NetBSD-5.0.2/sys/kern/subr_log.c
/* $NetBSD: subr_log.c,v 1.50 2008/04/28 20:24:04 martin Exp $ */
/*-
* Copyright (c) 2007, 2008 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Andrew Doran.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Copyright (c) 1982, 1986, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)subr_log.c 8.3 (Berkeley) 2/14/95
*/
/*
* Error log buffer for kernel printf's.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: subr_log.c,v 1.50 2008/04/28 20:24:04 martin Exp $");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/ioctl.h>
#include <sys/msgbuf.h>
#include <sys/file.h>
#include <sys/syslog.h>
#include <sys/conf.h>
#include <sys/select.h>
#include <sys/poll.h>
#include <sys/intr.h>
static void logsoftintr(void *);
static bool log_async;
static struct selinfo log_selp; /* process waiting on select call */
static pid_t log_pgid; /* process/group for async I/O */
static kcondvar_t log_cv;
static void *log_sih;
kmutex_t log_lock;
int log_open; /* also used in log() */
int msgbufmapped; /* is the message buffer mapped */
int msgbufenabled; /* is logging to the buffer enabled */
struct kern_msgbuf *msgbufp; /* the mapped buffer, itself. */
void
initmsgbuf(void *bf, size_t bufsize)
{
struct kern_msgbuf *mbp;
long new_bufs;
/* Sanity-check the given size. */
if (bufsize < sizeof(struct kern_msgbuf))
return;
mbp = msgbufp = (struct kern_msgbuf *)bf;
new_bufs = bufsize - offsetof(struct kern_msgbuf, msg_bufc);
if ((mbp->msg_magic != MSG_MAGIC) || (mbp->msg_bufs != new_bufs) ||
(mbp->msg_bufr < 0) || (mbp->msg_bufr >= mbp->msg_bufs) ||
(mbp->msg_bufx < 0) || (mbp->msg_bufx >= mbp->msg_bufs)) {
/*
* If the buffer magic number is wrong, has changed
* size (which shouldn't happen often), or is
* internally inconsistent, initialize it.
*/
memset(bf, 0, bufsize);
mbp->msg_magic = MSG_MAGIC;
mbp->msg_bufs = new_bufs;
}
/* mark it as ready for use. */
msgbufmapped = msgbufenabled = 1;
}
void
loginit(void)
{
mutex_init(&log_lock, MUTEX_DEFAULT, IPL_VM);
selinit(&log_selp);
cv_init(&log_cv, "klog");
log_sih = softint_establish(SOFTINT_CLOCK | SOFTINT_MPSAFE,
logsoftintr, NULL);
}
/*ARGSUSED*/
static int
logopen(dev_t dev, int flags, int mode, struct lwp *l)
{
struct kern_msgbuf *mbp = msgbufp;
int error = 0;
mutex_spin_enter(&log_lock);
if (log_open) {
error = EBUSY;
} else {
log_open = 1;
log_pgid = l->l_proc->p_pid; /* signal process only */
/*
* The message buffer is initialized during system
* configuration. If it's been clobbered, note that
* and return an error. (This allows a user to read
* the buffer via /dev/kmem, and try to figure out
* what clobbered it.
*/
if (mbp->msg_magic != MSG_MAGIC) {
msgbufenabled = 0;
error = ENXIO;
}
}
mutex_spin_exit(&log_lock);
return error;
}
/*ARGSUSED*/
static int
logclose(dev_t dev, int flag, int mode, struct lwp *l)
{
mutex_spin_enter(&log_lock);
log_pgid = 0;
log_open = 0;
log_async = 0;
mutex_spin_exit(&log_lock);
return 0;
}
/*ARGSUSED*/
static int
logread(dev_t dev, struct uio *uio, int flag)
{
struct kern_msgbuf *mbp = msgbufp;
long l;
int error = 0;
mutex_spin_enter(&log_lock);
while (mbp->msg_bufr == mbp->msg_bufx) {
if (flag & IO_NDELAY) {
mutex_spin_exit(&log_lock);
return EWOULDBLOCK;
}
error = cv_wait_sig(&log_cv, &log_lock);
if (error) {
mutex_spin_exit(&log_lock);
return error;
}
}
while (uio->uio_resid > 0) {
l = mbp->msg_bufx - mbp->msg_bufr;
if (l < 0)
l = mbp->msg_bufs - mbp->msg_bufr;
l = min(l, uio->uio_resid);
if (l == 0)
break;
mutex_spin_exit(&log_lock);
error = uiomove(&mbp->msg_bufc[mbp->msg_bufr], (int)l, uio);
mutex_spin_enter(&log_lock);
if (error)
break;
mbp->msg_bufr += l;
if (mbp->msg_bufr < 0 || mbp->msg_bufr >= mbp->msg_bufs)
mbp->msg_bufr = 0;
}
mutex_spin_exit(&log_lock);
return error;
}
/*ARGSUSED*/
static int
logpoll(dev_t dev, int events, struct lwp *l)
{
int revents = 0;
if (events & (POLLIN | POLLRDNORM)) {
mutex_spin_enter(&log_lock);
if (msgbufp->msg_bufr != msgbufp->msg_bufx)
revents |= events & (POLLIN | POLLRDNORM);
else
selrecord(l, &log_selp);
mutex_spin_exit(&log_lock);
}
return revents;
}
static void
filt_logrdetach(struct knote *kn)
{
mutex_spin_enter(&log_lock);
SLIST_REMOVE(&log_selp.sel_klist, kn, knote, kn_selnext);
mutex_spin_exit(&log_lock);
}
static int
filt_logread(struct knote *kn, long hint)
{
int rv;
if ((hint & NOTE_SUBMIT) == 0)
mutex_spin_enter(&log_lock);
if (msgbufp->msg_bufr == msgbufp->msg_bufx) {
rv = 0;
} else if (msgbufp->msg_bufr < msgbufp->msg_bufx) {
kn->kn_data = msgbufp->msg_bufx - msgbufp->msg_bufr;
rv = 1;
} else {
kn->kn_data = (msgbufp->msg_bufs - msgbufp->msg_bufr) +
msgbufp->msg_bufx;
rv = 1;
}
if ((hint & NOTE_SUBMIT) == 0)
mutex_spin_exit(&log_lock);
return rv;
}
static const struct filterops logread_filtops =
{ 1, NULL, filt_logrdetach, filt_logread };
static int
logkqfilter(dev_t dev, struct knote *kn)
{
struct klist *klist;
switch (kn->kn_filter) {
case EVFILT_READ:
klist = &log_selp.sel_klist;
kn->kn_fop = &logread_filtops;
break;
default:
return (EINVAL);
}
mutex_spin_enter(&log_lock);
kn->kn_hook = NULL;
SLIST_INSERT_HEAD(klist, kn, kn_selnext);
mutex_spin_exit(&log_lock);
return (0);
}
void
logwakeup(void)
{
if (!cold && log_open) {
mutex_spin_enter(&log_lock);
selnotify(&log_selp, 0, NOTE_SUBMIT);
if (log_async)
softint_schedule(log_sih);
cv_broadcast(&log_cv);
mutex_spin_exit(&log_lock);
}
}
static void
logsoftintr(void *cookie)
{
pid_t pid;
if ((pid = log_pgid) != 0)
fownsignal(pid, SIGIO, 0, 0, NULL);
}
/*ARGSUSED*/
static int
logioctl(dev_t dev, u_long com, void *data, int flag, struct lwp *lwp)
{
long l;
switch (com) {
/* return number of characters immediately available */
case FIONREAD:
mutex_spin_enter(&log_lock);
l = msgbufp->msg_bufx - msgbufp->msg_bufr;
if (l < 0)
l += msgbufp->msg_bufs;
mutex_spin_exit(&log_lock);
*(int *)data = l;
break;
case FIONBIO:
break;
case FIOASYNC:
/* No locking needed, 'thread private'. */
log_async = (*((int *)data) != 0);
break;
case TIOCSPGRP:
case FIOSETOWN:
return fsetown(&log_pgid, com, data);
case TIOCGPGRP:
case FIOGETOWN:
return fgetown(log_pgid, com, data);
default:
return (EPASSTHROUGH);
}
return (0);
}
void
logputchar(int c)
{
struct kern_msgbuf *mbp;
if (!cold)
mutex_spin_enter(&log_lock);
if (msgbufenabled) {
mbp = msgbufp;
if (mbp->msg_magic != MSG_MAGIC) {
/*
* Arguably should panic or somehow notify the
* user... but how? Panic may be too drastic,
* and would obliterate the message being kicked
* out (maybe a panic itself), and printf
* would invoke us recursively. Silently punt
* for now. If syslog is running, it should
* notice.
*/
msgbufenabled = 0;
} else {
mbp->msg_bufc[mbp->msg_bufx++] = c;
if (mbp->msg_bufx < 0 || mbp->msg_bufx >= mbp->msg_bufs)
mbp->msg_bufx = 0;
/* If the buffer is full, keep the most recent data. */
if (mbp->msg_bufr == mbp->msg_bufx) {
if (++mbp->msg_bufr >= mbp->msg_bufs)
mbp->msg_bufr = 0;
}
}
}
if (!cold)
mutex_spin_exit(&log_lock);
}
const struct cdevsw log_cdevsw = {
logopen, logclose, logread, nowrite, logioctl,
nostop, notty, logpoll, nommap, logkqfilter,
D_OTHER | D_MPSAFE
};