Root/net/rds/tcp_recv.c

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
40static struct kmem_cache *rds_tcp_incoming_slab;
41
42void 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
50void 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 */
62int 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            size -= to_copy;
102            ret += to_copy;
103            skb_off += to_copy;
104            if (size == 0)
105                goto out;
106        }
107    }
108out:
109    return ret;
110}
111
112/*
113 * We have a series of skbs that have fragmented pieces of the congestion
114 * bitmap. They must add up to the exact size of the congestion bitmap. We
115 * use the skb helpers to copy those into the pages that make up the in-memory
116 * congestion bitmap for the remote address of this connection. We then tell
117 * the congestion core that the bitmap has been changed so that it can wake up
118 * sleepers.
119 *
120 * This is racing with sending paths which are using test_bit to see if the
121 * bitmap indicates that their recipient is congested.
122 */
123
124static void rds_tcp_cong_recv(struct rds_connection *conn,
125                  struct rds_tcp_incoming *tinc)
126{
127    struct sk_buff *skb;
128    unsigned int to_copy, skb_off;
129    unsigned int map_off;
130    unsigned int map_page;
131    struct rds_cong_map *map;
132    int ret;
133
134    /* catch completely corrupt packets */
135    if (be32_to_cpu(tinc->ti_inc.i_hdr.h_len) != RDS_CONG_MAP_BYTES)
136        return;
137
138    map_page = 0;
139    map_off = 0;
140    map = conn->c_fcong;
141
142    skb_queue_walk(&tinc->ti_skb_list, skb) {
143        skb_off = 0;
144        while (skb_off < skb->len) {
145            to_copy = min_t(unsigned int, PAGE_SIZE - map_off,
146                    skb->len - skb_off);
147
148            BUG_ON(map_page >= RDS_CONG_MAP_PAGES);
149
150            /* only returns 0 or -error */
151            ret = skb_copy_bits(skb, skb_off,
152                (void *)map->m_page_addrs[map_page] + map_off,
153                to_copy);
154            BUG_ON(ret != 0);
155
156            skb_off += to_copy;
157            map_off += to_copy;
158            if (map_off == PAGE_SIZE) {
159                map_off = 0;
160                map_page++;
161            }
162        }
163    }
164
165    rds_cong_map_updated(map, ~(u64) 0);
166}
167
168struct rds_tcp_desc_arg {
169    struct rds_connection *conn;
170    gfp_t gfp;
171    enum km_type km;
172};
173
174static 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 == NULL) {
193            tinc = kmem_cache_alloc(rds_tcp_incoming_slab,
194                            arg->gfp);
195            if (tinc == NULL) {
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 == NULL) {
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, arg->km);
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    }
266out:
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 */
274int rds_tcp_read_sock(struct rds_connection *conn, gfp_t gfp, enum km_type km)
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    arg.km = km;
285    desc.arg.data = &arg;
286    desc.error = 0;
287    desc.count = 1; /* give more than one skb per call */
288
289    tcp_read_sock(sock->sk, &desc, rds_tcp_data_recv);
290    rdsdebug("tcp_read_sock for tc %p gfp 0x%x returned %d\n", tc, gfp,
291         desc.error);
292
293    return desc.error;
294}
295
296/*
297 * We hold the sock lock to serialize our rds_tcp_recv->tcp_read_sock from
298 * data_ready.
299 *
300 * if we fail to allocate we're in trouble.. blindly wait some time before
301 * trying again to see if the VM can free up something for us.
302 */
303int rds_tcp_recv(struct rds_connection *conn)
304{
305    struct rds_tcp_connection *tc = conn->c_transport_data;
306    struct socket *sock = tc->t_sock;
307    int ret = 0;
308
309    rdsdebug("recv worker conn %p tc %p sock %p\n", conn, tc, sock);
310
311    lock_sock(sock->sk);
312    ret = rds_tcp_read_sock(conn, GFP_KERNEL, KM_USER0);
313    release_sock(sock->sk);
314
315    return ret;
316}
317
318void rds_tcp_data_ready(struct sock *sk, int bytes)
319{
320    void (*ready)(struct sock *sk, int bytes);
321    struct rds_connection *conn;
322    struct rds_tcp_connection *tc;
323
324    rdsdebug("data ready sk %p bytes %d\n", sk, bytes);
325
326    read_lock(&sk->sk_callback_lock);
327    conn = sk->sk_user_data;
328    if (conn == NULL) { /* check for teardown race */
329        ready = sk->sk_data_ready;
330        goto out;
331    }
332
333    tc = conn->c_transport_data;
334    ready = tc->t_orig_data_ready;
335    rds_tcp_stats_inc(s_tcp_data_ready_calls);
336
337    if (rds_tcp_read_sock(conn, GFP_ATOMIC, KM_SOFTIRQ0) == -ENOMEM)
338        queue_delayed_work(rds_wq, &conn->c_recv_w, 0);
339out:
340    read_unlock(&sk->sk_callback_lock);
341    ready(sk, bytes);
342}
343
344int __init rds_tcp_recv_init(void)
345{
346    rds_tcp_incoming_slab = kmem_cache_create("rds_tcp_incoming",
347                    sizeof(struct rds_tcp_incoming),
348                    0, 0, NULL);
349    if (rds_tcp_incoming_slab == NULL)
350        return -ENOMEM;
351    return 0;
352}
353
354void rds_tcp_recv_exit(void)
355{
356    kmem_cache_destroy(rds_tcp_incoming_slab);
357}
358

Archive Download this file



interactive