From: Oleg Nesterov <oleg@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Anton Arapov <anton@redhat.com>, Ingo Molnar <mingo@elte.hu>,
Linus Torvalds <torvalds@linux-foundation.org>,
Michal Marek <mmarek@suse.cz>,
Mikulas Patocka <mpatocka@redhat.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Peter Zijlstra <peterz@infradead.org>,
Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH -mm 0/3] percpu_rw_semaphore: lockdep + config
Date: Sun, 18 Nov 2012 20:02:57 +0100 [thread overview]
Message-ID: <20121118190257.GA9660@redhat.com> (raw)
On 11/11, Oleg Nesterov wrote:
>
> To remind, once/if I am sure you agree with this patch I'll send 2 additional
> and simple patches:
>
> 1. lockdep annotations
>
> 2. CONFIG_PERCPU_RWSEM
It turns out, lockdep annotations are not that simple due to internal
locks used by percpu_rw_semaphore. To clarify, it is actually simple
but lockdep_set_novalidate_class() doesn't seem to actually work, and
more importantly, it must not be used according to checkpatch.pl. And
I guess ->lockdep_recursion should not be used too.
However, without some tricks, the output from lockdep (when it finds
the problem) does not look very clear because it blames those internal
locks instead of "the whole" percpu_rw_semaphore.
So this series starts with the small optimization which I was going to
do later. It removes ->writer_mutex and greatly simplifies 2/3.
Oleg.
next reply other threads:[~2012-11-18 19:02 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-18 19:02 Oleg Nesterov [this message]
2012-11-18 19:03 ` [PATCH 1/3] percpu_rw_semaphore: kill ->writer_mutex, add ->write_ctr Oleg Nesterov
2012-11-18 19:03 ` [PATCH 2/3] percpu_rw_semaphore: add the lockdep annotations Oleg Nesterov
2012-11-19 23:05 ` Andrew Morton
2012-11-20 16:31 ` Oleg Nesterov
2012-11-18 19:03 ` [PATCH 3/3] percpu_rw_semaphore: introduce CONFIG_PERCPU_RWSEM Oleg Nesterov
2012-11-19 13:54 ` Q: __lockdep_no_validate__ (Was: [PATCH -mm 0/3] percpu_rw_semaphore: lockdep + config) Oleg Nesterov
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