Commit:     fa6a1a554b50cbb7763f6907e6fef927ead480d9
Parent:     d0974b11e0741034fc5d22838b9cb85402a280d6
Author:     David P. Reed <[EMAIL PROTECTED]>
AuthorDate: Wed Nov 14 17:49:21 2007 -0500
Committer:  Thomas Gleixner <[EMAIL PROTECTED](none)>
CommitDate: Sat Nov 17 16:27:01 2007 +0100

    ntp: fix typo that makes sync_cmos_clock erratic
    Fix a typo in ntp.c that has caused updating of the persistent (RTC)
    clock when synced to NTP to behave erratically.
    When debugging a freeze that arises on my AMD64 machines when I
    run the ntpd service, I added a number of printk's to monitor the
    sync_cmos_clock procedure.  I discovered that it was not syncing to
    cmos RTC every 11 minutes as documented, but instead would keep trying
    every second for hours at a time.  The reason turned out to be a typo
    in sync_cmos_clock, where it attempts to ensure that
    update_persistent_clock is called very close to 500 msec. after a 1
    second boundary (required by the PC RTC's spec). That typo referred to
    "xtime" in one spot, rather than "now", which is derived from "xtime"
    but not equal to it.  This makes the test erratic, creating a
    "coin-flip" that decides when update_persistent_clock is called - when
    it is called, which is rarely, it may be at any time during the one
    second period, rather than close to 500 msec, so the value written is
    needlessly incorrect, too.
    Signed-off-by: David P. Reed
    Signed-off-by: Thomas Gleixner <[EMAIL PROTECTED]>
 kernel/time/ntp.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index de6a2d6..14a2ecf 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -205,7 +205,7 @@ static void sync_cmos_clock(unsigned long dummy)
-       if (abs(xtime.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec / 2)
+       if (abs(now.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec / 2)
                fail = update_persistent_clock(now);
        next.tv_nsec = (NSEC_PER_SEC / 2) - now.tv_nsec;
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