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Message-ID: <3ae3aa420901031201h3af1f03ct3f9d13db4a793e77@mail.gmail.com>
Date: Sat, 3 Jan 2009 14:01:20 -0600
From: "Linas Vepstas" <linasvepstas@gmail.com>
Reply-To: linasvepstas@gmail.com
To: "Chris Adams" <cmadams@hiwaay.net>
Subject: Re: [PATCH] v2 Re: Bug: Status/Summary of slashdot leap-second crash on new years 2008-2009
Cc: "Duane Griffin" <duaneg@dghda.com>, linux-kernel@vger.kernel.org,
       "Thomas Gleixner" <tglx@linutronix.de>,
       "Paul Gortmaker" <p_gortmaker@yahoo.com>,
       "Alessandro Zummo" <a.zummo@towertech.it>, rtc-linux@googlegroups.com
In-Reply-To: <20090103180148.GA1375968@hiwaay.net>
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2009/1/3 Chris Adams <cmadams@hiwaay.net>:

>
> From: Chris Adams <cmadams@hiwaay.net>
>
> The code to handle leap seconds printks an information message when the
> second is inserted or deleted.  It does this while holding xtime_lock.
> However, printk wakes up klogd, and in some cases, the scheduler tries
> to get the current kernel time, trying to get xtime_lock (which results
> in a deadlock).  This moved the printks outside of the lock.  It also
> adds a comment to not use printk while holding xtime_lock.
>
> Signed-off-by: Chris Adams <cmadams@hiwaay.net>

Acked-by: Linas Vepstas <linasvepstas@gmail.com>

BTW, I audited the other code in kernel/time/*.c and it looks like there
are no other printk's under the lock. Not surprising -- if there were,
they'd have been found by now. Indeed, in timekeeping.c line 198,
it seems that someone else had indeed tripped over this :-P

--linas
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