periodically save system time to hardware time-of-day clock
This is done in kern_ntptime, perhaps not the best place. This is done using resettodr(). Some features: - make save period configurable via tunable and sysctl - period of zero disables saving, setting a non-zero period re-enables it or reschedules it - do saving only if system clock is ntp-synchronized - save on shutdown Discussed with: des, Peter Jeremy <peterjeremy@acm.org> X-Maybe: save time near seconds boundary for better precision MFC after: 2 weeks
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svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=207360
@ -38,6 +38,7 @@ __FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/sysproto.h>
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#include <sys/eventhandler.h>
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#include <sys/kernel.h>
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#include <sys/priv.h>
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#include <sys/proc.h>
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@ -976,3 +977,67 @@ kern_adjtime(struct thread *td, struct timeval *delta, struct timeval *olddelta)
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return (0);
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}
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static struct callout resettodr_callout;
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static int resettodr_period = 1800;
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static void
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periodic_resettodr(void *arg __unused)
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{
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if (!ntp_is_time_error()) {
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mtx_lock(&Giant);
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resettodr();
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mtx_unlock(&Giant);
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}
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if (resettodr_period > 0)
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callout_schedule(&resettodr_callout, resettodr_period * hz);
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}
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static void
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shutdown_resettodr(void *arg __unused, int howto __unused)
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{
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callout_drain(&resettodr_callout);
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if (resettodr_period > 0 && !ntp_is_time_error()) {
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mtx_lock(&Giant);
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resettodr();
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mtx_unlock(&Giant);
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}
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}
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static int
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sysctl_resettodr_period(SYSCTL_HANDLER_ARGS)
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{
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int error;
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error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req);
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if (error || !req->newptr)
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return (error);
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if (resettodr_period == 0)
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callout_stop(&resettodr_callout);
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else
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callout_reset(&resettodr_callout, resettodr_period * hz,
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periodic_resettodr, NULL);
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return (0);
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}
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SYSCTL_PROC(_machdep, OID_AUTO, rtc_save_period, CTLTYPE_INT|CTLFLAG_RW,
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&resettodr_period, 1800, sysctl_resettodr_period, "I",
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"Save system time to RTC with this period (in seconds)");
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TUNABLE_INT("machdep.rtc_save_period", &resettodr_period);
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static void
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start_periodic_resettodr(void *arg __unused)
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{
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EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_resettodr, NULL,
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SHUTDOWN_PRI_FIRST);
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callout_init(&resettodr_callout, 1);
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if (resettodr_period == 0)
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return;
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callout_reset(&resettodr_callout, resettodr_period * hz,
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periodic_resettodr, NULL);
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}
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SYSINIT(periodic_resettodr, SI_SUB_RUN_SCHEDULER, SI_ORDER_ANY - 1,
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start_periodic_resettodr, NULL);
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