FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_sfbuf.c
1 /*-
2 * Copyright (c) 2014 Gleb Smirnoff <glebius@FreeBSD.org>
3 * Copyright (c) 2003, 2005 Alan L. Cox <alc@cs.rice.edu>
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28 #include <sys/cdefs.h>
29 __FBSDID("$FreeBSD: releng/11.0/sys/kern/subr_sfbuf.c 269813 2014-08-11 15:06:07Z glebius $");
30
31 #include <sys/param.h>
32 #include <sys/kernel.h>
33 #include <sys/lock.h>
34 #include <sys/malloc.h>
35 #include <sys/mutex.h>
36 #include <sys/sf_buf.h>
37 #include <sys/smp.h>
38 #include <sys/sysctl.h>
39
40 #include <vm/vm.h>
41 #include <vm/vm_extern.h>
42 #include <vm/vm_page.h>
43
44 #ifndef NSFBUFS
45 #define NSFBUFS (512 + maxusers * 16)
46 #endif
47
48 static int nsfbufs;
49 static int nsfbufspeak;
50 static int nsfbufsused;
51
52 SYSCTL_INT(_kern_ipc, OID_AUTO, nsfbufs, CTLFLAG_RDTUN, &nsfbufs, 0,
53 "Maximum number of sendfile(2) sf_bufs available");
54 SYSCTL_INT(_kern_ipc, OID_AUTO, nsfbufspeak, CTLFLAG_RD, &nsfbufspeak, 0,
55 "Number of sendfile(2) sf_bufs at peak usage");
56 SYSCTL_INT(_kern_ipc, OID_AUTO, nsfbufsused, CTLFLAG_RD, &nsfbufsused, 0,
57 "Number of sendfile(2) sf_bufs in use");
58
59 static void sf_buf_init(void *arg);
60 SYSINIT(sock_sf, SI_SUB_MBUF, SI_ORDER_ANY, sf_buf_init, NULL);
61
62 LIST_HEAD(sf_head, sf_buf);
63
64 /*
65 * A hash table of active sendfile(2) buffers
66 */
67 static struct sf_head *sf_buf_active;
68 static u_long sf_buf_hashmask;
69
70 #define SF_BUF_HASH(m) (((m) - vm_page_array) & sf_buf_hashmask)
71
72 static TAILQ_HEAD(, sf_buf) sf_buf_freelist;
73 static u_int sf_buf_alloc_want;
74
75 /*
76 * A lock used to synchronize access to the hash table and free list
77 */
78 static struct mtx sf_buf_lock;
79
80 /*
81 * Allocate a pool of sf_bufs (sendfile(2) or "super-fast" if you prefer. :-))
82 */
83 static void
84 sf_buf_init(void *arg)
85 {
86 struct sf_buf *sf_bufs;
87 vm_offset_t sf_base;
88 int i;
89
90 #ifdef SFBUF_OPTIONAL_DIRECT_MAP
91 if (SFBUF_OPTIONAL_DIRECT_MAP)
92 return;
93 #endif
94
95 nsfbufs = NSFBUFS;
96 TUNABLE_INT_FETCH("kern.ipc.nsfbufs", &nsfbufs);
97
98 sf_buf_active = hashinit(nsfbufs, M_TEMP, &sf_buf_hashmask);
99 TAILQ_INIT(&sf_buf_freelist);
100 sf_base = kva_alloc(nsfbufs * PAGE_SIZE);
101 sf_bufs = malloc(nsfbufs * sizeof(struct sf_buf), M_TEMP,
102 M_WAITOK | M_ZERO);
103 for (i = 0; i < nsfbufs; i++) {
104 sf_bufs[i].kva = sf_base + i * PAGE_SIZE;
105 TAILQ_INSERT_TAIL(&sf_buf_freelist, &sf_bufs[i], free_entry);
106 }
107 sf_buf_alloc_want = 0;
108 mtx_init(&sf_buf_lock, "sf_buf", NULL, MTX_DEF);
109 }
110
111 /*
112 * Get an sf_buf from the freelist. May block if none are available.
113 */
114 struct sf_buf *
115 sf_buf_alloc(struct vm_page *m, int flags)
116 {
117 struct sf_head *hash_list;
118 struct sf_buf *sf;
119 int error;
120
121 #ifdef SFBUF_OPTIONAL_DIRECT_MAP
122 if (SFBUF_OPTIONAL_DIRECT_MAP)
123 return ((struct sf_buf *)m);
124 #endif
125
126 KASSERT(curthread->td_pinned > 0 || (flags & SFB_CPUPRIVATE) == 0,
127 ("sf_buf_alloc(SFB_CPUPRIVATE): curthread not pinned"));
128 hash_list = &sf_buf_active[SF_BUF_HASH(m)];
129 mtx_lock(&sf_buf_lock);
130 LIST_FOREACH(sf, hash_list, list_entry) {
131 if (sf->m == m) {
132 sf->ref_count++;
133 if (sf->ref_count == 1) {
134 TAILQ_REMOVE(&sf_buf_freelist, sf, free_entry);
135 nsfbufsused++;
136 nsfbufspeak = imax(nsfbufspeak, nsfbufsused);
137 }
138 #if defined(SMP) && defined(SFBUF_CPUSET)
139 sf_buf_shootdown(sf, flags);
140 #endif
141 goto done;
142 }
143 }
144 while ((sf = TAILQ_FIRST(&sf_buf_freelist)) == NULL) {
145 if (flags & SFB_NOWAIT)
146 goto done;
147 sf_buf_alloc_want++;
148 SFSTAT_INC(sf_allocwait);
149 error = msleep(&sf_buf_freelist, &sf_buf_lock,
150 (flags & SFB_CATCH) ? PCATCH | PVM : PVM, "sfbufa", 0);
151 sf_buf_alloc_want--;
152
153 /*
154 * If we got a signal, don't risk going back to sleep.
155 */
156 if (error)
157 goto done;
158 }
159 TAILQ_REMOVE(&sf_buf_freelist, sf, free_entry);
160 if (sf->m != NULL)
161 LIST_REMOVE(sf, list_entry);
162 LIST_INSERT_HEAD(hash_list, sf, list_entry);
163 sf->ref_count = 1;
164 sf->m = m;
165 nsfbufsused++;
166 nsfbufspeak = imax(nsfbufspeak, nsfbufsused);
167 sf_buf_map(sf, flags);
168 done:
169 mtx_unlock(&sf_buf_lock);
170 return (sf);
171 }
172
173 /*
174 * Remove a reference from the given sf_buf, adding it to the free
175 * list when its reference count reaches zero. A freed sf_buf still,
176 * however, retains its virtual-to-physical mapping until it is
177 * recycled or reactivated by sf_buf_alloc(9).
178 */
179 void
180 sf_buf_free(struct sf_buf *sf)
181 {
182
183 #ifdef SFBUF_OPTIONAL_DIRECT_MAP
184 if (SFBUF_OPTIONAL_DIRECT_MAP)
185 return;
186 #endif
187
188 mtx_lock(&sf_buf_lock);
189 sf->ref_count--;
190 if (sf->ref_count == 0) {
191 TAILQ_INSERT_TAIL(&sf_buf_freelist, sf, free_entry);
192 nsfbufsused--;
193 if (sf_buf_unmap(sf)) {
194 sf->m = NULL;
195 LIST_REMOVE(sf, list_entry);
196 }
197 if (sf_buf_alloc_want > 0)
198 wakeup(&sf_buf_freelist);
199 }
200 mtx_unlock(&sf_buf_lock);
201 }
202
203 void
204 sf_buf_ref(struct sf_buf *sf)
205 {
206
207 #ifdef SFBUF_OPTIONAL_DIRECT_MAP
208 if (SFBUF_OPTIONAL_DIRECT_MAP)
209 return;
210 #endif
211
212 mtx_lock(&sf_buf_lock);
213 KASSERT(sf->ref_count > 0, ("%s: sf %p not allocated", __func__, sf));
214 sf->ref_count++;
215 mtx_unlock(&sf_buf_lock);
216 }
217
218 #ifdef SFBUF_PROCESS_PAGE
219 /*
220 * Run callback function on sf_buf that holds a certain page.
221 */
222 boolean_t
223 sf_buf_process_page(vm_page_t m, void (*cb)(struct sf_buf *))
224 {
225 struct sf_head *hash_list;
226 struct sf_buf *sf;
227
228 hash_list = &sf_buf_active[SF_BUF_HASH(m)];
229 mtx_lock(&sf_buf_lock);
230 LIST_FOREACH(sf, hash_list, list_entry) {
231 if (sf->m == m) {
232 cb(sf);
233 mtx_unlock(&sf_buf_lock);
234 return (TRUE);
235 }
236 }
237 mtx_unlock(&sf_buf_lock);
238 return (FALSE);
239 }
240 #endif /* SFBUF_PROCESS_PAGE */
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