ca1d2f657a
Normally msgbufp is locked using Giant. Switch it to use the msgbuf_lock. Instead of changing the tsleep() calls to msleep(), just convert it to condvar(9). In my opinion the locking around msgbuf_peekbytes() still remains questionable. It looks like locks are dropped while performing copies of multiple blocks to userspace, which may cause the msgbuf to be reset in the mean time. At least getting it underneath from Giant should make it a little easier for us to figure out how to solve that. Reminded by: rdivacky
263 lines
6.6 KiB
C
263 lines
6.6 KiB
C
/*-
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* Copyright (c) 1982, 1986, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)subr_log.c 8.1 (Berkeley) 6/10/93
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*/
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/*
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* Error log buffer for kernel printf's.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/conf.h>
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#include <sys/proc.h>
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#include <sys/vnode.h>
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#include <sys/filio.h>
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#include <sys/ttycom.h>
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#include <sys/msgbuf.h>
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#include <sys/signalvar.h>
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#include <sys/kernel.h>
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#include <sys/poll.h>
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#include <sys/filedesc.h>
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#include <sys/sysctl.h>
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#define LOG_RDPRI (PZERO + 1)
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#define LOG_ASYNC 0x04
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static d_open_t logopen;
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static d_close_t logclose;
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static d_read_t logread;
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static d_ioctl_t logioctl;
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static d_poll_t logpoll;
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static void logtimeout(void *arg);
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static struct cdevsw log_cdevsw = {
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.d_version = D_VERSION,
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.d_open = logopen,
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.d_close = logclose,
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.d_read = logread,
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.d_ioctl = logioctl,
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.d_poll = logpoll,
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.d_name = "log",
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};
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static struct logsoftc {
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int sc_state; /* see above for possibilities */
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struct selinfo sc_selp; /* process waiting on select call */
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struct sigio *sc_sigio; /* information for async I/O */
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struct callout sc_callout; /* callout to wakeup syslog */
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} logsoftc;
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int log_open; /* also used in log() */
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static struct cv log_wakeup;
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struct mtx msgbuf_lock;
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MTX_SYSINIT(msgbuf_lock, &msgbuf_lock, "msgbuf lock", MTX_DEF);
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/* Times per second to check for a pending syslog wakeup. */
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static int log_wakeups_per_second = 5;
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SYSCTL_INT(_kern, OID_AUTO, log_wakeups_per_second, CTLFLAG_RW,
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&log_wakeups_per_second, 0, "");
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/*ARGSUSED*/
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static int
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logopen(struct cdev *dev, int flags, int mode, struct thread *td)
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{
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if (log_wakeups_per_second < 1) {
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printf("syslog wakeup is less than one. Adjusting to 1.\n");
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log_wakeups_per_second = 1;
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}
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mtx_lock(&msgbuf_lock);
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if (log_open) {
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mtx_unlock(&msgbuf_lock);
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return (EBUSY);
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}
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log_open = 1;
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callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
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logtimeout, NULL);
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mtx_unlock(&msgbuf_lock);
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fsetown(td->td_proc->p_pid, &logsoftc.sc_sigio); /* signal process only */
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return (0);
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}
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/*ARGSUSED*/
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static int
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logclose(struct cdev *dev, int flag, int mode, struct thread *td)
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{
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funsetown(&logsoftc.sc_sigio);
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mtx_lock(&msgbuf_lock);
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callout_stop(&logsoftc.sc_callout);
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logsoftc.sc_state = 0;
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log_open = 0;
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mtx_unlock(&msgbuf_lock);
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return (0);
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}
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/*ARGSUSED*/
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static int
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logread(struct cdev *dev, struct uio *uio, int flag)
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{
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char buf[128];
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struct msgbuf *mbp = msgbufp;
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int error = 0, l;
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mtx_lock(&msgbuf_lock);
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while (msgbuf_getcount(mbp) == 0) {
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if (flag & IO_NDELAY) {
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mtx_unlock(&msgbuf_lock);
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return (EWOULDBLOCK);
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}
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if ((error = cv_wait_sig(&log_wakeup, &msgbuf_lock)) != 0) {
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mtx_unlock(&msgbuf_lock);
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return (error);
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}
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}
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while (uio->uio_resid > 0) {
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l = imin(sizeof(buf), uio->uio_resid);
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l = msgbuf_getbytes(mbp, buf, l);
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if (l == 0)
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break;
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mtx_unlock(&msgbuf_lock);
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error = uiomove(buf, l, uio);
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if (error || uio->uio_resid == 0)
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return (error);
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mtx_lock(&msgbuf_lock);
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}
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mtx_unlock(&msgbuf_lock);
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return (error);
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}
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/*ARGSUSED*/
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static int
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logpoll(struct cdev *dev, int events, struct thread *td)
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{
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int revents = 0;
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if (events & (POLLIN | POLLRDNORM)) {
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mtx_lock(&msgbuf_lock);
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if (msgbuf_getcount(msgbufp) > 0)
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revents |= events & (POLLIN | POLLRDNORM);
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else
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selrecord(td, &logsoftc.sc_selp);
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mtx_unlock(&msgbuf_lock);
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}
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return (revents);
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}
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static void
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logtimeout(void *arg)
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{
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if (!log_open)
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return;
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if (log_wakeups_per_second < 1) {
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printf("syslog wakeup is less than one. Adjusting to 1.\n");
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log_wakeups_per_second = 1;
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}
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if (msgbuftrigger == 0) {
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callout_schedule(&logsoftc.sc_callout,
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hz / log_wakeups_per_second);
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return;
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}
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msgbuftrigger = 0;
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selwakeuppri(&logsoftc.sc_selp, LOG_RDPRI);
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if ((logsoftc.sc_state & LOG_ASYNC) && logsoftc.sc_sigio != NULL)
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pgsigio(&logsoftc.sc_sigio, SIGIO, 0);
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cv_broadcastpri(&log_wakeup, LOG_RDPRI);
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callout_schedule(&logsoftc.sc_callout, hz / log_wakeups_per_second);
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}
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/*ARGSUSED*/
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static int
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logioctl(struct cdev *dev, u_long com, caddr_t data, int flag, struct thread *td)
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{
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switch (com) {
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/* return number of characters immediately available */
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case FIONREAD:
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*(int *)data = msgbuf_getcount(msgbufp);
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break;
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case FIONBIO:
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break;
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case FIOASYNC:
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mtx_lock(&msgbuf_lock);
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if (*(int *)data)
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logsoftc.sc_state |= LOG_ASYNC;
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else
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logsoftc.sc_state &= ~LOG_ASYNC;
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mtx_unlock(&msgbuf_lock);
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break;
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case FIOSETOWN:
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return (fsetown(*(int *)data, &logsoftc.sc_sigio));
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case FIOGETOWN:
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*(int *)data = fgetown(&logsoftc.sc_sigio);
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break;
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/* This is deprecated, FIOSETOWN should be used instead. */
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case TIOCSPGRP:
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return (fsetown(-(*(int *)data), &logsoftc.sc_sigio));
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/* This is deprecated, FIOGETOWN should be used instead */
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case TIOCGPGRP:
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*(int *)data = -fgetown(&logsoftc.sc_sigio);
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break;
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default:
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return (ENOTTY);
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}
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return (0);
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}
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static void
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log_drvinit(void *unused)
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{
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cv_init(&log_wakeup, "klog");
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callout_init_mtx(&logsoftc.sc_callout, &msgbuf_lock, 0);
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make_dev(&log_cdevsw, 0, UID_ROOT, GID_WHEEL, 0600, "klog");
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}
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SYSINIT(logdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE,log_drvinit,NULL);
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