linux-kernel - Re: [PATCH RFC V2 4/6] time: introduce leap second functional interface

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Message-ID: <4FBAA499.1070905@linaro.org>
Date:	Mon, 21 May 2012 13:24:57 -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 4/6] time: introduce leap second functional interface

On 05/21/2012 12:18 PM, Richard Cochran wrote:
> On Mon, May 21, 2012 at 11:01:03AM -0700, John Stultz wrote:
>> On 05/18/2012 07:09 AM, Richard Cochran wrote:
>>> +
>>> +int timekeeping_gettod_status(struct timespec *ts, time_t *offset);
>>> +
>>> +void timekeeping_delete_leap_second(void);
>>> +
>>> +void timekeeping_finish_leap_second(void);
>>> +
>>> +void timekeeping_insert_leap_second(void);
>>> +
>>> +#endif
>> Why not just add these to time.h?
> This is a private interface only for ntp.c, not for the whole rest of
> the kernel via time.h.
Hrm.  I prefer to keep things fairly flat (even having time.h and 
timex.h bugs me somewhat).  But having such a separation could be 
useful, but maybe at a slightly more coarse level. Something like 
timekeeping-internal.h and time.h, splitting all the general accessors 
away from the non-general.

I just don't want to have a ton of stray .h files, but maybe I'm 
prematurely worrying about it.

> BTW this highlights the very icky incestuous relationship between
> ntp.c and timekeeper.c. Probably there should be a comment documenting
> the (unspoken) locking sequence for ntp_lock and timekeeper.lock.
>
The locking order is pretty straight forward: timekeeper.lock -> 
ntp_lock.   This only gets messy when you require timekeeping data from 
the ntp context, but usually we provide the required data via the 
caller.  But better documentation is always welcome.

thanks
-john

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