2 * Copyright (c) 1982, 1986, 1993
3 * The Regents of the University of California. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
13 * 3. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
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
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 $
34 * Error log buffer for kernel printf's.
37 #include <sys/param.h>
38 #include <sys/systm.h>
41 #include <sys/device.h>
43 #include <sys/vnode.h>
44 #include <sys/filio.h>
45 #include <sys/ttycom.h>
46 #include <sys/msgbuf.h>
47 #include <sys/signalvar.h>
48 #include <sys/kernel.h>
49 #include <sys/event.h>
50 #include <sys/filedesc.h>
51 #include <sys/sysctl.h>
52 #include <sys/thread2.h>
54 #define LOG_ASYNC 0x04
55 #define LOG_RDWAIT 0x08
57 static d_open_t logopen;
58 static d_close_t logclose;
59 static d_read_t logread;
60 static d_ioctl_t logioctl;
61 static d_kqfilter_t logkqfilter;
63 static void logtimeout(void *arg);
64 static void logfiltdetach(struct knote *kn);
65 static int logfiltread(struct knote *kn, long hint);
68 static struct dev_ops log_ops = {
74 .d_kqfilter = logkqfilter
77 static struct logsoftc {
78 int sc_state; /* see above for possibilities */
79 struct kqinfo sc_kqp; /* processes waiting on I/O */
80 struct sigio *sc_sigio; /* information for async I/O */
81 struct callout sc_callout; /* callout to wakeup syslog */
84 int log_open; /* also used in log() */
86 /* Times per second to check for a pending syslog wakeup. */
87 static int log_wakeups_per_second = 5;
88 SYSCTL_INT(_kern, OID_AUTO, log_wakeups_per_second, CTLFLAG_RW,
89 &log_wakeups_per_second, 0, "");
93 logopen(struct dev_open_args *ap)
95 struct proc *p = curproc;
101 callout_init_mp(&logsoftc.sc_callout);
102 fsetown(p->p_pid, &logsoftc.sc_sigio); /* signal process only */
103 callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
110 logclose(struct dev_close_args *ap)
113 callout_cancel(&logsoftc.sc_callout);
114 logsoftc.sc_state = 0;
115 funsetown(&logsoftc.sc_sigio);
121 logread(struct dev_read_args *ap)
123 struct uio *uio = ap->a_uio;
124 struct msgbuf *mbp = msgbufp;
134 while (mbp->msg_bufl == mbp->msg_bufx) {
136 if (ap->a_ioflag & IO_NDELAY) {
138 return (EWOULDBLOCK);
140 atomic_set_int(&logsoftc.sc_state, LOG_RDWAIT);
141 if ((error = tsleep((caddr_t)mbp, PCATCH, "klog", 0))) {
145 /* don't bother clearing LOG_RDWAIT */
152 while (uio->uio_resid > 0 && mbp->msg_bufl != mbp->msg_bufx) {
153 lindex = mbp->msg_bufl;
154 xindex = mbp->msg_bufx;
158 * Clean up if too much time has passed causing us to wrap
159 * the buffer. This will lose some data. If more than ~4GB
160 * then this will lose even more data.
163 if (n > mbp->msg_size - 1024) {
164 lindex = xindex - mbp->msg_size + 2048;
169 * Calculates contiguous bytes we can read in one loop.
171 lindex_modulo = lindex % mbp->msg_size;
172 n = mbp->msg_size - lindex_modulo;
173 if (n > xindex - lindex)
175 if ((size_t)n > uio->uio_resid)
176 n = (u_int)uio->uio_resid;
179 * Copy (n) bytes of data.
181 error = uiomove((caddr_t)msgbufp->msg_ptr + lindex_modulo,
185 mbp->msg_bufl = lindex + n;
190 static struct filterops logread_filtops =
191 { FILTEROP_ISFD, NULL, logfiltdetach, logfiltread };
194 logkqfilter(struct dev_kqfilter_args *ap)
196 struct knote *kn = ap->a_kn;
197 struct klist *klist = &logsoftc.sc_kqp.ki_note;
200 switch (kn->kn_filter) {
202 kn->kn_fop = &logread_filtops;
205 ap->a_result = EOPNOTSUPP;
209 knote_insert(klist, kn);
215 logfiltdetach(struct knote *kn)
217 struct klist *klist = &logsoftc.sc_kqp.ki_note;
219 knote_remove(klist, kn);
223 logfiltread(struct knote *kn, long hint)
228 if (msgbufp->msg_bufl != msgbufp->msg_bufx)
236 logtimeout(void *arg)
240 if (msgbuftrigger == 0) {
241 callout_reset(&logsoftc.sc_callout,
242 hz / log_wakeups_per_second, logtimeout, NULL);
246 KNOTE(&logsoftc.sc_kqp.ki_note, 0);
247 if ((logsoftc.sc_state & LOG_ASYNC) && logsoftc.sc_sigio != NULL)
248 pgsigio(logsoftc.sc_sigio, SIGIO, 0);
249 if (logsoftc.sc_state & LOG_RDWAIT) {
250 atomic_clear_int(&logsoftc.sc_state, LOG_RDWAIT);
251 wakeup((caddr_t)msgbufp);
253 callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
259 logioctl(struct dev_ioctl_args *ap)
261 struct msgbuf *mbp = msgbufp;
268 lindex = mbp->msg_bufl;
269 xindex = mbp->msg_bufx;
273 * Clean up if too much time has passed causing us to wrap
274 * the buffer. This will lose some data. If more than ~4GB
275 * then this will lose even more data.
278 if (n > mbp->msg_size - 1024) {
279 lindex = xindex - mbp->msg_size + 2048;
282 *(int *)ap->a_data = n;
286 if (*(int *)ap->a_data)
287 atomic_set_int(&logsoftc.sc_state, LOG_ASYNC);
289 atomic_clear_int(&logsoftc.sc_state, LOG_ASYNC);
293 return (fsetown(*(int *)ap->a_data, &logsoftc.sc_sigio));
296 *(int *)ap->a_data = fgetown(&logsoftc.sc_sigio);
299 /* This is deprecated, FIOSETOWN should be used instead. */
301 return (fsetown(-(*(int *)ap->a_data), &logsoftc.sc_sigio));
303 /* This is deprecated, FIOGETOWN should be used instead */
305 *(int *)ap->a_data = -fgetown(&logsoftc.sc_sigio);
315 log_drvinit(void *unused)
317 make_dev(&log_ops, 0, UID_ROOT, GID_WHEEL, 0600, "klog");
320 SYSINIT(logdev, SI_SUB_DRIVERS, SI_ORDER_MIDDLE + CDEV_MAJOR, log_drvinit,