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31 * @(#)subr_log.c 8.1 (Berkeley) 6/10/93
35 * Error log buffer for kernel printf's.
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
41 #include <sys/param.h>
42 #include <sys/systm.h>
45 #include <sys/vnode.h>
46 #include <sys/filio.h>
47 #include <sys/ttycom.h>
48 #include <sys/msgbuf.h>
49 #include <sys/signalvar.h>
50 #include <sys/kernel.h>
52 #include <sys/filedesc.h>
53 #include <sys/sysctl.h>
55 #define LOG_RDPRI (PZERO + 1)
57 #define LOG_ASYNC 0x04
59 static d_open_t logopen;
60 static d_close_t logclose;
61 static d_read_t logread;
62 static d_ioctl_t logioctl;
63 static d_poll_t logpoll;
64 static d_kqfilter_t logkqfilter;
66 static void logtimeout(void *arg);
68 static struct cdevsw log_cdevsw = {
69 .d_version = D_VERSION,
75 .d_kqfilter = logkqfilter,
79 static int logkqread(struct knote *note, long hint);
80 static void logkqdetach(struct knote *note);
82 static struct filterops log_read_filterops = {
85 .f_detach = logkqdetach,
89 static struct logsoftc {
90 int sc_state; /* see above for possibilities */
91 struct selinfo sc_selp; /* process waiting on select call */
92 struct sigio *sc_sigio; /* information for async I/O */
93 struct callout sc_callout; /* callout to wakeup syslog */
96 int log_open; /* also used in log() */
97 static struct cv log_wakeup;
98 struct mtx msgbuf_lock;
99 MTX_SYSINIT(msgbuf_lock, &msgbuf_lock, "msgbuf lock", MTX_DEF);
101 /* Times per second to check for a pending syslog wakeup. */
102 static int log_wakeups_per_second = 5;
103 SYSCTL_INT(_kern, OID_AUTO, log_wakeups_per_second, CTLFLAG_RW,
104 &log_wakeups_per_second, 0, "");
108 logopen(struct cdev *dev, int flags, int mode, struct thread *td)
111 if (log_wakeups_per_second < 1) {
112 printf("syslog wakeup is less than one. Adjusting to 1.\n");
113 log_wakeups_per_second = 1;
116 mtx_lock(&msgbuf_lock);
118 mtx_unlock(&msgbuf_lock);
122 callout_reset_sbt(&logsoftc.sc_callout,
123 SBT_1S / log_wakeups_per_second, 0, logtimeout, NULL, C_PREL(1));
124 mtx_unlock(&msgbuf_lock);
126 fsetown(td->td_proc->p_pid, &logsoftc.sc_sigio); /* signal process only */
132 logclose(struct cdev *dev, int flag, int mode, struct thread *td)
135 funsetown(&logsoftc.sc_sigio);
137 mtx_lock(&msgbuf_lock);
138 callout_stop(&logsoftc.sc_callout);
139 logsoftc.sc_state = 0;
141 mtx_unlock(&msgbuf_lock);
148 logread(struct cdev *dev, struct uio *uio, int flag)
151 struct msgbuf *mbp = msgbufp;
154 mtx_lock(&msgbuf_lock);
155 while (msgbuf_getcount(mbp) == 0) {
156 if (flag & IO_NDELAY) {
157 mtx_unlock(&msgbuf_lock);
158 return (EWOULDBLOCK);
160 if ((error = cv_wait_sig(&log_wakeup, &msgbuf_lock)) != 0) {
161 mtx_unlock(&msgbuf_lock);
166 while (uio->uio_resid > 0) {
167 l = imin(sizeof(buf), uio->uio_resid);
168 l = msgbuf_getbytes(mbp, buf, l);
171 mtx_unlock(&msgbuf_lock);
172 error = uiomove(buf, l, uio);
173 if (error || uio->uio_resid == 0)
175 mtx_lock(&msgbuf_lock);
177 mtx_unlock(&msgbuf_lock);
183 logpoll(struct cdev *dev, int events, struct thread *td)
187 if (events & (POLLIN | POLLRDNORM)) {
188 mtx_lock(&msgbuf_lock);
189 if (msgbuf_getcount(msgbufp) > 0)
190 revents |= events & (POLLIN | POLLRDNORM);
192 selrecord(td, &logsoftc.sc_selp);
193 mtx_unlock(&msgbuf_lock);
199 logkqfilter(struct cdev *dev, struct knote *kn)
202 if (kn->kn_filter != EVFILT_READ)
205 kn->kn_fop = &log_read_filterops;
208 mtx_lock(&msgbuf_lock);
209 knlist_add(&logsoftc.sc_selp.si_note, kn, 1);
210 mtx_unlock(&msgbuf_lock);
215 logkqread(struct knote *kn, long hint)
218 mtx_assert(&msgbuf_lock, MA_OWNED);
219 kn->kn_data = msgbuf_getcount(msgbufp);
220 return (kn->kn_data != 0);
224 logkqdetach(struct knote *kn)
227 mtx_lock(&msgbuf_lock);
228 knlist_remove(&logsoftc.sc_selp.si_note, kn, 1);
229 mtx_unlock(&msgbuf_lock);
233 logtimeout(void *arg)
238 if (msgbuftrigger == 0)
241 selwakeuppri(&logsoftc.sc_selp, LOG_RDPRI);
242 KNOTE_LOCKED(&logsoftc.sc_selp.si_note, 0);
243 if ((logsoftc.sc_state & LOG_ASYNC) && logsoftc.sc_sigio != NULL)
244 pgsigio(&logsoftc.sc_sigio, SIGIO, 0);
245 cv_broadcastpri(&log_wakeup, LOG_RDPRI);
247 if (log_wakeups_per_second < 1) {
248 printf("syslog wakeup is less than one. Adjusting to 1.\n");
249 log_wakeups_per_second = 1;
251 callout_reset_sbt(&logsoftc.sc_callout,
252 SBT_1S / log_wakeups_per_second, 0, logtimeout, NULL, C_PREL(1));
257 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);