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29 * @(#)subr_log.c 8.1 (Berkeley) 6/10/93
33 * Error log buffer for kernel printf's.
36 #include <sys/cdefs.h>
37 __FBSDID("$FreeBSD$");
39 #include <sys/param.h>
40 #include <sys/systm.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>
50 #include <sys/filedesc.h>
51 #include <sys/sysctl.h>
53 #define LOG_RDPRI (PZERO + 1)
55 #define LOG_ASYNC 0x04
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_poll_t logpoll;
62 static d_kqfilter_t logkqfilter;
64 static void logtimeout(void *arg);
66 static struct cdevsw log_cdevsw = {
67 .d_version = D_VERSION,
73 .d_kqfilter = logkqfilter,
77 static int logkqread(struct knote *note, long hint);
78 static void logkqdetach(struct knote *note);
80 static struct filterops log_read_filterops = {
83 .f_detach = logkqdetach,
87 static struct logsoftc {
88 int sc_state; /* see above for possibilities */
89 struct selinfo sc_selp; /* process waiting on select call */
90 struct sigio *sc_sigio; /* information for async I/O */
91 struct callout sc_callout; /* callout to wakeup syslog */
94 int log_open; /* also used in log() */
95 static struct cv log_wakeup;
96 struct mtx msgbuf_lock;
97 MTX_SYSINIT(msgbuf_lock, &msgbuf_lock, "msgbuf lock", MTX_DEF);
99 /* Times per second to check for a pending syslog wakeup. */
100 static int log_wakeups_per_second = 5;
101 SYSCTL_INT(_kern, OID_AUTO, log_wakeups_per_second, CTLFLAG_RW,
102 &log_wakeups_per_second, 0, "");
106 logopen(struct cdev *dev, int flags, int mode, struct thread *td)
109 if (log_wakeups_per_second < 1) {
110 printf("syslog wakeup is less than one. Adjusting to 1.\n");
111 log_wakeups_per_second = 1;
114 mtx_lock(&msgbuf_lock);
116 mtx_unlock(&msgbuf_lock);
120 callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
122 mtx_unlock(&msgbuf_lock);
124 fsetown(td->td_proc->p_pid, &logsoftc.sc_sigio); /* signal process only */
130 logclose(struct cdev *dev, int flag, int mode, struct thread *td)
133 funsetown(&logsoftc.sc_sigio);
135 mtx_lock(&msgbuf_lock);
136 callout_stop(&logsoftc.sc_callout);
137 logsoftc.sc_state = 0;
139 mtx_unlock(&msgbuf_lock);
146 logread(struct cdev *dev, struct uio *uio, int flag)
149 struct msgbuf *mbp = msgbufp;
152 mtx_lock(&msgbuf_lock);
153 while (msgbuf_getcount(mbp) == 0) {
154 if (flag & IO_NDELAY) {
155 mtx_unlock(&msgbuf_lock);
156 return (EWOULDBLOCK);
158 if ((error = cv_wait_sig(&log_wakeup, &msgbuf_lock)) != 0) {
159 mtx_unlock(&msgbuf_lock);
164 while (uio->uio_resid > 0) {
165 l = imin(sizeof(buf), uio->uio_resid);
166 l = msgbuf_getbytes(mbp, buf, l);
169 mtx_unlock(&msgbuf_lock);
170 error = uiomove(buf, l, uio);
171 if (error || uio->uio_resid == 0)
173 mtx_lock(&msgbuf_lock);
175 mtx_unlock(&msgbuf_lock);
181 logpoll(struct cdev *dev, int events, struct thread *td)
185 if (events & (POLLIN | POLLRDNORM)) {
186 mtx_lock(&msgbuf_lock);
187 if (msgbuf_getcount(msgbufp) > 0)
188 revents |= events & (POLLIN | POLLRDNORM);
190 selrecord(td, &logsoftc.sc_selp);
191 mtx_unlock(&msgbuf_lock);
197 logkqfilter(struct cdev *dev, struct knote *kn)
200 if (kn->kn_filter != EVFILT_READ)
203 kn->kn_fop = &log_read_filterops;
206 mtx_lock(&msgbuf_lock);
207 knlist_add(&logsoftc.sc_selp.si_note, kn, 1);
208 mtx_unlock(&msgbuf_lock);
213 logkqread(struct knote *kn, long hint)
216 mtx_assert(&msgbuf_lock, MA_OWNED);
217 kn->kn_data = msgbuf_getcount(msgbufp);
218 return (kn->kn_data != 0);
222 logkqdetach(struct knote *kn)
225 mtx_lock(&msgbuf_lock);
226 knlist_remove(&logsoftc.sc_selp.si_note, kn, 1);
227 mtx_unlock(&msgbuf_lock);
231 logtimeout(void *arg)
236 if (log_wakeups_per_second < 1) {
237 printf("syslog wakeup is less than one. Adjusting to 1.\n");
238 log_wakeups_per_second = 1;
240 if (msgbuftrigger == 0) {
241 callout_schedule(&logsoftc.sc_callout,
242 hz / log_wakeups_per_second);
246 selwakeuppri(&logsoftc.sc_selp, LOG_RDPRI);
247 KNOTE_LOCKED(&logsoftc.sc_selp.si_note, 0);
248 if ((logsoftc.sc_state & LOG_ASYNC) && logsoftc.sc_sigio != NULL)
249 pgsigio(&logsoftc.sc_sigio, SIGIO, 0);
250 cv_broadcastpri(&log_wakeup, LOG_RDPRI);
251 callout_schedule(&logsoftc.sc_callout, hz / log_wakeups_per_second);
256 logioctl(struct cdev *dev, u_long com, caddr_t data, int flag, struct thread *td)
261 /* return number of characters immediately available */
263 *(int *)data = msgbuf_getcount(msgbufp);
270 mtx_lock(&msgbuf_lock);
272 logsoftc.sc_state |= LOG_ASYNC;
274 logsoftc.sc_state &= ~LOG_ASYNC;
275 mtx_unlock(&msgbuf_lock);
279 return (fsetown(*(int *)data, &logsoftc.sc_sigio));
282 *(int *)data = fgetown(&logsoftc.sc_sigio);
285 /* This is deprecated, FIOSETOWN should be used instead. */
287 return (fsetown(-(*(int *)data), &logsoftc.sc_sigio));
289 /* This is deprecated, FIOGETOWN should be used instead */
291 *(int *)data = -fgetown(&logsoftc.sc_sigio);
301 log_drvinit(void *unused)
304 cv_init(&log_wakeup, "klog");
305 callout_init_mtx(&logsoftc.sc_callout, &msgbuf_lock, 0);
306 knlist_init_mtx(&logsoftc.sc_selp.si_note, &msgbuf_lock);
307 make_dev_credf(MAKEDEV_ETERNAL, &log_cdevsw, 0, NULL, UID_ROOT,
308 GID_WHEEL, 0600, "klog");
311 SYSINIT(logdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE,log_drvinit,NULL);