1 /*
2  * Copyright (c) 2006, 2017 Oracle and/or its affiliates. All rights reserved.
3  *
4  * This software is available to you under a choice of one of two
5  * licenses.  You may choose to be licensed under the terms of the GNU
6  * General Public License (GPL) Version 2, available from the file
7  * COPYING in the main directory of this source tree, or the
8  * OpenIB.org BSD license below:
9  *
10  *     Redistribution and use in source and binary forms, with or
11  *     without modification, are permitted provided that the following
12  *     conditions are met:
13  *
14  *      - Redistributions of source code must retain the above
15  *        copyright notice, this list of conditions and the following
16  *        disclaimer.
17  *
18  *      - Redistributions in binary form must reproduce the above
19  *        copyright notice, this list of conditions and the following
20  *        disclaimer in the documentation and/or other materials
21  *        provided with the distribution.
22  *
23  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
24  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
25  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
26  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
27  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
28  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
29  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
30  * SOFTWARE.
31  *
32  */
33 #include <linux/kernel.h>
34 #include <linux/slab.h>
35 #include <net/tcp.h>
36 
37 #include "rds.h"
38 #include "tcp.h"
39 
40 static struct kmem_cache *rds_tcp_incoming_slab;
41 
rds_tcp_inc_purge(struct rds_incoming * inc)42 static void rds_tcp_inc_purge(struct rds_incoming *inc)
43 {
44 	struct rds_tcp_incoming *tinc;
45 	tinc = container_of(inc, struct rds_tcp_incoming, ti_inc);
46 	rdsdebug("purging tinc %p inc %p\n", tinc, inc);
47 	skb_queue_purge(&tinc->ti_skb_list);
48 }
49 
rds_tcp_inc_free(struct rds_incoming * inc)50 void rds_tcp_inc_free(struct rds_incoming *inc)
51 {
52 	struct rds_tcp_incoming *tinc;
53 	tinc = container_of(inc, struct rds_tcp_incoming, ti_inc);
54 	rds_tcp_inc_purge(inc);
55 	rdsdebug("freeing tinc %p inc %p\n", tinc, inc);
56 	kmem_cache_free(rds_tcp_incoming_slab, tinc);
57 }
58 
59 /*
60  * this is pretty lame, but, whatever.
61  */
rds_tcp_inc_copy_to_user(struct rds_incoming * inc,struct iov_iter * to)62 int rds_tcp_inc_copy_to_user(struct rds_incoming *inc, struct iov_iter *to)
63 {
64 	struct rds_tcp_incoming *tinc;
65 	struct sk_buff *skb;
66 	int ret = 0;
67 
68 	if (!iov_iter_count(to))
69 		goto out;
70 
71 	tinc = container_of(inc, struct rds_tcp_incoming, ti_inc);
72 
73 	skb_queue_walk(&tinc->ti_skb_list, skb) {
74 		unsigned long to_copy, skb_off;
75 		for (skb_off = 0; skb_off < skb->len; skb_off += to_copy) {
76 			to_copy = iov_iter_count(to);
77 			to_copy = min(to_copy, skb->len - skb_off);
78 
79 			if (skb_copy_datagram_iter(skb, skb_off, to, to_copy))
80 				return -EFAULT;
81 
82 			rds_stats_add(s_copy_to_user, to_copy);
83 			ret += to_copy;
84 
85 			if (!iov_iter_count(to))
86 				goto out;
87 		}
88 	}
89 out:
90 	return ret;
91 }
92 
93 /*
94  * We have a series of skbs that have fragmented pieces of the congestion
95  * bitmap.  They must add up to the exact size of the congestion bitmap.  We
96  * use the skb helpers to copy those into the pages that make up the in-memory
97  * congestion bitmap for the remote address of this connection.  We then tell
98  * the congestion core that the bitmap has been changed so that it can wake up
99  * sleepers.
100  *
101  * This is racing with sending paths which are using test_bit to see if the
102  * bitmap indicates that their recipient is congested.
103  */
104 
rds_tcp_cong_recv(struct rds_connection * conn,struct rds_tcp_incoming * tinc)105 static void rds_tcp_cong_recv(struct rds_connection *conn,
106 			      struct rds_tcp_incoming *tinc)
107 {
108 	struct sk_buff *skb;
109 	unsigned int to_copy, skb_off;
110 	unsigned int map_off;
111 	unsigned int map_page;
112 	struct rds_cong_map *map;
113 	int ret;
114 
115 	/* catch completely corrupt packets */
116 	if (be32_to_cpu(tinc->ti_inc.i_hdr.h_len) != RDS_CONG_MAP_BYTES)
117 		return;
118 
119 	map_page = 0;
120 	map_off = 0;
121 	map = conn->c_fcong;
122 
123 	skb_queue_walk(&tinc->ti_skb_list, skb) {
124 		skb_off = 0;
125 		while (skb_off < skb->len) {
126 			to_copy = min_t(unsigned int, PAGE_SIZE - map_off,
127 					skb->len - skb_off);
128 
129 			BUG_ON(map_page >= RDS_CONG_MAP_PAGES);
130 
131 			/* only returns 0 or -error */
132 			ret = skb_copy_bits(skb, skb_off,
133 				(void *)map->m_page_addrs[map_page] + map_off,
134 				to_copy);
135 			BUG_ON(ret != 0);
136 
137 			skb_off += to_copy;
138 			map_off += to_copy;
139 			if (map_off == PAGE_SIZE) {
140 				map_off = 0;
141 				map_page++;
142 			}
143 		}
144 	}
145 
146 	rds_cong_map_updated(map, ~(u64) 0);
147 }
148 
149 struct rds_tcp_desc_arg {
150 	struct rds_conn_path *conn_path;
151 	gfp_t gfp;
152 };
153 
rds_tcp_data_recv(read_descriptor_t * desc,struct sk_buff * skb,unsigned int offset,size_t len)154 static int rds_tcp_data_recv(read_descriptor_t *desc, struct sk_buff *skb,
155 			     unsigned int offset, size_t len)
156 {
157 	struct rds_tcp_desc_arg *arg = desc->arg.data;
158 	struct rds_conn_path *cp = arg->conn_path;
159 	struct rds_tcp_connection *tc = cp->cp_transport_data;
160 	struct rds_tcp_incoming *tinc = tc->t_tinc;
161 	struct sk_buff *clone;
162 	size_t left = len, to_copy;
163 
164 	rdsdebug("tcp data tc %p skb %p offset %u len %zu\n", tc, skb, offset,
165 		 len);
166 
167 	/*
168 	 * tcp_read_sock() interprets partial progress as an indication to stop
169 	 * processing.
170 	 */
171 	while (left) {
172 		if (!tinc) {
173 			tinc = kmem_cache_alloc(rds_tcp_incoming_slab,
174 						arg->gfp);
175 			if (!tinc) {
176 				desc->error = -ENOMEM;
177 				goto out;
178 			}
179 			tc->t_tinc = tinc;
180 			rdsdebug("allocated tinc %p\n", tinc);
181 			rds_inc_path_init(&tinc->ti_inc, cp,
182 					  &cp->cp_conn->c_faddr);
183 			tinc->ti_inc.i_rx_lat_trace[RDS_MSG_RX_HDR] =
184 					local_clock();
185 
186 			/*
187 			 * XXX * we might be able to use the __ variants when
188 			 * we've already serialized at a higher level.
189 			 */
190 			skb_queue_head_init(&tinc->ti_skb_list);
191 		}
192 
193 		if (left && tc->t_tinc_hdr_rem) {
194 			to_copy = min(tc->t_tinc_hdr_rem, left);
195 			rdsdebug("copying %zu header from skb %p\n", to_copy,
196 				 skb);
197 			skb_copy_bits(skb, offset,
198 				      (char *)&tinc->ti_inc.i_hdr +
199 						sizeof(struct rds_header) -
200 						tc->t_tinc_hdr_rem,
201 				      to_copy);
202 			tc->t_tinc_hdr_rem -= to_copy;
203 			left -= to_copy;
204 			offset += to_copy;
205 
206 			if (tc->t_tinc_hdr_rem == 0) {
207 				/* could be 0 for a 0 len message */
208 				tc->t_tinc_data_rem =
209 					be32_to_cpu(tinc->ti_inc.i_hdr.h_len);
210 				tinc->ti_inc.i_rx_lat_trace[RDS_MSG_RX_START] =
211 					local_clock();
212 			}
213 		}
214 
215 		if (left && tc->t_tinc_data_rem) {
216 			to_copy = min(tc->t_tinc_data_rem, left);
217 
218 			clone = pskb_extract(skb, offset, to_copy, arg->gfp);
219 			if (!clone) {
220 				desc->error = -ENOMEM;
221 				goto out;
222 			}
223 
224 			skb_queue_tail(&tinc->ti_skb_list, clone);
225 
226 			rdsdebug("skb %p data %p len %d off %u to_copy %zu -> "
227 				 "clone %p data %p len %d\n",
228 				 skb, skb->data, skb->len, offset, to_copy,
229 				 clone, clone->data, clone->len);
230 
231 			tc->t_tinc_data_rem -= to_copy;
232 			left -= to_copy;
233 			offset += to_copy;
234 		}
235 
236 		if (tc->t_tinc_hdr_rem == 0 && tc->t_tinc_data_rem == 0) {
237 			struct rds_connection *conn = cp->cp_conn;
238 
239 			if (tinc->ti_inc.i_hdr.h_flags == RDS_FLAG_CONG_BITMAP)
240 				rds_tcp_cong_recv(conn, tinc);
241 			else
242 				rds_recv_incoming(conn, &conn->c_faddr,
243 						  &conn->c_laddr,
244 						  &tinc->ti_inc,
245 						  arg->gfp);
246 
247 			tc->t_tinc_hdr_rem = sizeof(struct rds_header);
248 			tc->t_tinc_data_rem = 0;
249 			tc->t_tinc = NULL;
250 			rds_inc_put(&tinc->ti_inc);
251 			tinc = NULL;
252 		}
253 	}
254 out:
255 	rdsdebug("returning len %zu left %zu skb len %d rx queue depth %d\n",
256 		 len, left, skb->len,
257 		 skb_queue_len(&tc->t_sock->sk->sk_receive_queue));
258 	return len - left;
259 }
260 
261 /* the caller has to hold the sock lock */
rds_tcp_read_sock(struct rds_conn_path * cp,gfp_t gfp)262 static int rds_tcp_read_sock(struct rds_conn_path *cp, gfp_t gfp)
263 {
264 	struct rds_tcp_connection *tc = cp->cp_transport_data;
265 	struct socket *sock = tc->t_sock;
266 	read_descriptor_t desc;
267 	struct rds_tcp_desc_arg arg;
268 
269 	/* It's like glib in the kernel! */
270 	arg.conn_path = cp;
271 	arg.gfp = gfp;
272 	desc.arg.data = &arg;
273 	desc.error = 0;
274 	desc.count = 1; /* give more than one skb per call */
275 
276 	tcp_read_sock(sock->sk, &desc, rds_tcp_data_recv);
277 	rdsdebug("tcp_read_sock for tc %p gfp 0x%x returned %d\n", tc, gfp,
278 		 desc.error);
279 
280 	return desc.error;
281 }
282 
283 /*
284  * We hold the sock lock to serialize our rds_tcp_recv->tcp_read_sock from
285  * data_ready.
286  *
287  * if we fail to allocate we're in trouble.. blindly wait some time before
288  * trying again to see if the VM can free up something for us.
289  */
rds_tcp_recv_path(struct rds_conn_path * cp)290 int rds_tcp_recv_path(struct rds_conn_path *cp)
291 {
292 	struct rds_tcp_connection *tc = cp->cp_transport_data;
293 	struct socket *sock = tc->t_sock;
294 	int ret = 0;
295 
296 	rdsdebug("recv worker path [%d] tc %p sock %p\n",
297 		 cp->cp_index, tc, sock);
298 
299 	lock_sock(sock->sk);
300 	ret = rds_tcp_read_sock(cp, GFP_KERNEL);
301 	release_sock(sock->sk);
302 
303 	return ret;
304 }
305 
rds_tcp_data_ready(struct sock * sk)306 void rds_tcp_data_ready(struct sock *sk)
307 {
308 	void (*ready)(struct sock *sk);
309 	struct rds_conn_path *cp;
310 	struct rds_tcp_connection *tc;
311 
312 	rdsdebug("data ready sk %p\n", sk);
313 
314 	read_lock_bh(&sk->sk_callback_lock);
315 	cp = sk->sk_user_data;
316 	if (!cp) { /* check for teardown race */
317 		ready = sk->sk_data_ready;
318 		goto out;
319 	}
320 
321 	tc = cp->cp_transport_data;
322 	ready = tc->t_orig_data_ready;
323 	rds_tcp_stats_inc(s_tcp_data_ready_calls);
324 
325 	if (rds_tcp_read_sock(cp, GFP_ATOMIC) == -ENOMEM) {
326 		rcu_read_lock();
327 		if (!rds_destroy_pending(cp->cp_conn))
328 			queue_delayed_work(rds_wq, &cp->cp_recv_w, 0);
329 		rcu_read_unlock();
330 	}
331 out:
332 	read_unlock_bh(&sk->sk_callback_lock);
333 	ready(sk);
334 }
335 
rds_tcp_recv_init(void)336 int rds_tcp_recv_init(void)
337 {
338 	rds_tcp_incoming_slab = kmem_cache_create("rds_tcp_incoming",
339 					sizeof(struct rds_tcp_incoming),
340 					0, 0, NULL);
341 	if (!rds_tcp_incoming_slab)
342 		return -ENOMEM;
343 	return 0;
344 }
345 
rds_tcp_recv_exit(void)346 void rds_tcp_recv_exit(void)
347 {
348 	kmem_cache_destroy(rds_tcp_incoming_slab);
349 }
350