From mboxrd@z Thu Jan  1 00:00:00 1970
From: bhat.srivatsa@gmail.com (Srivatsa Bhat)
Date: Mon, 29 Oct 2012 00:03:08 +0530
Subject: Tools for checking incorrect usage of locking techniques in
	k-space
In-Reply-To: <20121027190656.GA5395@gmail.com>
References: <20121027044145.GA13155@gmail.com>
	<CAC_BnSUuoQhqB77c024__Pm2mOY25rYVbvyR33BECqjoZNwh3w@mail.gmail.com>
	<20121027190656.GA5395@gmail.com>
Message-ID: <CAC_BnSU8mXeEig9wPVNrX8oU9kLS9A=KbF7RgNXpyntMDKy15A@mail.gmail.com>
To: kernelnewbies@lists.kernelnewbies.org
List-Id: kernelnewbies.lists.kernelnewbies.org

Hi,

On Sun, Oct 28, 2012 at 12:36 AM, Kumar amit mehta <gmate.amit@gmail.com> wrote:
> Thank you Srivatsa. It seems that lockdep framework is enabled on my running
> kernel.
>
> <snip>
> amit at ubuntu:/boot$ egrep -i "debug_kernel|lockdep" config-3.2.0-29-generic-pae
> CONFIG_LOCKDEP_SUPPORT=y
> CONFIG_DEBUG_KERNEL=y

You'll need CONFIG_LOCKDEP=y as well. An easy way to configure lock debugging
checks is to run 'make menuconfig' and enable the required options under the
"Kernel hacking" section.

Regards,
Srivatsa S. Bhat

> <snip>
>
> If above configuration is all that I need, then should I be seeing warning/error
> messages in kernel logs(/var/log/kern.log) when there is inconsistency in
> locking ? To test my hypothesis, I modified my simple kernel module to
> deliberately induce locking error (After initializing read-write semaphore, I call
> down_write() and do not free this semaphore lock by commenting out up_write()
> invocation). But still I don't see any error or warning message trace in kernel
> logs, I think, I'm missing something.