linux-kernel - Re: [PATCH RFC V2 3/6] time: keep track of the pending utc/tai threshold

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Date:	Mon, 21 May 2012 11:09:51 -0700
From:	John Stultz <john.stultz@...aro.org>
To:	Richard Cochran <richardcochran@...il.com>
CC:	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH RFC V2 3/6] time: keep track of the pending utc/tai threshold

On 05/18/2012 07:09 AM, Richard Cochran wrote:
> This patch introduces time keeping variables to track the next
> mini-epoch between the UTC and TAI timescales. A leap second occurs
> one second before a mini-epoch. When no leap second is pending, then
> the epoch is set to the far future, LONG_MAX.
>
> This code will become useful later on for providing correct time
> surrounding a leap second.
>
> Signed-off-by: Richard Cochran<richardcochran@...il.com>
> ---
>   kernel/time/timekeeping.c |   14 ++++++++++++++
>   1 files changed, 14 insertions(+), 0 deletions(-)
>
> diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
> index d66b213..ac04de4 100644
> --- a/kernel/time/timekeeping.c
> +++ b/kernel/time/timekeeping.c
> @@ -70,6 +70,19 @@ struct timekeeper {
>   	/* The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock. */
>   	struct timespec raw_time;
>
> +	/* The current TAI - UTC offset */
> +	time_t tai_offset;
> +	/* The UTC time of the next leap second epoch */
> +	time_t utc_epoch;

How about leap_utc_epoch just to be more clear?

> +	/* Tracks where we stand with regard to leap the second epoch. */
> +	enum {
> +		LEAP_IDLE,
> +		LEAP_INS_PENDING,
> +		LEAP_INS_DONE,
> +		LEAP_DEL_PENDING,
> +		LEAP_DEL_DONE,
> +	} leap_state;
> +
For continuity,  would it make more sense for these to named closer to 
the NTP time_state values, or maybe reworked to make use of them?  Not 
sure if its worth having separate state machines in the timekeeping code 
and the ntp code, but maybe I'm not seeing a necessary detail here?


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