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Date: Tue, 29 Apr 2008 15:16:52 +0200
From: "Bart Van Assche" <bart.vanassche@gmail.com>
To: ego@in.ibm.com
Subject: Re: [PATCH 1/8] lockdep: fix recursive read lock validation
Cc: linux-kernel@vger.kernel.org, "Zdenek Kabelac" <zdenek.kabelac@gmail.com>,
       "Peter Zijlstra" <a.p.zijlstra@chello.nl>,
       "Oleg Nesterov" <oleg@tv-sign.ru>,
       "Heiko Carstens" <heiko.carstens@de.ibm.com>,
       "Rafael J. Wysocki" <rjw@sisk.pl>,
       "Andrew Morton" <akpm@linux-foundation.org>,
       "Ingo Molnar" <mingo@elte.hu>, "Srivatsa Vaddagiri" <vatsa@in.ibm.com>
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On Tue, Apr 29, 2008 at 2:57 PM, Gautham R Shenoy <ego@in.ibm.com> wrote:
> Subject: lockdep: fix recursive read lock validation
>  This means that the following sequence is now invalid, whereas previously
>  it was considered valid:
>
>   rlock(a); rlock(b); runlock(b); runlock(a)
>   rlock(b); rlock(a);

Why are you marking this sequence as invalid ? Although it can be
debated whether it is good programming practice to be inconsistent
about the order of read-locking, the above sequence can't be involved
in a deadlock.

Bart.