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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 $
38 * Error log buffer for kernel printf's.
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
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 = {
77 /* strategy */ nostrategy,
86 static struct logsoftc {
87 int sc_state; /* see above for possibilities */
88 struct selinfo sc_selp; /* process waiting on select call */
89 struct sigio *sc_sigio; /* information for async I/O */
90 struct callout sc_callout; /* callout to wakeup syslog */
93 int log_open; /* also used in log() */
95 /* Times per second to check for a pending syslog wakeup. */
96 static int log_wakeups_per_second = 5;
97 SYSCTL_INT(_kern, OID_AUTO, log_wakeups_per_second, CTLFLAG_RW,
98 &log_wakeups_per_second, 0, "");
102 logopen(dev_t dev, int flags, int mode, struct proc *p)
107 callout_init(&logsoftc.sc_callout);
108 fsetown(p->p_pid, &logsoftc.sc_sigio); /* signal process only */
109 callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
116 logclose(dev_t dev, int flag, int mode, struct proc *p)
120 callout_stop(&logsoftc.sc_callout);
121 logsoftc.sc_state = 0;
122 funsetown(logsoftc.sc_sigio);
128 logread(dev_t dev, struct uio *uio, int flag)
130 struct msgbuf *mbp = msgbufp;
136 while (mbp->msg_bufr == mbp->msg_bufx) {
137 if (flag & IO_NDELAY) {
139 return (EWOULDBLOCK);
141 logsoftc.sc_state |= LOG_RDWAIT;
142 if ((error = tsleep((caddr_t)mbp, LOG_RDPRI | PCATCH,
149 logsoftc.sc_state &= ~LOG_RDWAIT;
151 while (uio->uio_resid > 0) {
152 l = mbp->msg_bufx - mbp->msg_bufr;
154 l = mbp->msg_size - mbp->msg_bufr;
155 l = min(l, uio->uio_resid);
158 error = uiomove((caddr_t)msgbufp->msg_ptr + mbp->msg_bufr,
163 if (mbp->msg_bufr >= mbp->msg_size)
171 logpoll(dev_t dev, int events, struct proc *p)
178 if (events & (POLLIN | POLLRDNORM)) {
179 if (msgbufp->msg_bufr != msgbufp->msg_bufx)
180 revents |= events & (POLLIN | POLLRDNORM);
182 selrecord(p, &logsoftc.sc_selp);
189 logtimeout(void *arg)
194 if (msgbuftrigger == 0) {
195 callout_reset(&logsoftc.sc_callout,
196 hz / log_wakeups_per_second, logtimeout, NULL);
200 selwakeup(&logsoftc.sc_selp);
201 if ((logsoftc.sc_state & LOG_ASYNC) && logsoftc.sc_sigio != NULL)
202 pgsigio(logsoftc.sc_sigio, SIGIO, 0);
203 if (logsoftc.sc_state & LOG_RDWAIT) {
204 wakeup((caddr_t)msgbufp);
205 logsoftc.sc_state &= ~LOG_RDWAIT;
207 callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
213 logioctl(dev_t dev, u_long com, caddr_t data, int flag, struct proc *p)
220 /* return number of characters immediately available */
223 l = msgbufp->msg_bufx - msgbufp->msg_bufr;
226 l += msgbufp->msg_size;
235 logsoftc.sc_state |= LOG_ASYNC;
237 logsoftc.sc_state &= ~LOG_ASYNC;
241 return (fsetown(*(int *)data, &logsoftc.sc_sigio));
244 *(int *)data = fgetown(logsoftc.sc_sigio);
247 /* This is deprecated, FIOSETOWN should be used instead. */
249 return (fsetown(-(*(int *)data), &logsoftc.sc_sigio));
251 /* This is deprecated, FIOGETOWN should be used instead */
253 *(int *)data = -fgetown(logsoftc.sc_sigio);
263 log_drvinit(void *unused)
266 make_dev(&log_cdevsw, 0, UID_ROOT, GID_WHEEL, 0600, "klog");
269 SYSINIT(logdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,log_drvinit,NULL)