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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>
40 #include <sys/device.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>
48 #include <sys/event.h>
49 #include <sys/filedesc.h>
50 #include <sys/sysctl.h>
51 #include <sys/thread2.h>
53 #define LOG_ASYNC 0x04
54 #define LOG_RDWAIT 0x08
56 static d_open_t logopen;
57 static d_close_t logclose;
58 static d_read_t logread;
59 static d_ioctl_t logioctl;
60 static d_kqfilter_t logkqfilter;
62 static void logtimeout(void *arg);
63 static void logfiltdetach(struct knote *kn);
64 static int logfiltread(struct knote *kn, long hint);
67 static struct dev_ops log_ops = {
73 .d_kqfilter = logkqfilter
76 static struct logsoftc {
77 int sc_state; /* see above for possibilities */
78 struct kqinfo sc_kqp; /* processes waiting on I/O */
79 struct sigio *sc_sigio; /* information for async I/O */
80 struct callout sc_callout; /* callout to wakeup syslog */
83 int log_open; /* also used in log() */
85 /* Times per second to check for a pending syslog wakeup. */
86 static int log_wakeups_per_second = 5;
87 SYSCTL_INT(_kern, OID_AUTO, log_wakeups_per_second, CTLFLAG_RW,
88 &log_wakeups_per_second, 0, "");
92 logopen(struct dev_open_args *ap)
94 struct proc *p = curproc;
100 callout_init_mp(&logsoftc.sc_callout);
101 fsetown(p->p_pid, &logsoftc.sc_sigio); /* signal process only */
102 callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
109 logclose(struct dev_close_args *ap)
112 callout_stop_sync(&logsoftc.sc_callout);
113 logsoftc.sc_state = 0;
114 funsetown(&logsoftc.sc_sigio);
120 logread(struct dev_read_args *ap)
122 struct uio *uio = ap->a_uio;
123 struct msgbuf *mbp = msgbufp;
133 while (mbp->msg_bufl == mbp->msg_bufx) {
135 if (ap->a_ioflag & IO_NDELAY) {
137 return (EWOULDBLOCK);
139 atomic_set_int(&logsoftc.sc_state, LOG_RDWAIT);
140 if ((error = tsleep((caddr_t)mbp, PCATCH, "klog", 0))) {
144 /* don't bother clearing LOG_RDWAIT */
151 while (uio->uio_resid > 0 && mbp->msg_bufl != mbp->msg_bufx) {
152 lindex = mbp->msg_bufl;
153 xindex = mbp->msg_bufx;
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.
162 if (n > mbp->msg_size - 1024) {
163 lindex = xindex - mbp->msg_size + 2048;
168 * Calculates contiguous bytes we can read in one loop.
170 lindex_modulo = lindex % mbp->msg_size;
171 n = mbp->msg_size - lindex_modulo;
172 if (n > xindex - lindex)
174 if ((size_t)n > uio->uio_resid)
175 n = (u_int)uio->uio_resid;
178 * Copy (n) bytes of data.
180 error = uiomove((caddr_t)msgbufp->msg_ptr + lindex_modulo,
184 mbp->msg_bufl = lindex + n;
189 static struct filterops logread_filtops =
190 { FILTEROP_ISFD, NULL, logfiltdetach, logfiltread };
193 logkqfilter(struct dev_kqfilter_args *ap)
195 struct knote *kn = ap->a_kn;
196 struct klist *klist = &logsoftc.sc_kqp.ki_note;
199 switch (kn->kn_filter) {
201 kn->kn_fop = &logread_filtops;
204 ap->a_result = EOPNOTSUPP;
208 knote_insert(klist, kn);
214 logfiltdetach(struct knote *kn)
216 struct klist *klist = &logsoftc.sc_kqp.ki_note;
218 knote_remove(klist, kn);
222 logfiltread(struct knote *kn, long hint)
227 if (msgbufp->msg_bufl != msgbufp->msg_bufx)
235 logtimeout(void *arg)
239 if (msgbuftrigger == 0) {
240 callout_reset(&logsoftc.sc_callout,
241 hz / log_wakeups_per_second, logtimeout, NULL);
245 KNOTE(&logsoftc.sc_kqp.ki_note, 0);
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) {
249 atomic_clear_int(&logsoftc.sc_state, LOG_RDWAIT);
250 wakeup((caddr_t)msgbufp);
252 callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
258 logioctl(struct dev_ioctl_args *ap)
260 struct msgbuf *mbp = msgbufp;
267 lindex = mbp->msg_bufl;
268 xindex = mbp->msg_bufx;
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.
277 if (n > mbp->msg_size - 1024) {
278 lindex = xindex - mbp->msg_size + 2048;
281 *(int *)ap->a_data = n;
285 if (*(int *)ap->a_data)
286 atomic_set_int(&logsoftc.sc_state, LOG_ASYNC);
288 atomic_clear_int(&logsoftc.sc_state, LOG_ASYNC);
292 return (fsetown(*(int *)ap->a_data, &logsoftc.sc_sigio));
295 *(int *)ap->a_data = fgetown(&logsoftc.sc_sigio);
298 /* This is deprecated, FIOSETOWN should be used instead. */
300 return (fsetown(-(*(int *)ap->a_data), &logsoftc.sc_sigio));
302 /* This is deprecated, FIOGETOWN should be used instead */
304 *(int *)ap->a_data = -fgetown(&logsoftc.sc_sigio);
314 log_drvinit(void *unused)
316 make_dev(&log_ops, 0, UID_ROOT, GID_WHEEL, 0600, "klog");
319 SYSINIT(logdev, SI_SUB_DRIVERS, SI_ORDER_MIDDLE + CDEV_MAJOR, log_drvinit,