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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 1.9 2006/06/13 08:12:03 dillon Exp $
39 * Error log buffer for kernel printf's.
42 #include <sys/param.h>
43 #include <sys/systm.h>
46 #include <sys/vnode.h>
47 #include <sys/filio.h>
48 #include <sys/ttycom.h>
49 #include <sys/msgbuf.h>
50 #include <sys/signalvar.h>
51 #include <sys/kernel.h>
53 #include <sys/filedesc.h>
54 #include <sys/sysctl.h>
55 #include <sys/thread2.h>
57 #define LOG_ASYNC 0x04
58 #define LOG_RDWAIT 0x08
60 static d_open_t logopen;
61 static d_close_t logclose;
62 static d_read_t logread;
63 static d_ioctl_t logioctl;
64 static d_poll_t logpoll;
66 static void logtimeout(void *arg);
69 static struct cdevsw log_cdevsw = {
83 /* strategy */ nostrategy,
88 static struct logsoftc {
89 int sc_state; /* see above for possibilities */
90 struct selinfo sc_selp; /* process waiting on select call */
91 struct sigio *sc_sigio; /* information for async I/O */
92 struct callout sc_callout; /* callout to wakeup syslog */
95 int log_open; /* also used in log() */
97 /* Times per second to check for a pending syslog wakeup. */
98 static int log_wakeups_per_second = 5;
99 SYSCTL_INT(_kern, OID_AUTO, log_wakeups_per_second, CTLFLAG_RW,
100 &log_wakeups_per_second, 0, "");
104 logopen(dev_t dev, int flags, int mode, struct thread *td)
106 struct proc *p = td->td_proc;
112 callout_init(&logsoftc.sc_callout);
113 fsetown(p->p_pid, &logsoftc.sc_sigio); /* signal process only */
114 callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
121 logclose(dev_t dev, int flag, int mode, struct thread *td)
125 callout_stop(&logsoftc.sc_callout);
126 logsoftc.sc_state = 0;
127 funsetown(logsoftc.sc_sigio);
133 logread(dev_t dev, struct uio *uio, int flag)
135 struct msgbuf *mbp = msgbufp;
140 while (mbp->msg_bufr == mbp->msg_bufx) {
141 if (flag & IO_NDELAY) {
143 return (EWOULDBLOCK);
145 logsoftc.sc_state |= LOG_RDWAIT;
146 if ((error = tsleep((caddr_t)mbp, PCATCH, "klog", 0))) {
152 logsoftc.sc_state &= ~LOG_RDWAIT;
154 while (uio->uio_resid > 0) {
155 l = mbp->msg_bufx - mbp->msg_bufr;
157 l = mbp->msg_size - mbp->msg_bufr;
158 l = min(l, uio->uio_resid);
161 error = uiomove((caddr_t)msgbufp->msg_ptr + mbp->msg_bufr,
166 if (mbp->msg_bufr >= mbp->msg_size)
174 logpoll(dev_t dev, int events, struct thread *td)
179 if (events & (POLLIN | POLLRDNORM)) {
180 if (msgbufp->msg_bufr != msgbufp->msg_bufx)
181 revents |= events & (POLLIN | POLLRDNORM);
183 selrecord(td, &logsoftc.sc_selp);
190 logtimeout(void *arg)
195 if (msgbuftrigger == 0) {
196 callout_reset(&logsoftc.sc_callout,
197 hz / log_wakeups_per_second, logtimeout, NULL);
201 selwakeup(&logsoftc.sc_selp);
202 if ((logsoftc.sc_state & LOG_ASYNC) && logsoftc.sc_sigio != NULL)
203 pgsigio(logsoftc.sc_sigio, SIGIO, 0);
204 if (logsoftc.sc_state & LOG_RDWAIT) {
205 wakeup((caddr_t)msgbufp);
206 logsoftc.sc_state &= ~LOG_RDWAIT;
208 callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
214 logioctl(dev_t dev, u_long com, caddr_t data, int flag, struct thread *td)
220 /* return number of characters immediately available */
223 l = msgbufp->msg_bufx - msgbufp->msg_bufr;
226 l += msgbufp->msg_size;
232 logsoftc.sc_state |= LOG_ASYNC;
234 logsoftc.sc_state &= ~LOG_ASYNC;
238 return (fsetown(*(int *)data, &logsoftc.sc_sigio));
241 *(int *)data = fgetown(logsoftc.sc_sigio);
244 /* This is deprecated, FIOSETOWN should be used instead. */
246 return (fsetown(-(*(int *)data), &logsoftc.sc_sigio));
248 /* This is deprecated, FIOGETOWN should be used instead */
250 *(int *)data = -fgetown(logsoftc.sc_sigio);
260 log_drvinit(void *unused)
262 cdevsw_add(&log_cdevsw, 0, 0);
263 make_dev(&log_cdevsw, 0, UID_ROOT, GID_WHEEL, 0600, "klog");
266 SYSINIT(logdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,log_drvinit,NULL)