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Linux/net/rds/tcp_recv.c

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  1 /*
  2  * Copyright (c) 2006 Oracle.  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 
 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 
 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  */
 62 int rds_tcp_inc_copy_to_user(struct rds_incoming *inc, struct iovec *first_iov,
 63                              size_t size)
 64 {
 65         struct rds_tcp_incoming *tinc;
 66         struct iovec *iov, tmp;
 67         struct sk_buff *skb;
 68         unsigned long to_copy, skb_off;
 69         int ret = 0;
 70 
 71         if (size == 0)
 72                 goto out;
 73 
 74         tinc = container_of(inc, struct rds_tcp_incoming, ti_inc);
 75         iov = first_iov;
 76         tmp = *iov;
 77 
 78         skb_queue_walk(&tinc->ti_skb_list, skb) {
 79                 skb_off = 0;
 80                 while (skb_off < skb->len) {
 81                         while (tmp.iov_len == 0) {
 82                                 iov++;
 83                                 tmp = *iov;
 84                         }
 85 
 86                         to_copy = min(tmp.iov_len, size);
 87                         to_copy = min(to_copy, skb->len - skb_off);
 88 
 89                         rdsdebug("ret %d size %zu skb %p skb_off %lu "
 90                                  "skblen %d iov_base %p iov_len %zu cpy %lu\n",
 91                                  ret, size, skb, skb_off, skb->len,
 92                                  tmp.iov_base, tmp.iov_len, to_copy);
 93 
 94                         /* modifies tmp as it copies */
 95                         if (skb_copy_datagram_iovec(skb, skb_off, &tmp,
 96                                                     to_copy)) {
 97                                 ret = -EFAULT;
 98                                 goto out;
 99                         }
100 
101                         rds_stats_add(s_copy_to_user, to_copy);
102                         size -= to_copy;
103                         ret += to_copy;
104                         skb_off += to_copy;
105                         if (size == 0)
106                                 goto out;
107                 }
108         }
109 out:
110         return ret;
111 }
112 
113 /*
114  * We have a series of skbs that have fragmented pieces of the congestion
115  * bitmap.  They must add up to the exact size of the congestion bitmap.  We
116  * use the skb helpers to copy those into the pages that make up the in-memory
117  * congestion bitmap for the remote address of this connection.  We then tell
118  * the congestion core that the bitmap has been changed so that it can wake up
119  * sleepers.
120  *
121  * This is racing with sending paths which are using test_bit to see if the
122  * bitmap indicates that their recipient is congested.
123  */
124 
125 static void rds_tcp_cong_recv(struct rds_connection *conn,
126                               struct rds_tcp_incoming *tinc)
127 {
128         struct sk_buff *skb;
129         unsigned int to_copy, skb_off;
130         unsigned int map_off;
131         unsigned int map_page;
132         struct rds_cong_map *map;
133         int ret;
134 
135         /* catch completely corrupt packets */
136         if (be32_to_cpu(tinc->ti_inc.i_hdr.h_len) != RDS_CONG_MAP_BYTES)
137                 return;
138 
139         map_page = 0;
140         map_off = 0;
141         map = conn->c_fcong;
142 
143         skb_queue_walk(&tinc->ti_skb_list, skb) {
144                 skb_off = 0;
145                 while (skb_off < skb->len) {
146                         to_copy = min_t(unsigned int, PAGE_SIZE - map_off,
147                                         skb->len - skb_off);
148 
149                         BUG_ON(map_page >= RDS_CONG_MAP_PAGES);
150 
151                         /* only returns 0 or -error */
152                         ret = skb_copy_bits(skb, skb_off,
153                                 (void *)map->m_page_addrs[map_page] + map_off,
154                                 to_copy);
155                         BUG_ON(ret != 0);
156 
157                         skb_off += to_copy;
158                         map_off += to_copy;
159                         if (map_off == PAGE_SIZE) {
160                                 map_off = 0;
161                                 map_page++;
162                         }
163                 }
164         }
165 
166         rds_cong_map_updated(map, ~(u64) 0);
167 }
168 
169 struct rds_tcp_desc_arg {
170         struct rds_connection *conn;
171         gfp_t gfp;
172 };
173 
174 static int rds_tcp_data_recv(read_descriptor_t *desc, struct sk_buff *skb,
175                              unsigned int offset, size_t len)
176 {
177         struct rds_tcp_desc_arg *arg = desc->arg.data;
178         struct rds_connection *conn = arg->conn;
179         struct rds_tcp_connection *tc = conn->c_transport_data;
180         struct rds_tcp_incoming *tinc = tc->t_tinc;
181         struct sk_buff *clone;
182         size_t left = len, to_copy;
183 
184         rdsdebug("tcp data tc %p skb %p offset %u len %zu\n", tc, skb, offset,
185                  len);
186 
187         /*
188          * tcp_read_sock() interprets partial progress as an indication to stop
189          * processing.
190          */
191         while (left) {
192                 if (!tinc) {
193                         tinc = kmem_cache_alloc(rds_tcp_incoming_slab,
194                                                 arg->gfp);
195                         if (!tinc) {
196                                 desc->error = -ENOMEM;
197                                 goto out;
198                         }
199                         tc->t_tinc = tinc;
200                         rdsdebug("alloced tinc %p\n", tinc);
201                         rds_inc_init(&tinc->ti_inc, conn, conn->c_faddr);
202                         /*
203                          * XXX * we might be able to use the __ variants when
204                          * we've already serialized at a higher level.
205                          */
206                         skb_queue_head_init(&tinc->ti_skb_list);
207                 }
208 
209                 if (left && tc->t_tinc_hdr_rem) {
210                         to_copy = min(tc->t_tinc_hdr_rem, left);
211                         rdsdebug("copying %zu header from skb %p\n", to_copy,
212                                  skb);
213                         skb_copy_bits(skb, offset,
214                                       (char *)&tinc->ti_inc.i_hdr +
215                                                 sizeof(struct rds_header) -
216                                                 tc->t_tinc_hdr_rem,
217                                       to_copy);
218                         tc->t_tinc_hdr_rem -= to_copy;
219                         left -= to_copy;
220                         offset += to_copy;
221 
222                         if (tc->t_tinc_hdr_rem == 0) {
223                                 /* could be 0 for a 0 len message */
224                                 tc->t_tinc_data_rem =
225                                         be32_to_cpu(tinc->ti_inc.i_hdr.h_len);
226                         }
227                 }
228 
229                 if (left && tc->t_tinc_data_rem) {
230                         clone = skb_clone(skb, arg->gfp);
231                         if (!clone) {
232                                 desc->error = -ENOMEM;
233                                 goto out;
234                         }
235 
236                         to_copy = min(tc->t_tinc_data_rem, left);
237                         pskb_pull(clone, offset);
238                         pskb_trim(clone, to_copy);
239                         skb_queue_tail(&tinc->ti_skb_list, clone);
240 
241                         rdsdebug("skb %p data %p len %d off %u to_copy %zu -> "
242                                  "clone %p data %p len %d\n",
243                                  skb, skb->data, skb->len, offset, to_copy,
244                                  clone, clone->data, clone->len);
245 
246                         tc->t_tinc_data_rem -= to_copy;
247                         left -= to_copy;
248                         offset += to_copy;
249                 }
250 
251                 if (tc->t_tinc_hdr_rem == 0 && tc->t_tinc_data_rem == 0) {
252                         if (tinc->ti_inc.i_hdr.h_flags == RDS_FLAG_CONG_BITMAP)
253                                 rds_tcp_cong_recv(conn, tinc);
254                         else
255                                 rds_recv_incoming(conn, conn->c_faddr,
256                                                   conn->c_laddr, &tinc->ti_inc,
257                                                   arg->gfp);
258 
259                         tc->t_tinc_hdr_rem = sizeof(struct rds_header);
260                         tc->t_tinc_data_rem = 0;
261                         tc->t_tinc = NULL;
262                         rds_inc_put(&tinc->ti_inc);
263                         tinc = NULL;
264                 }
265         }
266 out:
267         rdsdebug("returning len %zu left %zu skb len %d rx queue depth %d\n",
268                  len, left, skb->len,
269                  skb_queue_len(&tc->t_sock->sk->sk_receive_queue));
270         return len - left;
271 }
272 
273 /* the caller has to hold the sock lock */
274 static int rds_tcp_read_sock(struct rds_connection *conn, gfp_t gfp)
275 {
276         struct rds_tcp_connection *tc = conn->c_transport_data;
277         struct socket *sock = tc->t_sock;
278         read_descriptor_t desc;
279         struct rds_tcp_desc_arg arg;
280 
281         /* It's like glib in the kernel! */
282         arg.conn = conn;
283         arg.gfp = gfp;
284         desc.arg.data = &arg;
285         desc.error = 0;
286         desc.count = 1; /* give more than one skb per call */
287 
288         tcp_read_sock(sock->sk, &desc, rds_tcp_data_recv);
289         rdsdebug("tcp_read_sock for tc %p gfp 0x%x returned %d\n", tc, gfp,
290                  desc.error);
291 
292         return desc.error;
293 }
294 
295 /*
296  * We hold the sock lock to serialize our rds_tcp_recv->tcp_read_sock from
297  * data_ready.
298  *
299  * if we fail to allocate we're in trouble.. blindly wait some time before
300  * trying again to see if the VM can free up something for us.
301  */
302 int rds_tcp_recv(struct rds_connection *conn)
303 {
304         struct rds_tcp_connection *tc = conn->c_transport_data;
305         struct socket *sock = tc->t_sock;
306         int ret = 0;
307 
308         rdsdebug("recv worker conn %p tc %p sock %p\n", conn, tc, sock);
309 
310         lock_sock(sock->sk);
311         ret = rds_tcp_read_sock(conn, GFP_KERNEL);
312         release_sock(sock->sk);
313 
314         return ret;
315 }
316 
317 void rds_tcp_data_ready(struct sock *sk)
318 {
319         void (*ready)(struct sock *sk);
320         struct rds_connection *conn;
321         struct rds_tcp_connection *tc;
322 
323         rdsdebug("data ready sk %p\n", sk);
324 
325         read_lock(&sk->sk_callback_lock);
326         conn = sk->sk_user_data;
327         if (!conn) { /* check for teardown race */
328                 ready = sk->sk_data_ready;
329                 goto out;
330         }
331 
332         tc = conn->c_transport_data;
333         ready = tc->t_orig_data_ready;
334         rds_tcp_stats_inc(s_tcp_data_ready_calls);
335 
336         if (rds_tcp_read_sock(conn, GFP_ATOMIC) == -ENOMEM)
337                 queue_delayed_work(rds_wq, &conn->c_recv_w, 0);
338 out:
339         read_unlock(&sk->sk_callback_lock);
340         ready(sk);
341 }
342 
343 int rds_tcp_recv_init(void)
344 {
345         rds_tcp_incoming_slab = kmem_cache_create("rds_tcp_incoming",
346                                         sizeof(struct rds_tcp_incoming),
347                                         0, 0, NULL);
348         if (!rds_tcp_incoming_slab)
349                 return -ENOMEM;
350         return 0;
351 }
352 
353 void rds_tcp_recv_exit(void)
354 {
355         kmem_cache_destroy(rds_tcp_incoming_slab);
356 }
357 

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