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 */
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 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 */
svc_rdma_bc_sendto(struct svcxprt_rdma * rdma,struct rpc_rqst * rqst,struct svc_rdma_send_ctxt * ctxt)75 static int svc_rdma_bc_sendto(struct svcxprt_rdma *rdma,
76 struct rpc_rqst *rqst,
77 struct svc_rdma_send_ctxt *ctxt)
78 {
79 int ret;
80
81 ret = svc_rdma_map_reply_msg(rdma, ctxt, NULL, &rqst->rq_snd_buf);
82 if (ret < 0)
83 return -EIO;
84
85 /* Bump page refcnt so Send completion doesn't release
86 * the rq_buffer before all retransmits are complete.
87 */
88 get_page(virt_to_page(rqst->rq_buffer));
89 ctxt->sc_send_wr.opcode = IB_WR_SEND;
90 return svc_rdma_send(rdma, ctxt);
91 }
92
93 /* Server-side transport endpoint wants a whole page for its send
94 * buffer. The client RPC code constructs the RPC header in this
95 * buffer before it invokes ->send_request.
96 */
97 static int
xprt_rdma_bc_allocate(struct rpc_task * task)98 xprt_rdma_bc_allocate(struct rpc_task *task)
99 {
100 struct rpc_rqst *rqst = task->tk_rqstp;
101 size_t size = rqst->rq_callsize;
102 struct page *page;
103
104 if (size > PAGE_SIZE) {
105 WARN_ONCE(1, "svcrdma: large bc buffer request (size %zu)\n",
106 size);
107 return -EINVAL;
108 }
109
110 page = alloc_page(RPCRDMA_DEF_GFP);
111 if (!page)
112 return -ENOMEM;
113 rqst->rq_buffer = page_address(page);
114
115 rqst->rq_rbuffer = kmalloc(rqst->rq_rcvsize, RPCRDMA_DEF_GFP);
116 if (!rqst->rq_rbuffer) {
117 put_page(page);
118 return -ENOMEM;
119 }
120 return 0;
121 }
122
123 static void
xprt_rdma_bc_free(struct rpc_task * task)124 xprt_rdma_bc_free(struct rpc_task *task)
125 {
126 struct rpc_rqst *rqst = task->tk_rqstp;
127
128 put_page(virt_to_page(rqst->rq_buffer));
129 kfree(rqst->rq_rbuffer);
130 }
131
132 static int
rpcrdma_bc_send_request(struct svcxprt_rdma * rdma,struct rpc_rqst * rqst)133 rpcrdma_bc_send_request(struct svcxprt_rdma *rdma, struct rpc_rqst *rqst)
134 {
135 struct rpc_xprt *xprt = rqst->rq_xprt;
136 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
137 struct svc_rdma_send_ctxt *ctxt;
138 __be32 *p;
139 int rc;
140
141 ctxt = svc_rdma_send_ctxt_get(rdma);
142 if (!ctxt)
143 goto drop_connection;
144
145 p = xdr_reserve_space(&ctxt->sc_stream, RPCRDMA_HDRLEN_MIN);
146 if (!p)
147 goto put_ctxt;
148 *p++ = rqst->rq_xid;
149 *p++ = rpcrdma_version;
150 *p++ = cpu_to_be32(r_xprt->rx_buf.rb_bc_max_requests);
151 *p++ = rdma_msg;
152 *p++ = xdr_zero;
153 *p++ = xdr_zero;
154 *p = xdr_zero;
155
156 rqst->rq_xtime = ktime_get();
157 rc = svc_rdma_bc_sendto(rdma, rqst, ctxt);
158 if (rc)
159 goto put_ctxt;
160 return 0;
161
162 put_ctxt:
163 svc_rdma_send_ctxt_put(rdma, ctxt);
164
165 drop_connection:
166 return -ENOTCONN;
167 }
168
169 /**
170 * xprt_rdma_bc_send_request - Send a reverse-direction Call
171 * @rqst: rpc_rqst containing Call message to be sent
172 *
173 * Return values:
174 * %0 if the message was sent successfully
175 * %ENOTCONN if the message was not sent
176 */
xprt_rdma_bc_send_request(struct rpc_rqst * rqst)177 static int xprt_rdma_bc_send_request(struct rpc_rqst *rqst)
178 {
179 struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt;
180 struct svcxprt_rdma *rdma =
181 container_of(sxprt, struct svcxprt_rdma, sc_xprt);
182 int ret;
183
184 if (test_bit(XPT_DEAD, &sxprt->xpt_flags))
185 return -ENOTCONN;
186
187 ret = rpcrdma_bc_send_request(rdma, rqst);
188 if (ret == -ENOTCONN)
189 svc_close_xprt(sxprt);
190 return ret;
191 }
192
193 static void
xprt_rdma_bc_close(struct rpc_xprt * xprt)194 xprt_rdma_bc_close(struct rpc_xprt *xprt)
195 {
196 xprt_disconnect_done(xprt);
197 xprt->cwnd = RPC_CWNDSHIFT;
198 }
199
200 static void
xprt_rdma_bc_put(struct rpc_xprt * xprt)201 xprt_rdma_bc_put(struct rpc_xprt *xprt)
202 {
203 xprt_rdma_free_addresses(xprt);
204 xprt_free(xprt);
205 }
206
207 static const struct rpc_xprt_ops xprt_rdma_bc_procs = {
208 .reserve_xprt = xprt_reserve_xprt_cong,
209 .release_xprt = xprt_release_xprt_cong,
210 .alloc_slot = xprt_alloc_slot,
211 .free_slot = xprt_free_slot,
212 .release_request = xprt_release_rqst_cong,
213 .buf_alloc = xprt_rdma_bc_allocate,
214 .buf_free = xprt_rdma_bc_free,
215 .send_request = xprt_rdma_bc_send_request,
216 .wait_for_reply_request = xprt_wait_for_reply_request_def,
217 .close = xprt_rdma_bc_close,
218 .destroy = xprt_rdma_bc_put,
219 .print_stats = xprt_rdma_print_stats
220 };
221
222 static const struct rpc_timeout xprt_rdma_bc_timeout = {
223 .to_initval = 60 * HZ,
224 .to_maxval = 60 * HZ,
225 };
226
227 /* It shouldn't matter if the number of backchannel session slots
228 * doesn't match the number of RPC/RDMA credits. That just means
229 * one or the other will have extra slots that aren't used.
230 */
231 static struct rpc_xprt *
xprt_setup_rdma_bc(struct xprt_create * args)232 xprt_setup_rdma_bc(struct xprt_create *args)
233 {
234 struct rpc_xprt *xprt;
235 struct rpcrdma_xprt *new_xprt;
236
237 if (args->addrlen > sizeof(xprt->addr))
238 return ERR_PTR(-EBADF);
239
240 xprt = xprt_alloc(args->net, sizeof(*new_xprt),
241 RPCRDMA_MAX_BC_REQUESTS,
242 RPCRDMA_MAX_BC_REQUESTS);
243 if (!xprt)
244 return ERR_PTR(-ENOMEM);
245
246 xprt->timeout = &xprt_rdma_bc_timeout;
247 xprt_set_bound(xprt);
248 xprt_set_connected(xprt);
249 xprt->bind_timeout = 0;
250 xprt->reestablish_timeout = 0;
251 xprt->idle_timeout = 0;
252
253 xprt->prot = XPRT_TRANSPORT_BC_RDMA;
254 xprt->ops = &xprt_rdma_bc_procs;
255
256 memcpy(&xprt->addr, args->dstaddr, args->addrlen);
257 xprt->addrlen = args->addrlen;
258 xprt_rdma_format_addresses(xprt, (struct sockaddr *)&xprt->addr);
259 xprt->resvport = 0;
260
261 xprt->max_payload = xprt_rdma_max_inline_read;
262
263 new_xprt = rpcx_to_rdmax(xprt);
264 new_xprt->rx_buf.rb_bc_max_requests = xprt->max_reqs;
265
266 xprt_get(xprt);
267 args->bc_xprt->xpt_bc_xprt = xprt;
268 xprt->bc_xprt = args->bc_xprt;
269
270 /* Final put for backchannel xprt is in __svc_rdma_free */
271 xprt_get(xprt);
272 return xprt;
273 }
274
275 struct xprt_class xprt_rdma_bc = {
276 .list = LIST_HEAD_INIT(xprt_rdma_bc.list),
277 .name = "rdma backchannel",
278 .owner = THIS_MODULE,
279 .ident = XPRT_TRANSPORT_BC_RDMA,
280 .setup = xprt_setup_rdma_bc,
281 };
282