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From: Jiri Bohac <jbohac@suse.cz>
To: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>, Jiri Bohac <jbohac@suse.cz>,
	linux-kernel@vger.kernel.org,
	Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: is printk() safe within a timekeeper_seq write section?
Date: Wed, 12 Mar 2014 10:21:25 +0100	[thread overview]
Message-ID: <20140312092125.GA30305@midget.suse.cz> (raw)
In-Reply-To: <531F8605.10003@linaro.org>

On Tue, Mar 11, 2014 at 02:54:13PM -0700, John Stultz wrote:
> Ok, so a generic solution is probably not going to be worth it then. My
> thought was that since we do a very limited amount of informational
> printks in the timekeeping code, we can be fairly safe delaying the
> print-out until we drop the locks.
> 
> For timekeeping, its really 4 call sites:
> * invalid inject_sleep_time deltas
> * > 11% clocksource freq adjustments
> * insert leap second
> * delete leap second

I believe these last two were made safe by 
commit ca4523cd (timekeeping: Shorten seq_count region). 

write_seqcount_begin(&timekeeper_seq) is now done after the
accumulate_nsecs_to_secs(tk) from where the printks are called.

Regards,

-- 
Jiri Bohac <jbohac@suse.cz>
SUSE Labs, SUSE CZ


  parent reply	other threads:[~2014-03-12  9:21 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-03-06 17:45 is printk() safe within a timekeeper_seq write section? Jiri Bohac
2014-03-11 19:29 ` John Stultz
2014-03-11 21:32   ` Thomas Gleixner
2014-03-11 21:54     ` John Stultz
2014-03-12  6:49       ` Peter Zijlstra
2014-03-12  9:21       ` Jiri Bohac [this message]
2014-03-28  0:49         ` John Stultz
2014-03-12  6:46     ` Peter Zijlstra
2014-03-12 14:34       ` Jan Kara
2014-03-12 15:06         ` Peter Zijlstra
2014-03-14 15:13           ` Jan Kara
2014-03-12 13:13     ` Jan Kara
2014-03-12  9:25   ` Peter Zijlstra
2014-03-12  9:18 ` Peter Zijlstra

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