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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;
63 static void logtimeout(void *arg);
65 static struct cdevsw log_cdevsw = {
66 .d_version = D_VERSION,
75 static struct logsoftc {
76 int sc_state; /* see above for possibilities */
77 struct selinfo sc_selp; /* process waiting on select call */
78 struct sigio *sc_sigio; /* information for async I/O */
79 struct callout sc_callout; /* callout to wakeup syslog */
82 int log_open; /* also used in log() */
83 static struct cv log_wakeup;
84 struct mtx msgbuf_lock;
85 MTX_SYSINIT(msgbuf_lock, &msgbuf_lock, "msgbuf lock", MTX_DEF);
87 /* Times per second to check for a pending syslog wakeup. */
88 static int log_wakeups_per_second = 5;
89 SYSCTL_INT(_kern, OID_AUTO, log_wakeups_per_second, CTLFLAG_RW,
90 &log_wakeups_per_second, 0, "");
94 logopen(struct cdev *dev, int flags, int mode, struct thread *td)
97 if (log_wakeups_per_second < 1) {
98 printf("syslog wakeup is less than one. Adjusting to 1.\n");
99 log_wakeups_per_second = 1;
102 mtx_lock(&msgbuf_lock);
104 mtx_unlock(&msgbuf_lock);
108 callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
110 mtx_unlock(&msgbuf_lock);
112 fsetown(td->td_proc->p_pid, &logsoftc.sc_sigio); /* signal process only */
118 logclose(struct cdev *dev, int flag, int mode, struct thread *td)
121 funsetown(&logsoftc.sc_sigio);
123 mtx_lock(&msgbuf_lock);
124 callout_stop(&logsoftc.sc_callout);
125 logsoftc.sc_state = 0;
127 mtx_unlock(&msgbuf_lock);
134 logread(struct cdev *dev, struct uio *uio, int flag)
137 struct msgbuf *mbp = msgbufp;
140 mtx_lock(&msgbuf_lock);
141 while (msgbuf_getcount(mbp) == 0) {
142 if (flag & IO_NDELAY) {
143 mtx_unlock(&msgbuf_lock);
144 return (EWOULDBLOCK);
146 if ((error = cv_wait_sig(&log_wakeup, &msgbuf_lock)) != 0) {
147 mtx_unlock(&msgbuf_lock);
152 while (uio->uio_resid > 0) {
153 l = imin(sizeof(buf), uio->uio_resid);
154 l = msgbuf_getbytes(mbp, buf, l);
157 mtx_unlock(&msgbuf_lock);
158 error = uiomove(buf, l, uio);
159 if (error || uio->uio_resid == 0)
161 mtx_lock(&msgbuf_lock);
163 mtx_unlock(&msgbuf_lock);
169 logpoll(struct cdev *dev, int events, struct thread *td)
173 if (events & (POLLIN | POLLRDNORM)) {
174 mtx_lock(&msgbuf_lock);
175 if (msgbuf_getcount(msgbufp) > 0)
176 revents |= events & (POLLIN | POLLRDNORM);
178 selrecord(td, &logsoftc.sc_selp);
179 mtx_unlock(&msgbuf_lock);
185 logtimeout(void *arg)
190 if (log_wakeups_per_second < 1) {
191 printf("syslog wakeup is less than one. Adjusting to 1.\n");
192 log_wakeups_per_second = 1;
194 if (msgbuftrigger == 0) {
195 callout_schedule(&logsoftc.sc_callout,
196 hz / log_wakeups_per_second);
200 selwakeuppri(&logsoftc.sc_selp, LOG_RDPRI);
201 if ((logsoftc.sc_state & LOG_ASYNC) && logsoftc.sc_sigio != NULL)
202 pgsigio(&logsoftc.sc_sigio, SIGIO, 0);
203 cv_broadcastpri(&log_wakeup, LOG_RDPRI);
204 callout_schedule(&logsoftc.sc_callout, hz / log_wakeups_per_second);
209 logioctl(struct cdev *dev, u_long com, caddr_t data, int flag, struct thread *td)
214 /* return number of characters immediately available */
216 *(int *)data = msgbuf_getcount(msgbufp);
223 mtx_lock(&msgbuf_lock);
225 logsoftc.sc_state |= LOG_ASYNC;
227 logsoftc.sc_state &= ~LOG_ASYNC;
228 mtx_unlock(&msgbuf_lock);
232 return (fsetown(*(int *)data, &logsoftc.sc_sigio));
235 *(int *)data = fgetown(&logsoftc.sc_sigio);
238 /* This is deprecated, FIOSETOWN should be used instead. */
240 return (fsetown(-(*(int *)data), &logsoftc.sc_sigio));
242 /* This is deprecated, FIOGETOWN should be used instead */
244 *(int *)data = -fgetown(&logsoftc.sc_sigio);
254 log_drvinit(void *unused)
257 cv_init(&log_wakeup, "klog");
258 callout_init_mtx(&logsoftc.sc_callout, &msgbuf_lock, 0);
259 make_dev_credf(MAKEDEV_ETERNAL, &log_cdevsw, 0, NULL, UID_ROOT,
260 GID_WHEEL, 0600, "klog");
263 SYSINIT(logdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE,log_drvinit,NULL);