The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_log.c

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    1 /*-
    2  * Copyright (c) 1982, 1986, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 4. Neither the name of the University nor the names of its contributors
   14  *    may be used to endorse or promote products derived from this software
   15  *    without specific prior written permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  *
   29  *      @(#)subr_log.c  8.1 (Berkeley) 6/10/93
   30  */
   31 
   32 /*
   33  * Error log buffer for kernel printf's.
   34  */
   35 
   36 #include <sys/cdefs.h>
   37 __FBSDID("$FreeBSD$");
   38 
   39 #include <sys/param.h>
   40 #include <sys/systm.h>
   41 #include <sys/conf.h>
   42 #include <sys/proc.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>
   49 #include <sys/poll.h>
   50 #include <sys/filedesc.h>
   51 #include <sys/sysctl.h>
   52 
   53 #define LOG_RDPRI       (PZERO + 1)
   54 
   55 #define LOG_ASYNC       0x04
   56 #define LOG_RDWAIT      0x08
   57 
   58 static  d_open_t        logopen;
   59 static  d_close_t       logclose;
   60 static  d_read_t        logread;
   61 static  d_ioctl_t       logioctl;
   62 static  d_poll_t        logpoll;
   63 
   64 static  void logtimeout(void *arg);
   65 
   66 static struct cdevsw log_cdevsw = {
   67         .d_version =    D_VERSION,
   68         .d_flags =      D_NEEDGIANT,
   69         .d_open =       logopen,
   70         .d_close =      logclose,
   71         .d_read =       logread,
   72         .d_ioctl =      logioctl,
   73         .d_poll =       logpoll,
   74         .d_name =       "log",
   75 };
   76 
   77 static struct logsoftc {
   78         int     sc_state;               /* see above for possibilities */
   79         struct  selinfo sc_selp;        /* process waiting on select call */
   80         struct  sigio *sc_sigio;        /* information for async I/O */
   81         struct  callout sc_callout;     /* callout to wakeup syslog  */
   82 } logsoftc;
   83 
   84 int     log_open;                       /* also used in log() */
   85 
   86 /* Times per second to check for a pending syslog wakeup. */
   87 static int      log_wakeups_per_second = 5;
   88 SYSCTL_INT(_kern, OID_AUTO, log_wakeups_per_second, CTLFLAG_RW,
   89     &log_wakeups_per_second, 0, "");
   90 
   91 /*ARGSUSED*/
   92 static  int
   93 logopen(struct cdev *dev, int flags, int mode, struct thread *td)
   94 {
   95         if (log_open)
   96                 return (EBUSY);
   97         log_open = 1;
   98         callout_init(&logsoftc.sc_callout, 0);
   99         fsetown(td->td_proc->p_pid, &logsoftc.sc_sigio);        /* signal process only */
  100         if (log_wakeups_per_second < 1) {
  101                 printf("syslog wakeup is less than one.  Adjusting to 1.\n");
  102                 log_wakeups_per_second = 1;
  103         }
  104         callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
  105             logtimeout, NULL);
  106         return (0);
  107 }
  108 
  109 /*ARGSUSED*/
  110 static  int
  111 logclose(struct cdev *dev, int flag, int mode, struct thread *td)
  112 {
  113 
  114         log_open = 0;
  115         callout_stop(&logsoftc.sc_callout);
  116         logsoftc.sc_state = 0;
  117         funsetown(&logsoftc.sc_sigio);
  118         return (0);
  119 }
  120 
  121 /*ARGSUSED*/
  122 static  int
  123 logread(struct cdev *dev, struct uio *uio, int flag)
  124 {
  125         char buf[128];
  126         struct msgbuf *mbp = msgbufp;
  127         int error = 0, l, s;
  128 
  129         s = splhigh();
  130         while (msgbuf_getcount(mbp) == 0) {
  131                 if (flag & IO_NDELAY) {
  132                         splx(s);
  133                         return (EWOULDBLOCK);
  134                 }
  135                 logsoftc.sc_state |= LOG_RDWAIT;
  136                 if ((error = tsleep(mbp, LOG_RDPRI | PCATCH, "klog", 0))) {
  137                         splx(s);
  138                         return (error);
  139                 }
  140         }
  141         splx(s);
  142         logsoftc.sc_state &= ~LOG_RDWAIT;
  143 
  144         while (uio->uio_resid > 0) {
  145                 l = imin(sizeof(buf), uio->uio_resid);
  146                 l = msgbuf_getbytes(mbp, buf, l);
  147                 if (l == 0)
  148                         break;
  149                 error = uiomove(buf, l, uio);
  150                 if (error)
  151                         break;
  152         }
  153         return (error);
  154 }
  155 
  156 /*ARGSUSED*/
  157 static  int
  158 logpoll(struct cdev *dev, int events, struct thread *td)
  159 {
  160         int s;
  161         int revents = 0;
  162 
  163         s = splhigh();
  164 
  165         if (events & (POLLIN | POLLRDNORM)) {
  166                 if (msgbuf_getcount(msgbufp) > 0)
  167                         revents |= events & (POLLIN | POLLRDNORM);
  168                 else
  169                         selrecord(td, &logsoftc.sc_selp);
  170         }
  171         splx(s);
  172         return (revents);
  173 }
  174 
  175 static void
  176 logtimeout(void *arg)
  177 {
  178 
  179         if (!log_open)
  180                 return;
  181         if (log_wakeups_per_second < 1) {
  182                 printf("syslog wakeup is less than one.  Adjusting to 1.\n");
  183                 log_wakeups_per_second = 1;
  184         }
  185         if (msgbuftrigger == 0) {
  186                 callout_reset(&logsoftc.sc_callout,
  187                     hz / log_wakeups_per_second, logtimeout, NULL);
  188                 return;
  189         }
  190         msgbuftrigger = 0;
  191         selwakeuppri(&logsoftc.sc_selp, LOG_RDPRI);
  192         if ((logsoftc.sc_state & LOG_ASYNC) && logsoftc.sc_sigio != NULL)
  193                 pgsigio(&logsoftc.sc_sigio, SIGIO, 0);
  194         if (logsoftc.sc_state & LOG_RDWAIT) {
  195                 wakeup(msgbufp);
  196                 logsoftc.sc_state &= ~LOG_RDWAIT;
  197         }
  198         callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
  199             logtimeout, NULL);
  200 }
  201 
  202 /*ARGSUSED*/
  203 static  int
  204 logioctl(struct cdev *dev, u_long com, caddr_t data, int flag, struct thread *td)
  205 {
  206 
  207         switch (com) {
  208 
  209         /* return number of characters immediately available */
  210         case FIONREAD:
  211                 *(int *)data = msgbuf_getcount(msgbufp);
  212                 break;
  213 
  214         case FIONBIO:
  215                 break;
  216 
  217         case FIOASYNC:
  218                 if (*(int *)data)
  219                         logsoftc.sc_state |= LOG_ASYNC;
  220                 else
  221                         logsoftc.sc_state &= ~LOG_ASYNC;
  222                 break;
  223 
  224         case FIOSETOWN:
  225                 return (fsetown(*(int *)data, &logsoftc.sc_sigio));
  226 
  227         case FIOGETOWN:
  228                 *(int *)data = fgetown(&logsoftc.sc_sigio);
  229                 break;
  230 
  231         /* This is deprecated, FIOSETOWN should be used instead. */
  232         case TIOCSPGRP:
  233                 return (fsetown(-(*(int *)data), &logsoftc.sc_sigio));
  234 
  235         /* This is deprecated, FIOGETOWN should be used instead */
  236         case TIOCGPGRP:
  237                 *(int *)data = -fgetown(&logsoftc.sc_sigio);
  238                 break;
  239 
  240         default:
  241                 return (ENOTTY);
  242         }
  243         return (0);
  244 }
  245 
  246 static void
  247 log_drvinit(void *unused)
  248 {
  249 
  250         make_dev(&log_cdevsw, 0, UID_ROOT, GID_WHEEL, 0600, "klog");
  251 }
  252 
  253 SYSINIT(logdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE,log_drvinit,NULL)

Cache object: abdd1b1bf54ab2db6b7e2647406b80b1


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