rqstp;
107 size_t size = rqst->rq_callsize;
108 struct page *page;
109
110 if (size > PAGE_SIZE) {
111 WARN_ONCE(1, "svcrdma: large bc buffer request (size %zu)\n",
112 size);
113 return -EINVAL;
114 }
115
116 page = alloc_page(RPCRDMA_DEF_GFP);
117 if (!page)
118 return -ENOMEM;
119 rqst->rq_buffer = page_address(page);
120
121 rqst->rq_rbuffer = kmalloc(rqst->rq_rcvsize, RPCRDMA_DEF_GFP);
122 if (!rqst->rq_rbuffer) {
123 put_page(page);
124 return -ENOMEM;
125 }
126 return 0;
127 }
128
129 static void
130 xprt_rdma_bc_free(struct rpc_task *task)
131 {
132 struct rpc_rqst *rqst = task->tk_rqstp;
133
134 put_page(virt_to_page(rqst->rq_buffer));
135 kfree(rqst->rq_rbuffer);
136 }
137
138 static int
139 rpcrdma_bc_send_request(struct svcxprt_rdma *rdma, struct rpc_rqst *rqst)
140 {
141 struct rpc_xprt *xprt = rqst->rq_xprt;
142 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
143 struct svc_rdma_send_ctxt *ctxt;
144 __be32 *p;
145 int rc;
146
147 ctxt = svc_rdma_send_ctxt_get(rdma);
148 if (!ctxt)
149 goto drop_connection;
150
151 p = xdr_reserve_space(&ctxt->sc_stream, RPCRDMA_HDRLEN_MIN);
152 if (!p)
153 goto put_ctxt;
154 *p++ = rqst->rq_xid;
155 *p++ = rpcrdma_version;
156 *p++ = cpu_to_be32(r_xprt->rx_buf.rb_bc_max_requests);
157 *p++ = rdma_msg;
158 *p++ = xdr_zero;
159 *p++ = xdr_zero;
160 *p = xdr_zero;
161
162 rqst->rq_xtime = ktime_get();
163 rc = svc_rdma_bc_sendto(rdma, rqst, ctxt);
164 if (rc)
165 goto put_ctxt;
166 return 0;
167
168 put_ctxt:
169 svc_rdma_send_ctxt_put(rdma, ctxt);
170
171 drop_connection:
172 return -ENOTCONN;
173 }
174
175 /**
176 * xprt_rdma_bc_send_request - Send a reverse-direction Call
177 * @rqst: rpc_rqst containing Call message to be sent
178 *
179 * Return values:
180 * %0 if the message was sent successfully
181 * %ENOTCONN if the message was not sent
182 */
183 static int xprt_rdma_bc_send_request(struct rpc_rqst *rqst)
184 {
185 struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt;
186 struct svcxprt_rdma *rdma =
187 container_of(sxprt, struct svcxprt_rdma, sc_xprt);
188 int ret;
189
190 if (test_bit(XPT_DEAD, &sxprt->xpt_flags))
191 return -ENOTCONN;
192
193 ret = rpcrdma_bc_send_request(rdma, rqst);
194 if (ret == -ENOTCONN)
195 svc_close_xprt(sxprt);
196 return ret;
197 }
198
199 static void
200 xprt_rdma_bc_close(struct rpc_xprt *xprt)
201 {
202 xprt_disconnect_done(xprt);
203 xprt->cwnd = RPC_CWNDSHIFT;
204 }
205
206 static void
207 xprt_rdma_bc_put(struct rpc_xprt *xprt)
208 {
209 xprt_rdma_free_addresses(xprt);
210 xprt_free(xprt);
211 }
212
213 static const struct rpc_xprt_ops xprt_rdma_bc_procs = {
214 .reserve_xprt = xprt_reserve_xprt_cong,
215 .release_xprt = xprt_release_xprt_cong,
216 .alloc_slot = xprt_alloc_slot,
217 .free_slot = xprt_free_slot,
218 .release_request = xprt_release_rqst_cong,
219 .buf_alloc = xprt_rdma_bc_allocate,
220 .buf_free = xprt_rdma_bc_free,
221 .send_request = xprt_rdma_bc_send_request,
222 .wait_for_reply_request = xprt_wait_for_reply_request_def,
223 .close = xprt_rdma_bc_close,
224 .destroy = xprt_rdma_bc_put,
225 .print_stats = xprt_rdma_print_stats
226 };
227
228 static const struct rpc_timeout xprt_rdma_bc_timeout = {
229 .to_initval = 60 * HZ,
230 .to_maxval = 60 * HZ,
231 };
232
233 /* It shouldn't matter if the number of backchannel session slots
234 * doesn't match the number of RPC/RDMA credits. That just means
235 * one or the other will have extra slots that aren't used.
236 */
237 static struct rpc_xprt *
238 xprt_setup_rdma_bc(struct xprt_create *args)
239 {
240 struct rpc_xprt *xprt;
241 struct rpcrdma_xprt *new_xprt;
242
243 if (args->addrlen > sizeof(xprt->addr))
244 return ERR_PTR(-EBADF);
245
246 xprt = xprt_alloc(args->net, sizeof(*new_xprt),
247 RPCRDMA_MAX_BC_REQUESTS,
248 RPCRDMA_MAX_BC_REQUESTS);
249 if (!xprt)
250 return ERR_PTR(-ENOMEM);
251
252 xprt->timeout = &xprt_rdma_bc_timeout;
253 xprt_set_bound(xprt);
254 xprt_set_connected(xprt);
255 xprt->bind_timeout = 0;
256 xprt->reestablish_timeout = 0;
257 xprt->idle_timeout = 0;
258
259 xprt->prot = XPRT_TRANSPORT_BC_RDMA;
260 xprt->ops = &xprt_rdma_bc_procs;
261
262 memcpy(&xprt->addr, args->dstaddr, args->addrlen);
263 xprt->addrlen = args->addrlen;
264 xprt_rdma_format_addresses(xprt, (struct sockaddr *)&xprt->addr);
265 xprt->resvport = 0;
266
267 xprt->max_payload = xprt_rdma_max_inline_read;
268
269 new_xprt = rpcx_to_rdmax(xprt);
270 new_xprt->rx_buf.rb_bc_max_requests = xprt->max_reqs;
271
272 xprt_get(xprt);
273 args->bc_xprt->xpt_bc_xprt = xprt;
274 xprt->bc_xprt = args->bc_xprt;
275
276 /* Final put for backchannel xprt is in __svc_rdma_free */
277 xprt_get(xprt);
278 return xprt;
279 }
280
281 struct xprt_class xprt_rdma_bc = {
282 .list = LIST_HEAD_INIT(xprt_rdma_bc.list),
283 .name = "rdma backchannel",
284 .owner = THIS_MODULE,
285 .ident = XPRT_TRANSPORT_BC_RDMA,
286 .setup = xprt_setup_rdma_bc,
287 };
288
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