From: Thomas Gleixner <tglx@linutronix.de>
To: Linus Torvalds <torvalds@osdl.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Dave Jones <davej@redhat.com>, Andrew Morton <akpm@osdl.org>,
john stultz <johnstul@us.ibm.com>, Ingo Molnar <mingo@elte.hu>,
Stable Team <stable@kernel.org>,
"Fortier,Vincent [Montreal]" <Vincent.Fortier1@EC.GC.CA>
Subject: Re: [PATCH] NTP: remove clock_was_set() call to prevent deadlock
Date: Tue, 03 Jul 2007 21:56:30 +0200 [thread overview]
Message-ID: <1183492590.3291.39.camel@chaos> (raw)
In-Reply-To: <1183485920.3291.28.camel@chaos>
On Tue, 2007-07-03 at 20:05 +0200, Thomas Gleixner wrote:
> The clock_was_set() call in seconds_overflow() which happens only when
> leap seconds are inserted / deleted is wrong in two aspects:
>
> 1. it results in a call to on_each_cpu() with interrupts disabled
> 2. it is potential deadlock source vs. call_lock in smp_call_function()
>
> The only possible side effect of the removal might be, that an absolute
> CLOCK_REALTIME timer fires 1 second too late, in the rare case of leap
> second deletion and an absolute CLOCK_REALTIME timer which expires in
> the affected time frame. It will never fire too early.
>
> This was probably observed by the reporter of a June 30th -> July 1st
> hang: http://lkml.org/lkml/2007/7/3/
Ooops, missed the full reference:
http://lkml.org/lkml/2007/7/3/103
tglx
next prev parent reply other threads:[~2007-07-03 19:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-03 18:05 [PATCH] NTP: remove clock_was_set() call to prevent deadlock Thomas Gleixner
2007-07-03 19:41 ` Ingo Molnar
2007-07-03 19:56 ` Thomas Gleixner [this message]
2007-07-04 11:06 ` Roman Zippel
2007-07-04 11:15 ` Thomas Gleixner
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