2 * Copyright (c) 2015 Oracle. All rights reserved.
4 * Support for backward direction RPCs on RPC/RDMA (server-side).
7 #include <linux/module.h>
8 #include <linux/sunrpc/svc_rdma.h>
11 #define RPCDBG_FACILITY RPCDBG_SVCXPRT
13 #undef SVCRDMA_BACKCHANNEL_DEBUG
16 * svc_rdma_handle_bc_reply - Process incoming backchannel reply
17 * @xprt: controlling backchannel transport
18 * @rdma_resp: pointer to incoming transport header
19 * @rcvbuf: XDR buffer into which to decode the reply
22 * %0 if @rcvbuf is filled in, xprt_complete_rqst called,
23 * %-EAGAIN if server should call ->recvfrom again.
25 int svc_rdma_handle_bc_reply(struct rpc_xprt *xprt, __be32 *rdma_resp,
26 struct xdr_buf *rcvbuf)
28 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
29 struct kvec *dst, *src = &rcvbuf->head[0];
38 p = (__be32 *)src->iov_base;
42 #ifdef SVCRDMA_BACKCHANNEL_DEBUG
43 pr_info("%s: xid=%08x, length=%zu\n",
44 __func__, be32_to_cpu(xid), len);
45 pr_info("%s: RPC/RDMA: %*ph\n",
46 __func__, (int)RPCRDMA_HDRLEN_MIN, rdma_resp);
47 pr_info("%s: RPC: %*ph\n",
48 __func__, (int)len, p);
52 if (src->iov_len < 24)
55 spin_lock(&xprt->recv_lock);
56 req = xprt_lookup_rqst(xprt, xid);
60 dst = &req->rq_private_buf.head[0];
61 memcpy(&req->rq_private_buf, &req->rq_rcv_buf, sizeof(struct xdr_buf));
62 if (dst->iov_len < len)
64 memcpy(dst->iov_base, p, len);
66 credits = be32_to_cpup(rdma_resp + 2);
68 credits = 1; /* don't deadlock */
69 else if (credits > r_xprt->rx_buf.rb_bc_max_requests)
70 credits = r_xprt->rx_buf.rb_bc_max_requests;
72 spin_lock_bh(&xprt->transport_lock);
74 xprt->cwnd = credits << RPC_CWNDSHIFT;
75 if (xprt->cwnd > cwnd)
76 xprt_release_rqst_cong(req->rq_task);
77 spin_unlock_bh(&xprt->transport_lock);
81 xprt_complete_rqst(req->rq_task, rcvbuf->len);
85 spin_unlock(&xprt->recv_lock);
90 dprintk("svcrdma: short bc reply: xprt=%p, len=%zu\n",
95 dprintk("svcrdma: unrecognized bc reply: xprt=%p, xid=%08x\n",
96 xprt, be32_to_cpu(xid));
101 /* Send a backwards direction RPC call.
103 * Caller holds the connection's mutex and has already marshaled
104 * the RPC/RDMA request.
106 * This is similar to svc_rdma_send_reply_msg, but takes a struct
107 * rpc_rqst instead, does not support chunks, and avoids blocking
110 * XXX: There is still an opportunity to block in svc_rdma_send()
111 * if there are no SQ entries to post the Send. This may occur if
112 * the adapter has a small maximum SQ depth.
114 static int svc_rdma_bc_sendto(struct svcxprt_rdma *rdma,
115 struct rpc_rqst *rqst)
117 struct svc_rdma_op_ctxt *ctxt;
120 ctxt = svc_rdma_get_context(rdma);
122 /* rpcrdma_bc_send_request builds the transport header and
123 * the backchannel RPC message in the same buffer. Thus only
124 * one SGE is needed to send both.
126 ret = svc_rdma_map_reply_hdr(rdma, ctxt, rqst->rq_buffer,
127 rqst->rq_snd_buf.len);
131 ret = svc_rdma_repost_recv(rdma, GFP_NOIO);
135 ret = svc_rdma_post_send_wr(rdma, ctxt, 1, 0);
140 dprintk("svcrdma: %s returns %d\n", __func__, ret);
144 svc_rdma_unmap_dma(ctxt);
145 svc_rdma_put_context(ctxt, 1);
150 /* Server-side transport endpoint wants a whole page for its send
151 * buffer. The client RPC code constructs the RPC header in this
152 * buffer before it invokes ->send_request.
155 xprt_rdma_bc_allocate(struct rpc_task *task)
157 struct rpc_rqst *rqst = task->tk_rqstp;
158 size_t size = rqst->rq_callsize;
161 if (size > PAGE_SIZE) {
162 WARN_ONCE(1, "svcrdma: large bc buffer request (size %zu)\n",
167 /* svc_rdma_sendto releases this page */
168 page = alloc_page(RPCRDMA_DEF_GFP);
171 rqst->rq_buffer = page_address(page);
173 rqst->rq_rbuffer = kmalloc(rqst->rq_rcvsize, RPCRDMA_DEF_GFP);
174 if (!rqst->rq_rbuffer) {
182 xprt_rdma_bc_free(struct rpc_task *task)
184 struct rpc_rqst *rqst = task->tk_rqstp;
186 kfree(rqst->rq_rbuffer);
190 rpcrdma_bc_send_request(struct svcxprt_rdma *rdma, struct rpc_rqst *rqst)
192 struct rpc_xprt *xprt = rqst->rq_xprt;
193 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
197 /* Space in the send buffer for an RPC/RDMA header is reserved
198 * via xprt->tsh_size.
202 *p++ = rpcrdma_version;
203 *p++ = cpu_to_be32(r_xprt->rx_buf.rb_bc_max_requests);
209 #ifdef SVCRDMA_BACKCHANNEL_DEBUG
210 pr_info("%s: %*ph\n", __func__, 64, rqst->rq_buffer);
213 rc = svc_rdma_bc_sendto(rdma, rqst);
215 goto drop_connection;
219 dprintk("svcrdma: failed to send bc call\n");
220 xprt_disconnect_done(xprt);
224 /* Send an RPC call on the passive end of a transport
228 xprt_rdma_bc_send_request(struct rpc_task *task)
230 struct rpc_rqst *rqst = task->tk_rqstp;
231 struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt;
232 struct svcxprt_rdma *rdma;
235 dprintk("svcrdma: sending bc call with xid: %08x\n",
236 be32_to_cpu(rqst->rq_xid));
238 if (!mutex_trylock(&sxprt->xpt_mutex)) {
239 rpc_sleep_on(&sxprt->xpt_bc_pending, task, NULL);
240 if (!mutex_trylock(&sxprt->xpt_mutex))
242 rpc_wake_up_queued_task(&sxprt->xpt_bc_pending, task);
246 rdma = container_of(sxprt, struct svcxprt_rdma, sc_xprt);
247 if (!test_bit(XPT_DEAD, &sxprt->xpt_flags))
248 ret = rpcrdma_bc_send_request(rdma, rqst);
250 mutex_unlock(&sxprt->xpt_mutex);
258 xprt_rdma_bc_close(struct rpc_xprt *xprt)
260 dprintk("svcrdma: %s: xprt %p\n", __func__, xprt);
264 xprt_rdma_bc_put(struct rpc_xprt *xprt)
266 dprintk("svcrdma: %s: xprt %p\n", __func__, xprt);
269 module_put(THIS_MODULE);
272 static const struct rpc_xprt_ops xprt_rdma_bc_procs = {
273 .reserve_xprt = xprt_reserve_xprt_cong,
274 .release_xprt = xprt_release_xprt_cong,
275 .alloc_slot = xprt_alloc_slot,
276 .release_request = xprt_release_rqst_cong,
277 .buf_alloc = xprt_rdma_bc_allocate,
278 .buf_free = xprt_rdma_bc_free,
279 .send_request = xprt_rdma_bc_send_request,
280 .set_retrans_timeout = xprt_set_retrans_timeout_def,
281 .close = xprt_rdma_bc_close,
282 .destroy = xprt_rdma_bc_put,
283 .print_stats = xprt_rdma_print_stats
286 static const struct rpc_timeout xprt_rdma_bc_timeout = {
287 .to_initval = 60 * HZ,
288 .to_maxval = 60 * HZ,
291 /* It shouldn't matter if the number of backchannel session slots
292 * doesn't match the number of RPC/RDMA credits. That just means
293 * one or the other will have extra slots that aren't used.
295 static struct rpc_xprt *
296 xprt_setup_rdma_bc(struct xprt_create *args)
298 struct rpc_xprt *xprt;
299 struct rpcrdma_xprt *new_xprt;
301 if (args->addrlen > sizeof(xprt->addr)) {
302 dprintk("RPC: %s: address too large\n", __func__);
303 return ERR_PTR(-EBADF);
306 xprt = xprt_alloc(args->net, sizeof(*new_xprt),
307 RPCRDMA_MAX_BC_REQUESTS,
308 RPCRDMA_MAX_BC_REQUESTS);
310 dprintk("RPC: %s: couldn't allocate rpc_xprt\n",
312 return ERR_PTR(-ENOMEM);
315 xprt->timeout = &xprt_rdma_bc_timeout;
316 xprt_set_bound(xprt);
317 xprt_set_connected(xprt);
318 xprt->bind_timeout = RPCRDMA_BIND_TO;
319 xprt->reestablish_timeout = RPCRDMA_INIT_REEST_TO;
320 xprt->idle_timeout = RPCRDMA_IDLE_DISC_TO;
322 xprt->prot = XPRT_TRANSPORT_BC_RDMA;
323 xprt->tsh_size = RPCRDMA_HDRLEN_MIN / sizeof(__be32);
324 xprt->ops = &xprt_rdma_bc_procs;
326 memcpy(&xprt->addr, args->dstaddr, args->addrlen);
327 xprt->addrlen = args->addrlen;
328 xprt_rdma_format_addresses(xprt, (struct sockaddr *)&xprt->addr);
331 xprt->max_payload = xprt_rdma_max_inline_read;
333 new_xprt = rpcx_to_rdmax(xprt);
334 new_xprt->rx_buf.rb_bc_max_requests = xprt->max_reqs;
337 args->bc_xprt->xpt_bc_xprt = xprt;
338 xprt->bc_xprt = args->bc_xprt;
340 if (!try_module_get(THIS_MODULE))
343 /* Final put for backchannel xprt is in __svc_rdma_free */
348 xprt_rdma_free_addresses(xprt);
349 args->bc_xprt->xpt_bc_xprt = NULL;
350 args->bc_xprt->xpt_bc_xps = NULL;
353 return ERR_PTR(-EINVAL);
356 struct xprt_class xprt_rdma_bc = {
357 .list = LIST_HEAD_INIT(xprt_rdma_bc.list),
358 .name = "rdma backchannel",
359 .owner = THIS_MODULE,
360 .ident = XPRT_TRANSPORT_BC_RDMA,
361 .setup = xprt_setup_rdma_bc,