David,
On Mon, 12 Nov 2007, David P. Reed wrote:
> From: David P. Reed
>
> Fix two bugs in arch/x86/kernel/time_64.c that affect the x86_64 kernel. 1) a
> repeatable hard freeze due to interrupts when the ntpd service calls
> update_persistent_clock(), 2) potentially unstable PC RTC timer values when
> timer is read.
1) Please send separate patches for separate problems.
2) Your patch is white space damaged and does not apply. Please run it
through scripts/checkpatch.pl before submitting, maybe send it to
yourself first and verify that it applies correctly.
> Signed-off-by: David P. Reed <[email protected]>
> ---
> More explanation:
> 1) A repeatable but randomly timed freeze has been happening in Fedora 6 and 7
> for the last year, whenever I run the ntpd service on my AMD64x2 HP Pavilion
> dv9000z laptop. This freeze is due to the use of spin_lock(&rtc_lock) under
> the assumption (per a bad comment) that set_rtc_mmss is called only with
> interrupts disabled. The call from ntp.c to update_persistent_clock is made
> with interrupts enabled.
Good catch.
> 2) the use of an incorrect technique for reading the standard PC RTC timer,
> which is documented to "disconnect" time registers from the bus while updates
> are in progress. The use of UIP flag while interrupts are disabled to protect
> a 244 microsecond window is one of the Motorola spec sheet's documented ways
> to read the RTC time registers reliably. I realize that not all "clones" of
> the
of the what ?
Also put the detailed description into the patch comment, please.
> The patch updates the misleading comments and minimizes the amount of time
> that the kernel disables interrupts.
>
> I have thoroughly tested this patch on a number of x86_64 machines with
> various numbers of cores and chipsets, using 2.6.24rc2 kernel source. Note
> that while testing the ntp code I found another bug in kernel/time/ntp.c which
> is independent of this fix - neither patch requires the other.
>
> If possible, I'd love to see the patch merged with 2.6.24, and even with
> 2.6.23.
Care to resend ?
Thanks,
tglx
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