Merge tag 'perf-urgent-for-mingo-20160418' of git://git.kernel.org/pub/scm/linux...
[linux-2.6-microblaze.git] / net / sunrpc / xprtrdma / svc_rdma_backchannel.c
1 /*
2  * Copyright (c) 2015 Oracle.  All rights reserved.
3  *
4  * Support for backward direction RPCs on RPC/RDMA (server-side).
5  */
6
7 #include <linux/sunrpc/svc_rdma.h>
8 #include "xprt_rdma.h"
9
10 #define RPCDBG_FACILITY RPCDBG_SVCXPRT
11
12 #undef SVCRDMA_BACKCHANNEL_DEBUG
13
14 int svc_rdma_handle_bc_reply(struct rpc_xprt *xprt, struct rpcrdma_msg *rmsgp,
15                              struct xdr_buf *rcvbuf)
16 {
17         struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
18         struct kvec *dst, *src = &rcvbuf->head[0];
19         struct rpc_rqst *req;
20         unsigned long cwnd;
21         u32 credits;
22         size_t len;
23         __be32 xid;
24         __be32 *p;
25         int ret;
26
27         p = (__be32 *)src->iov_base;
28         len = src->iov_len;
29         xid = rmsgp->rm_xid;
30
31 #ifdef SVCRDMA_BACKCHANNEL_DEBUG
32         pr_info("%s: xid=%08x, length=%zu\n",
33                 __func__, be32_to_cpu(xid), len);
34         pr_info("%s: RPC/RDMA: %*ph\n",
35                 __func__, (int)RPCRDMA_HDRLEN_MIN, rmsgp);
36         pr_info("%s:      RPC: %*ph\n",
37                 __func__, (int)len, p);
38 #endif
39
40         ret = -EAGAIN;
41         if (src->iov_len < 24)
42                 goto out_shortreply;
43
44         spin_lock_bh(&xprt->transport_lock);
45         req = xprt_lookup_rqst(xprt, xid);
46         if (!req)
47                 goto out_notfound;
48
49         dst = &req->rq_private_buf.head[0];
50         memcpy(&req->rq_private_buf, &req->rq_rcv_buf, sizeof(struct xdr_buf));
51         if (dst->iov_len < len)
52                 goto out_unlock;
53         memcpy(dst->iov_base, p, len);
54
55         credits = be32_to_cpu(rmsgp->rm_credit);
56         if (credits == 0)
57                 credits = 1;    /* don't deadlock */
58         else if (credits > r_xprt->rx_buf.rb_bc_max_requests)
59                 credits = r_xprt->rx_buf.rb_bc_max_requests;
60
61         cwnd = xprt->cwnd;
62         xprt->cwnd = credits << RPC_CWNDSHIFT;
63         if (xprt->cwnd > cwnd)
64                 xprt_release_rqst_cong(req->rq_task);
65
66         ret = 0;
67         xprt_complete_rqst(req->rq_task, rcvbuf->len);
68         rcvbuf->len = 0;
69
70 out_unlock:
71         spin_unlock_bh(&xprt->transport_lock);
72 out:
73         return ret;
74
75 out_shortreply:
76         dprintk("svcrdma: short bc reply: xprt=%p, len=%zu\n",
77                 xprt, src->iov_len);
78         goto out;
79
80 out_notfound:
81         dprintk("svcrdma: unrecognized bc reply: xprt=%p, xid=%08x\n",
82                 xprt, be32_to_cpu(xid));
83
84         goto out_unlock;
85 }
86
87 /* Send a backwards direction RPC call.
88  *
89  * Caller holds the connection's mutex and has already marshaled
90  * the RPC/RDMA request.
91  *
92  * This is similar to svc_rdma_reply, but takes an rpc_rqst
93  * instead, does not support chunks, and avoids blocking memory
94  * allocation.
95  *
96  * XXX: There is still an opportunity to block in svc_rdma_send()
97  * if there are no SQ entries to post the Send. This may occur if
98  * the adapter has a small maximum SQ depth.
99  */
100 static int svc_rdma_bc_sendto(struct svcxprt_rdma *rdma,
101                               struct rpc_rqst *rqst)
102 {
103         struct xdr_buf *sndbuf = &rqst->rq_snd_buf;
104         struct svc_rdma_op_ctxt *ctxt;
105         struct svc_rdma_req_map *vec;
106         struct ib_send_wr send_wr;
107         int ret;
108
109         vec = svc_rdma_get_req_map(rdma);
110         ret = svc_rdma_map_xdr(rdma, sndbuf, vec, false);
111         if (ret)
112                 goto out_err;
113
114         ret = svc_rdma_repost_recv(rdma, GFP_NOIO);
115         if (ret)
116                 goto out_err;
117
118         ctxt = svc_rdma_get_context(rdma);
119         ctxt->pages[0] = virt_to_page(rqst->rq_buffer);
120         ctxt->count = 1;
121
122         ctxt->direction = DMA_TO_DEVICE;
123         ctxt->sge[0].lkey = rdma->sc_pd->local_dma_lkey;
124         ctxt->sge[0].length = sndbuf->len;
125         ctxt->sge[0].addr =
126             ib_dma_map_page(rdma->sc_cm_id->device, ctxt->pages[0], 0,
127                             sndbuf->len, DMA_TO_DEVICE);
128         if (ib_dma_mapping_error(rdma->sc_cm_id->device, ctxt->sge[0].addr)) {
129                 ret = -EIO;
130                 goto out_unmap;
131         }
132         atomic_inc(&rdma->sc_dma_used);
133
134         memset(&send_wr, 0, sizeof(send_wr));
135         ctxt->cqe.done = svc_rdma_wc_send;
136         send_wr.wr_cqe = &ctxt->cqe;
137         send_wr.sg_list = ctxt->sge;
138         send_wr.num_sge = 1;
139         send_wr.opcode = IB_WR_SEND;
140         send_wr.send_flags = IB_SEND_SIGNALED;
141
142         ret = svc_rdma_send(rdma, &send_wr);
143         if (ret) {
144                 ret = -EIO;
145                 goto out_unmap;
146         }
147
148 out_err:
149         svc_rdma_put_req_map(rdma, vec);
150         dprintk("svcrdma: %s returns %d\n", __func__, ret);
151         return ret;
152
153 out_unmap:
154         svc_rdma_unmap_dma(ctxt);
155         svc_rdma_put_context(ctxt, 1);
156         goto out_err;
157 }
158
159 /* Server-side transport endpoint wants a whole page for its send
160  * buffer. The client RPC code constructs the RPC header in this
161  * buffer before it invokes ->send_request.
162  *
163  * Returns NULL if there was a temporary allocation failure.
164  */
165 static void *
166 xprt_rdma_bc_allocate(struct rpc_task *task, size_t size)
167 {
168         struct rpc_rqst *rqst = task->tk_rqstp;
169         struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt;
170         struct svcxprt_rdma *rdma;
171         struct page *page;
172
173         rdma = container_of(sxprt, struct svcxprt_rdma, sc_xprt);
174
175         /* Prevent an infinite loop: try to make this case work */
176         if (size > PAGE_SIZE)
177                 WARN_ONCE(1, "svcrdma: large bc buffer request (size %zu)\n",
178                           size);
179
180         page = alloc_page(RPCRDMA_DEF_GFP);
181         if (!page)
182                 return NULL;
183
184         return page_address(page);
185 }
186
187 static void
188 xprt_rdma_bc_free(void *buffer)
189 {
190         /* No-op: ctxt and page have already been freed. */
191 }
192
193 static int
194 rpcrdma_bc_send_request(struct svcxprt_rdma *rdma, struct rpc_rqst *rqst)
195 {
196         struct rpc_xprt *xprt = rqst->rq_xprt;
197         struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
198         struct rpcrdma_msg *headerp = (struct rpcrdma_msg *)rqst->rq_buffer;
199         int rc;
200
201         /* Space in the send buffer for an RPC/RDMA header is reserved
202          * via xprt->tsh_size.
203          */
204         headerp->rm_xid = rqst->rq_xid;
205         headerp->rm_vers = rpcrdma_version;
206         headerp->rm_credit = cpu_to_be32(r_xprt->rx_buf.rb_bc_max_requests);
207         headerp->rm_type = rdma_msg;
208         headerp->rm_body.rm_chunks[0] = xdr_zero;
209         headerp->rm_body.rm_chunks[1] = xdr_zero;
210         headerp->rm_body.rm_chunks[2] = xdr_zero;
211
212 #ifdef SVCRDMA_BACKCHANNEL_DEBUG
213         pr_info("%s: %*ph\n", __func__, 64, rqst->rq_buffer);
214 #endif
215
216         rc = svc_rdma_bc_sendto(rdma, rqst);
217         if (rc)
218                 goto drop_connection;
219         return rc;
220
221 drop_connection:
222         dprintk("svcrdma: failed to send bc call\n");
223         xprt_disconnect_done(xprt);
224         return -ENOTCONN;
225 }
226
227 /* Send an RPC call on the passive end of a transport
228  * connection.
229  */
230 static int
231 xprt_rdma_bc_send_request(struct rpc_task *task)
232 {
233         struct rpc_rqst *rqst = task->tk_rqstp;
234         struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt;
235         struct svcxprt_rdma *rdma;
236         int ret;
237
238         dprintk("svcrdma: sending bc call with xid: %08x\n",
239                 be32_to_cpu(rqst->rq_xid));
240
241         if (!mutex_trylock(&sxprt->xpt_mutex)) {
242                 rpc_sleep_on(&sxprt->xpt_bc_pending, task, NULL);
243                 if (!mutex_trylock(&sxprt->xpt_mutex))
244                         return -EAGAIN;
245                 rpc_wake_up_queued_task(&sxprt->xpt_bc_pending, task);
246         }
247
248         ret = -ENOTCONN;
249         rdma = container_of(sxprt, struct svcxprt_rdma, sc_xprt);
250         if (!test_bit(XPT_DEAD, &sxprt->xpt_flags))
251                 ret = rpcrdma_bc_send_request(rdma, rqst);
252
253         mutex_unlock(&sxprt->xpt_mutex);
254
255         if (ret < 0)
256                 return ret;
257         return 0;
258 }
259
260 static void
261 xprt_rdma_bc_close(struct rpc_xprt *xprt)
262 {
263         dprintk("svcrdma: %s: xprt %p\n", __func__, xprt);
264 }
265
266 static void
267 xprt_rdma_bc_put(struct rpc_xprt *xprt)
268 {
269         dprintk("svcrdma: %s: xprt %p\n", __func__, xprt);
270
271         xprt_free(xprt);
272         module_put(THIS_MODULE);
273 }
274
275 static struct rpc_xprt_ops xprt_rdma_bc_procs = {
276         .reserve_xprt           = xprt_reserve_xprt_cong,
277         .release_xprt           = xprt_release_xprt_cong,
278         .alloc_slot             = xprt_alloc_slot,
279         .release_request        = xprt_release_rqst_cong,
280         .buf_alloc              = xprt_rdma_bc_allocate,
281         .buf_free               = xprt_rdma_bc_free,
282         .send_request           = xprt_rdma_bc_send_request,
283         .set_retrans_timeout    = xprt_set_retrans_timeout_def,
284         .close                  = xprt_rdma_bc_close,
285         .destroy                = xprt_rdma_bc_put,
286         .print_stats            = xprt_rdma_print_stats
287 };
288
289 static const struct rpc_timeout xprt_rdma_bc_timeout = {
290         .to_initval = 60 * HZ,
291         .to_maxval = 60 * HZ,
292 };
293
294 /* It shouldn't matter if the number of backchannel session slots
295  * doesn't match the number of RPC/RDMA credits. That just means
296  * one or the other will have extra slots that aren't used.
297  */
298 static struct rpc_xprt *
299 xprt_setup_rdma_bc(struct xprt_create *args)
300 {
301         struct rpc_xprt *xprt;
302         struct rpcrdma_xprt *new_xprt;
303
304         if (args->addrlen > sizeof(xprt->addr)) {
305                 dprintk("RPC:       %s: address too large\n", __func__);
306                 return ERR_PTR(-EBADF);
307         }
308
309         xprt = xprt_alloc(args->net, sizeof(*new_xprt),
310                           RPCRDMA_MAX_BC_REQUESTS,
311                           RPCRDMA_MAX_BC_REQUESTS);
312         if (!xprt) {
313                 dprintk("RPC:       %s: couldn't allocate rpc_xprt\n",
314                         __func__);
315                 return ERR_PTR(-ENOMEM);
316         }
317
318         xprt->timeout = &xprt_rdma_bc_timeout;
319         xprt_set_bound(xprt);
320         xprt_set_connected(xprt);
321         xprt->bind_timeout = RPCRDMA_BIND_TO;
322         xprt->reestablish_timeout = RPCRDMA_INIT_REEST_TO;
323         xprt->idle_timeout = RPCRDMA_IDLE_DISC_TO;
324
325         xprt->prot = XPRT_TRANSPORT_BC_RDMA;
326         xprt->tsh_size = RPCRDMA_HDRLEN_MIN / sizeof(__be32);
327         xprt->ops = &xprt_rdma_bc_procs;
328
329         memcpy(&xprt->addr, args->dstaddr, args->addrlen);
330         xprt->addrlen = args->addrlen;
331         xprt_rdma_format_addresses(xprt, (struct sockaddr *)&xprt->addr);
332         xprt->resvport = 0;
333
334         xprt->max_payload = xprt_rdma_max_inline_read;
335
336         new_xprt = rpcx_to_rdmax(xprt);
337         new_xprt->rx_buf.rb_bc_max_requests = xprt->max_reqs;
338
339         xprt_get(xprt);
340         args->bc_xprt->xpt_bc_xprt = xprt;
341         xprt->bc_xprt = args->bc_xprt;
342
343         if (!try_module_get(THIS_MODULE))
344                 goto out_fail;
345
346         /* Final put for backchannel xprt is in __svc_rdma_free */
347         xprt_get(xprt);
348         return xprt;
349
350 out_fail:
351         xprt_rdma_free_addresses(xprt);
352         args->bc_xprt->xpt_bc_xprt = NULL;
353         xprt_put(xprt);
354         xprt_free(xprt);
355         return ERR_PTR(-EINVAL);
356 }
357
358 struct xprt_class xprt_rdma_bc = {
359         .list                   = LIST_HEAD_INIT(xprt_rdma_bc.list),
360         .name                   = "rdma backchannel",
361         .owner                  = THIS_MODULE,
362         .ident                  = XPRT_TRANSPORT_BC_RDMA,
363         .setup                  = xprt_setup_rdma_bc,
364 };