From: David Miller <davem@davemloft.net>
To: a.p.zijlstra@chello.nl
Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, ego@in.ibm.com,
hugh@veritas.com, dada1@cosmosbay.com
Subject: Re: [PATCH 2/2] lockdep: fix fib_hash softirq inversion
Date: Wed, 12 Mar 2008 23:08:43 -0700 (PDT) [thread overview]
Message-ID: <20080312.230843.114525346.davem@davemloft.net> (raw)
In-Reply-To: <20080312121323.959513000@chello.nl>
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Wed, 12 Mar 2008 13:09:22 +0100
> =========================================================
> [ INFO: possible irq lock inversion dependency detected ]
> 2.6.25-rc4-sched-devel.git #56
> ---------------------------------------------------------
> swapper/0 just changed the state of lock:
> (&rt_hash_locks[i]){-+..}, at: [<ffffffff804721ac>] rt_intern_hash+0x8c/0x3b0
> but this lock took another, soft-read-irq-unsafe lock in the past:
> (fib_hash_lock){-.-?}
>
> and interrupts could create inverse lock ordering between them.
I tried to figure out what lockdep doesn't like here.
Could you show me the specific code path that could cause
the lock conflict?
Adding BH disabling to fib_hash_lock will add non-trivial
costs to these code paths, so I'd like to avoid this if
possible.
next prev parent reply other threads:[~2008-03-13 6:08 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-12 12:09 [PATCH 0/2] lockdep vs recursive read locks Peter Zijlstra
2008-03-12 12:09 ` [PATCH 1/2] lockdep: fix recursive read lock validation Peter Zijlstra
2008-03-12 20:26 ` Gautham R Shenoy
2008-03-12 12:09 ` [PATCH 2/2] lockdep: fix fib_hash softirq inversion Peter Zijlstra
2008-03-13 3:50 ` [PATCH] net/lockdep: Make nl_table_lock read acquire softirq safe Gautham R Shenoy
2008-03-13 6:08 ` David Miller [this message]
2008-03-13 9:40 ` [PATCH 2/2] lockdep: fix fib_hash softirq inversion Arjan van de Ven
2008-03-13 11:25 ` [PATCH 0/2] lockdep vs recursive read locks Hugh Dickins
2008-03-14 7:35 ` Peter Zijlstra
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