Delay waking up processes select'ing on the log device directly from
the kernel console. Instead, change logwakeup() to set a flag in the softc. A callout then wakes up every so often and wakes up any processes selecting on /dev/log (such as syslogd) if the flag is set. By default this callout fires 5 times a second, but that can be adjusted by the sysctl kern.log_wakeups_per_second. Reviewed by: phk
This commit is contained in:
parent
38d66a0de3
commit
a9b1370731
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=70069
@ -50,11 +50,13 @@
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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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#define LOG_RDWAIT 0x08
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#define LOG_NEEDWAKEUP 0x10
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static d_open_t logopen;
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static d_close_t logclose;
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@ -62,6 +64,8 @@ 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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#define CDEV_MAJOR 7
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static struct cdevsw log_cdevsw = {
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/* open */ logopen,
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@ -84,10 +88,16 @@ 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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/* 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(dev_t dev, int flags, int mode, struct proc *p)
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@ -95,7 +105,10 @@ logopen(dev_t dev, int flags, int mode, struct proc *p)
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if (log_open)
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return (EBUSY);
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log_open = 1;
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callout_init(&logsoftc.sc_callout, 0);
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fsetown(p->p_pid, &logsoftc.sc_sigio); /* signal process only */
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callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
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logtimeout, NULL);
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return (0);
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}
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@ -104,6 +117,7 @@ static int
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logclose(dev_t dev, int flag, int mode, struct proc *p)
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{
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callout_stop(&logsoftc.sc_callout);
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log_open = 0;
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logsoftc.sc_state = 0;
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funsetown(logsoftc.sc_sigio);
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@ -175,6 +189,19 @@ logpoll(dev_t dev, int events, struct proc *p)
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void
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logwakeup(void)
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{
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if (!log_open)
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return;
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logsoftc.sc_state |= LOG_NEEDWAKEUP;
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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 ((logsoftc.sc_state & LOG_NEEDWAKEUP) == 0)
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return;
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logsoftc.sc_state &= ~LOG_NEEDWAKEUP;
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if (!log_open)
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return;
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selwakeup(&logsoftc.sc_selp);
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@ -184,6 +211,8 @@ logwakeup(void)
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wakeup((caddr_t)msgbufp);
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logsoftc.sc_state &= ~LOG_RDWAIT;
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}
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callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
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logtimeout, NULL);
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}
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/*ARGSUSED*/
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