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From: Andrew Morton <akpm@linux-foundation.org>
To: Yury Polyanskiy <ypolyans@princeton.edu>
Cc: Joel Becker <joel.becker@oracle.com>,
	linux-kernel@vger.kernel.org, john stultz <johnstul@us.ibm.com>,
	Jan Glauber <jan.glauber@de.ibm.com>
Subject: Re: [PATCH] hangcheck-timer is broken on x86
Date: Fri, 26 Mar 2010 14:24:23 -0700	[thread overview]
Message-ID: <20100326142423.1334d407.akpm@linux-foundation.org> (raw)
In-Reply-To: <20100323233611.6dcbe4f4@penta.localdomain>

On Tue, 23 Mar 2010 23:36:11 -0400
Yury Polyanskiy <ypolyans@princeton.edu> wrote:

> The drivers/char/hangcheck-timer.c is doubly broken. First, the
> following line overflows unsigned long:
> # define TIMER_FREQ (HZ*loops_per_jiffy)
> 
> Second, and more importantly, loops_per_jiffy has little to do with the conversion from the
> the time scale of get_cycles() (aka rdtsc) to the time scale of jiffies.

It's a bit odd to have a driver be this broken on x86_32 for five years
without anyone noticing.  What are the user-visible effects of these
shortcomings?

Also, please do send us a Signed-off-by: for this patch, as explained
in Documentation/SubmittingPatches, thanks.


  reply	other threads:[~2010-03-26 21:24 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-03-24  3:36 [PATCH] hangcheck-timer is broken on x86 Yury Polyanskiy
2010-03-26 21:24 ` Andrew Morton [this message]
2010-03-26 21:52   ` Yury Polyanskiy
2010-03-26 21:46 ` Joel Becker
2010-03-26 22:00   ` Yury Polyanskiy
2010-03-27  0:57     ` Joel Becker
2010-03-27  2:02       ` Yury Polyanskiy
2010-03-27 22:03         ` Joel Becker
2010-03-27 22:51           ` Yury Polyanskiy
2010-03-27 23:36             ` Joel Becker
2010-03-28  2:08               ` Yury Polyanskiy
2010-03-29  1:00   ` john stultz
2010-03-29 14:11     ` Yury Polyanskiy
2010-03-29 16:43       ` john stultz
2010-03-29 17:04         ` Yury Polyanskiy
2010-03-29 18:44           ` john stultz
2010-03-29 19:53             ` Joel Becker
2010-03-29 21:08             ` Yury Polyanskiy
2010-03-29 21:43               ` john stultz
2010-03-29 22:34                 ` Yury Polyanskiy
2010-04-08  0:52                   ` Joel Becker

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