From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: paulmck@linux.vnet.ibm.com
Cc: Peter Zijlstra <peterz@infradead.org>,
linux-arch@vger.kernel.org,
linux-kernel <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: current_thread_info() vs task_thread_info(current)
Date: Tue, 19 Jul 2011 10:57:37 +1000 [thread overview]
Message-ID: <1311037057.25044.346.camel@pasglop> (raw)
In-Reply-To: <20110719003930.GF2312@linux.vnet.ibm.com>
On Mon, 2011-07-18 at 17:39 -0700, Paul E. McKenney wrote:
> > Hrm, no I don't see that happening no. The preempt count when
> exiting an
> > irq or softirq stack should be the exact same as when entering it,
> which
> > is why we don't bother copying it over. Do you see any case where
> that
> > wouldn't hold ?
>
> Nope, other than seeing preempt_count() transition from zero to three
> across a spin_unlock_irqrestore() for no good reason that I could see.
Do you have a nice repro-case ? :-)
That sounds really nasty ... smells really like something bad's
happening from an interrupt, but we don't copy back the preempt-count
from the interrupt stacks at all, so that's really really odd.
Cheers,
Ben.
next prev parent reply other threads:[~2011-07-19 0:57 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-18 11:23 current_thread_info() vs task_thread_info(current) Peter Zijlstra
2011-07-18 11:36 ` Gleb Natapov
2011-07-18 11:44 ` Peter Zijlstra
2011-07-18 11:48 ` Gleb Natapov
2011-07-18 11:54 ` Benjamin Herrenschmidt
2011-07-18 14:37 ` Paul E. McKenney
2011-07-18 21:36 ` Benjamin Herrenschmidt
2011-07-18 21:36 ` Benjamin Herrenschmidt
2011-07-19 0:39 ` Paul E. McKenney
2011-07-19 0:57 ` Benjamin Herrenschmidt [this message]
2011-07-19 0:57 ` Benjamin Herrenschmidt
2011-07-19 3:04 ` Paul E. McKenney
2011-07-19 3:46 ` Paul E. McKenney
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