kernel - Refactor the kernel message buffer code
[dragonfly.git] / sys / kern / subr_log.c
CommitLineData
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1/*
2 * Copyright (c) 1982, 1986, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
dc71b7ab 13 * 3. Neither the name of the University nor the names of its contributors
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14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * @(#)subr_log.c 8.1 (Berkeley) 6/10/93
30 * $FreeBSD: src/sys/kern/subr_log.c,v 1.39.2.2 2001/06/02 08:11:25 phk Exp $
31 */
32
33/*
34 * Error log buffer for kernel printf's.
35 */
36
37#include <sys/param.h>
38#include <sys/systm.h>
39#include <sys/conf.h>
fef8985e 40#include <sys/device.h>
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41#include <sys/proc.h>
42#include <sys/vnode.h>
43#include <sys/filio.h>
44#include <sys/ttycom.h>
45#include <sys/msgbuf.h>
46#include <sys/signalvar.h>
47#include <sys/kernel.h>
fef8f01a 48#include <sys/event.h>
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49#include <sys/filedesc.h>
50#include <sys/sysctl.h>
e43a034f 51#include <sys/thread2.h>
984263bc 52
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53#define LOG_ASYNC 0x04
54#define LOG_RDWAIT 0x08
55
56static d_open_t logopen;
57static d_close_t logclose;
58static d_read_t logread;
59static d_ioctl_t logioctl;
fef8f01a 60static d_kqfilter_t logkqfilter;
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61
62static void logtimeout(void *arg);
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63static void logfiltdetach(struct knote *kn);
64static int logfiltread(struct knote *kn, long hint);
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65
66#define CDEV_MAJOR 7
fef8985e 67static struct dev_ops log_ops = {
88abd8b5 68 { "log", 0, 0 },
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69 .d_open = logopen,
70 .d_close = logclose,
71 .d_read = logread,
72 .d_ioctl = logioctl,
fef8f01a 73 .d_kqfilter = logkqfilter
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74};
75
76static struct logsoftc {
77 int sc_state; /* see above for possibilities */
5b22f1a7 78 struct kqinfo sc_kqp; /* processes waiting on I/O */
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79 struct sigio *sc_sigio; /* information for async I/O */
80 struct callout sc_callout; /* callout to wakeup syslog */
81} logsoftc;
82
83int log_open; /* also used in log() */
84
85/* Times per second to check for a pending syslog wakeup. */
86static int log_wakeups_per_second = 5;
87SYSCTL_INT(_kern, OID_AUTO, log_wakeups_per_second, CTLFLAG_RW,
88 &log_wakeups_per_second, 0, "");
89
90/*ARGSUSED*/
91static int
fef8985e 92logopen(struct dev_open_args *ap)
984263bc 93{
fef8985e 94 struct proc *p = curproc;
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95
96 KKASSERT(p != NULL);
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97 if (log_open)
98 return (EBUSY);
99 log_open = 1;
bf0ecf68 100 callout_init_mp(&logsoftc.sc_callout);
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101 fsetown(p->p_pid, &logsoftc.sc_sigio); /* signal process only */
102 callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
bf0ecf68 103 logtimeout, NULL);
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104 return (0);
105}
106
107/*ARGSUSED*/
108static int
fef8985e 109logclose(struct dev_close_args *ap)
984263bc 110{
984263bc 111 log_open = 0;
5608ef17 112 callout_stop_sync(&logsoftc.sc_callout);
984263bc 113 logsoftc.sc_state = 0;
58c2553a 114 funsetown(&logsoftc.sc_sigio);
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115 return (0);
116}
117
118/*ARGSUSED*/
119static int
fef8985e 120logread(struct dev_read_args *ap)
984263bc 121{
fef8985e 122 struct uio *uio = ap->a_uio;
984263bc 123 struct msgbuf *mbp = msgbufp;
984263bc 124 int error = 0;
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125 u_int lindex;
126 u_int xindex;
127 u_int lindex_modulo;
128 u_int n;
129
130 /*
131 * Handle blocking
132 */
133 while (mbp->msg_bufl == mbp->msg_bufx) {
134 crit_enter();
fef8985e 135 if (ap->a_ioflag & IO_NDELAY) {
e43a034f 136 crit_exit();
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137 return (EWOULDBLOCK);
138 }
5608ef17 139 atomic_set_int(&logsoftc.sc_state, LOG_RDWAIT);
377d4740 140 if ((error = tsleep((caddr_t)mbp, PCATCH, "klog", 0))) {
e43a034f 141 crit_exit();
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142 return (error);
143 }
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144 /* don't bother clearing LOG_RDWAIT */
145 crit_exit();
984263bc 146 }
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147
148 /*
149 * Loop reading data
150 */
151 while (uio->uio_resid > 0 && mbp->msg_bufl != mbp->msg_bufx) {
152 lindex = mbp->msg_bufl;
153 xindex = mbp->msg_bufx;
154 cpu_ccfence();
155
156 /*
157 * Clean up if too much time has passed causing us to wrap
158 * the buffer. This will lose some data. If more than ~4GB
159 * then this will lose even more data.
160 */
161 n = xindex - lindex;
162 if (n > mbp->msg_size - 1024) {
163 lindex = xindex - mbp->msg_size + 2048;
164 n = xindex - lindex;
165 }
166
167 /*
168 * Calculates contiguous bytes we can read in one loop.
169 */
170 lindex_modulo = lindex % mbp->msg_size;
171 n = mbp->msg_size - lindex_modulo;
172 if (n > xindex - lindex)
173 n = xindex - lindex;
174 if ((size_t)n > uio->uio_resid)
175 n = (u_int)uio->uio_resid;
176
177 /*
178 * Copy (n) bytes of data.
179 */
180 error = uiomove((caddr_t)msgbufp->msg_ptr + lindex_modulo,
181 (size_t)n, uio);
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182 if (error)
183 break;
5608ef17 184 mbp->msg_bufl = lindex + n;
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185 }
186 return (error);
187}
188
fef8f01a 189static struct filterops logread_filtops =
4c91dbc9 190 { FILTEROP_ISFD, NULL, logfiltdetach, logfiltread };
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191
192static int
193logkqfilter(struct dev_kqfilter_args *ap)
194{
195 struct knote *kn = ap->a_kn;
5b22f1a7 196 struct klist *klist = &logsoftc.sc_kqp.ki_note;
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197
198 ap->a_result = 0;
199 switch (kn->kn_filter) {
200 case EVFILT_READ:
201 kn->kn_fop = &logread_filtops;
202 break;
203 default:
b287d649 204 ap->a_result = EOPNOTSUPP;
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205 return (0);
206 }
207
5b22f1a7 208 knote_insert(klist, kn);
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209
210 return (0);
211}
212
213static void
214logfiltdetach(struct knote *kn)
215{
5b22f1a7 216 struct klist *klist = &logsoftc.sc_kqp.ki_note;
fef8f01a 217
5b22f1a7 218 knote_remove(klist, kn);
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219}
220
221static int
222logfiltread(struct knote *kn, long hint)
223{
224 int ret = 0;
225
226 crit_enter();
5608ef17 227 if (msgbufp->msg_bufl != msgbufp->msg_bufx)
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228 ret = 1;
229 crit_exit();
230
231 return (ret);
232}
233
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234static void
235logtimeout(void *arg)
236{
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237 if (!log_open)
238 return;
239 if (msgbuftrigger == 0) {
240 callout_reset(&logsoftc.sc_callout,
bf0ecf68 241 hz / log_wakeups_per_second, logtimeout, NULL);
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242 return;
243 }
244 msgbuftrigger = 0;
5b22f1a7 245 KNOTE(&logsoftc.sc_kqp.ki_note, 0);
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246 if ((logsoftc.sc_state & LOG_ASYNC) && logsoftc.sc_sigio != NULL)
247 pgsigio(logsoftc.sc_sigio, SIGIO, 0);
248 if (logsoftc.sc_state & LOG_RDWAIT) {
5608ef17 249 atomic_clear_int(&logsoftc.sc_state, LOG_RDWAIT);
984263bc 250 wakeup((caddr_t)msgbufp);
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251 }
252 callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
bf0ecf68 253 logtimeout, NULL);
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254}
255
256/*ARGSUSED*/
257static int
fef8985e 258logioctl(struct dev_ioctl_args *ap)
984263bc 259{
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260 struct msgbuf *mbp = msgbufp;
261 u_int lindex;
262 u_int xindex;
263 u_int n;
984263bc 264
fef8985e 265 switch (ap->a_cmd) {
984263bc 266 case FIONREAD:
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267 lindex = mbp->msg_bufl;
268 xindex = mbp->msg_bufx;
269 cpu_ccfence();
270
271 /*
272 * Clean up if too much time has passed causing us to wrap
273 * the buffer. This will lose some data. If more than ~4GB
274 * then this will lose even more data.
275 */
276 n = xindex - lindex;
277 if (n > mbp->msg_size - 1024) {
278 lindex = xindex - mbp->msg_size + 2048;
279 n = xindex - lindex;
280 }
281 *(int *)ap->a_data = n;
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282 break;
283
984263bc 284 case FIOASYNC:
fef8985e 285 if (*(int *)ap->a_data)
5608ef17 286 atomic_set_int(&logsoftc.sc_state, LOG_ASYNC);
984263bc 287 else
5608ef17 288 atomic_clear_int(&logsoftc.sc_state, LOG_ASYNC);
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289 break;
290
291 case FIOSETOWN:
fef8985e 292 return (fsetown(*(int *)ap->a_data, &logsoftc.sc_sigio));
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293
294 case FIOGETOWN:
b5c4d81f 295 *(int *)ap->a_data = fgetown(&logsoftc.sc_sigio);
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296 break;
297
298 /* This is deprecated, FIOSETOWN should be used instead. */
299 case TIOCSPGRP:
fef8985e 300 return (fsetown(-(*(int *)ap->a_data), &logsoftc.sc_sigio));
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301
302 /* This is deprecated, FIOGETOWN should be used instead */
303 case TIOCGPGRP:
b5c4d81f 304 *(int *)ap->a_data = -fgetown(&logsoftc.sc_sigio);
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305 break;
306
307 default:
308 return (ENOTTY);
309 }
310 return (0);
311}
312
313static void
314log_drvinit(void *unused)
315{
fef8985e 316 make_dev(&log_ops, 0, UID_ROOT, GID_WHEEL, 0600, "klog");
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317}
318
319SYSINIT(logdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,log_drvinit,NULL)