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33 * @(#)subr_log.c 8.1 (Berkeley) 6/10/93
34 * $FreeBSD: src/sys/kern/subr_log.c,v 1.39.2.2 2001/06/02 08:11:25 phk Exp $
35 * $DragonFly: src/sys/kern/subr_log.c,v 1.10 2006/07/28 02:17:40 dillon Exp $
39 * Error log buffer for kernel printf's.
42 #include <sys/param.h>
43 #include <sys/systm.h>
45 #include <sys/device.h>
47 #include <sys/vnode.h>
48 #include <sys/filio.h>
49 #include <sys/ttycom.h>
50 #include <sys/msgbuf.h>
51 #include <sys/signalvar.h>
52 #include <sys/kernel.h>
53 #include <sys/event.h>
54 #include <sys/filedesc.h>
55 #include <sys/sysctl.h>
56 #include <sys/thread2.h>
58 #define LOG_ASYNC 0x04
59 #define LOG_RDWAIT 0x08
61 static d_open_t logopen;
62 static d_close_t logclose;
63 static d_read_t logread;
64 static d_ioctl_t logioctl;
65 static d_kqfilter_t logkqfilter;
67 static void logtimeout(void *arg);
68 static void logfiltdetach(struct knote *kn);
69 static int logfiltread(struct knote *kn, long hint);
72 static struct dev_ops log_ops = {
73 { "log", CDEV_MAJOR, D_KQFILTER },
78 .d_kqfilter = logkqfilter
81 static struct logsoftc {
82 int sc_state; /* see above for possibilities */
83 struct selinfo sc_selp; /* process waiting on select call */
84 struct sigio *sc_sigio; /* information for async I/O */
85 struct callout sc_callout; /* callout to wakeup syslog */
88 int log_open; /* also used in log() */
90 /* Times per second to check for a pending syslog wakeup. */
91 static int log_wakeups_per_second = 5;
92 SYSCTL_INT(_kern, OID_AUTO, log_wakeups_per_second, CTLFLAG_RW,
93 &log_wakeups_per_second, 0, "");
97 logopen(struct dev_open_args *ap)
99 struct proc *p = curproc;
105 callout_init(&logsoftc.sc_callout);
106 fsetown(p->p_pid, &logsoftc.sc_sigio); /* signal process only */
107 callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
114 logclose(struct dev_close_args *ap)
117 callout_stop(&logsoftc.sc_callout);
118 logsoftc.sc_state = 0;
119 funsetown(logsoftc.sc_sigio);
125 logread(struct dev_read_args *ap)
127 struct uio *uio = ap->a_uio;
128 struct msgbuf *mbp = msgbufp;
133 while (mbp->msg_bufr == mbp->msg_bufx) {
134 if (ap->a_ioflag & IO_NDELAY) {
136 return (EWOULDBLOCK);
138 logsoftc.sc_state |= LOG_RDWAIT;
139 if ((error = tsleep((caddr_t)mbp, PCATCH, "klog", 0))) {
145 logsoftc.sc_state &= ~LOG_RDWAIT;
147 while (uio->uio_resid > 0) {
148 l = (long)mbp->msg_bufx - (long)mbp->msg_bufr;
150 l = mbp->msg_size - mbp->msg_bufr;
151 l = (long)szmin(l, uio->uio_resid);
154 error = uiomove((caddr_t)msgbufp->msg_ptr + mbp->msg_bufr,
159 if (mbp->msg_bufr >= mbp->msg_size)
165 static struct filterops logread_filtops =
166 { 1, NULL, logfiltdetach, logfiltread };
169 logkqfilter(struct dev_kqfilter_args *ap)
171 struct knote *kn = ap->a_kn;
172 struct klist *klist = &logsoftc.sc_selp.si_note;
175 switch (kn->kn_filter) {
177 kn->kn_fop = &logread_filtops;
180 ap->a_result = EOPNOTSUPP;
185 SLIST_INSERT_HEAD(klist, kn, kn_selnext);
192 logfiltdetach(struct knote *kn)
194 struct klist *klist = &logsoftc.sc_selp.si_note;
197 SLIST_REMOVE(klist, kn, knote, kn_selnext);
202 logfiltread(struct knote *kn, long hint)
207 if (msgbufp->msg_bufr != msgbufp->msg_bufx)
215 logtimeout(void *arg)
220 if (msgbuftrigger == 0) {
221 callout_reset(&logsoftc.sc_callout,
222 hz / log_wakeups_per_second, logtimeout, NULL);
226 selwakeup(&logsoftc.sc_selp);
227 if ((logsoftc.sc_state & LOG_ASYNC) && logsoftc.sc_sigio != NULL)
228 pgsigio(logsoftc.sc_sigio, SIGIO, 0);
229 if (logsoftc.sc_state & LOG_RDWAIT) {
230 wakeup((caddr_t)msgbufp);
231 logsoftc.sc_state &= ~LOG_RDWAIT;
233 callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
239 logioctl(struct dev_ioctl_args *ap)
245 /* return number of characters immediately available */
247 l = msgbufp->msg_bufx - msgbufp->msg_bufr;
250 l += msgbufp->msg_size;
251 *(int *)ap->a_data = l;
255 if (*(int *)ap->a_data)
256 logsoftc.sc_state |= LOG_ASYNC;
258 logsoftc.sc_state &= ~LOG_ASYNC;
262 return (fsetown(*(int *)ap->a_data, &logsoftc.sc_sigio));
265 *(int *)ap->a_data = fgetown(logsoftc.sc_sigio);
268 /* This is deprecated, FIOSETOWN should be used instead. */
270 return (fsetown(-(*(int *)ap->a_data), &logsoftc.sc_sigio));
272 /* This is deprecated, FIOGETOWN should be used instead */
274 *(int *)ap->a_data = -fgetown(logsoftc.sc_sigio);
284 log_drvinit(void *unused)
286 make_dev(&log_ops, 0, UID_ROOT, GID_WHEEL, 0600, "klog");
289 SYSINIT(logdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,log_drvinit,NULL)