Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757957AbYCNUYT (ORCPT ); Fri, 14 Mar 2008 16:24:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753012AbYCNUYL (ORCPT ); Fri, 14 Mar 2008 16:24:11 -0400 Received: from e4.ny.us.ibm.com ([32.97.182.144]:54256 "EHLO e4.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751732AbYCNUYJ (ORCPT ); Fri, 14 Mar 2008 16:24:09 -0400 Subject: Re: [PATCH 8/8] handle leap second via timer From: john stultz To: zippel@linux-m68k.org Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org In-Reply-To: <20080314195737.212526899@linux-m68k.org> References: <20080314184001.695807682@linux-m68k.org> <20080314195737.212526899@linux-m68k.org> Content-Type: text/plain Date: Fri, 14 Mar 2008 13:24:04 -0700 Message-Id: <1205526244.6122.5.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.12.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3693 Lines: 119 On Fri, 2008-03-14 at 19:40 +0100, zippel@linux-m68k.org wrote: > plain text document attachment (leap_sec) > Remove the leap second handling from second_overflow(), which doesn't > has to check for it every second anymore. With CONFIG_NO_HZ this also > makes sure the leap second is handled close to the full second. > Additionally this makes it possible to abort a leap second properly > by resetting the STA_INS/STA_DEL status bits. > > Signed-off-by: Roman Zippel Looks interesting. Small comment below. > -void second_overflow(void) > +static enum hrtimer_restart ntp_leap_second(struct hrtimer *timer) > { > - s64 time_adj; > + enum hrtimer_restart res = HRTIMER_NORESTART; > > - /* Bump the maxerror field */ > - time_maxerror += MAXFREQ / NSEC_PER_USEC; > - if (time_maxerror > NTP_PHASE_LIMIT) { > - time_maxerror = NTP_PHASE_LIMIT; > - time_status |= STA_UNSYNC; > - } > + write_seqlock_irq(&xtime_lock); > > - /* > - * Leap second processing. If in leap-insert state at the end of the > - * day, the system clock is set back one second; if in leap-delete > - * state, the system clock is set ahead one second. The microtime() > - * routine or external clock driver will insure that reported time is > - * always monotonic. The ugly divides should be replaced. > - */ > switch (time_state) { > case TIME_OK: > - if (time_status & STA_INS) > - time_state = TIME_INS; > - else if (time_status & STA_DEL) > - time_state = TIME_DEL; > break; > case TIME_INS: > - if (xtime.tv_sec % 86400 == 0) { > - xtime.tv_sec--; > - wall_to_monotonic.tv_sec++; > - time_state = TIME_OOP; > - printk(KERN_NOTICE "Clock: inserting leap second " > - "23:59:60 UTC\n"); > - } > + xtime.tv_sec--; > + wall_to_monotonic.tv_sec++; > + time_state = TIME_OOP; > + printk(KERN_NOTICE "Clock: " > + "inserting leap second 23:59:60 UTC\n"); > + leap_timer.expires = ktime_add_ns(leap_timer.expires, > + NSEC_PER_SEC); > + res = HRTIMER_RESTART; > break; > case TIME_DEL: > - if ((xtime.tv_sec + 1) % 86400 == 0) { > - xtime.tv_sec++; > - time_tai--; > - wall_to_monotonic.tv_sec--; > - time_state = TIME_WAIT; > - printk(KERN_NOTICE "Clock: deleting leap second " > - "23:59:59 UTC\n"); > - } > + xtime.tv_sec++; > + time_tai--; > + wall_to_monotonic.tv_sec--; > + time_state = TIME_WAIT; > + printk(KERN_NOTICE "Clock: " > + "deleting leap second 23:59:59 UTC\n"); > break; > case TIME_OOP: > time_tai++; > time_state = TIME_WAIT; > - break; > + /* fall through */ > case TIME_WAIT: > if (!(time_status & (STA_INS | STA_DEL))) > time_state = TIME_OK; > + break; > + } > + update_vsyscall(&xtime, clock); > + > Index: linux-2.6/include/linux/clocksource.h > =================================================================== > --- linux-2.6.orig/include/linux/clocksource.h 2008-03-10 19:50:33.000000000 +0100 > +++ linux-2.6/include/linux/clocksource.h 2008-03-13 10:33:24.000000000 +0100 > @@ -93,6 +93,8 @@ struct clocksource { > #endif > }; > > +extern struct clocksource *clock; /* current clocksource */ > + > /* > * Clock source flags bits:: > */ Instead of exporting the clocksource making it global, could you use a timekeeping_insert/remove_second() style interface? That would help remove the xtime/wall_to_monotonic references in ntp.c as well, cleaning up things nicely. thanks -john -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/