From: Frederic Weisbecker <fweisbec@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>, LKML <linux-kernel@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH] lockdep: Make lockstats counting per cpu
Date: Fri, 26 Mar 2010 18:43:20 +0100 [thread overview]
Message-ID: <20100326174318.GF5188@nowhere> (raw)
In-Reply-To: <1269589714.12097.122.camel@laptop>
On Fri, Mar 26, 2010 at 08:48:34AM +0100, Peter Zijlstra wrote:
> On Fri, 2010-03-26 at 07:52 +0100, Peter Zijlstra wrote:
> > On Fri, 2010-03-26 at 03:22 +0100, Frederic Weisbecker wrote:
> > > We can't use irqsafe per cpu counters for that as
> > > these stats might be also written from NMI path, and irqsafe per
> > > cpu counters are not NMI safe, but local_t operations are.
> > >
> > lockdep shouldn't do NMI, nmi_enter() has an explicit lockdep_off().
>
> Also, more importantly, you simply should never use locks in NMI context
> to begin with ;-)
Right. I just thought ther could be some path that use rcu_read_lock
things there or whatever check. I mean, NMI don't need rcu_read_lock
but it could call helpers that use it.
Whatever, lockdep is off there. Looks like I can safely use per cpu counters.
next prev parent reply other threads:[~2010-03-26 17:43 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-26 2:22 [PATCH] lockdep: Make lockstats counting per cpu Frederic Weisbecker
2010-03-26 3:11 ` Frederic Weisbecker
2010-03-26 3:13 ` Frederic Weisbecker
2010-03-26 9:16 ` Ingo Molnar
2010-03-26 17:11 ` Frederic Weisbecker
2010-03-26 6:52 ` Peter Zijlstra
2010-03-26 7:48 ` Peter Zijlstra
2010-03-26 17:43 ` Frederic Weisbecker [this message]
2010-03-26 17:39 ` Frederic Weisbecker
-- strict thread matches above, loose matches on Subject: below --
2010-03-28 0:29 [PATCH v3] " Frederic Weisbecker
2010-04-05 22:10 ` [PATCH] " Frederic Weisbecker
2010-04-06 8:46 ` Peter Zijlstra
2010-04-06 9:24 ` Frederic Weisbecker
2010-04-06 9:25 ` Frederic Weisbecker
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