From: Rusty Russell <rusty@rustcorp.com.au>
To: Andi Kleen <andi@firstfloor.org>
Cc: linux-kernel@vger.kernel.org, Andi Kleen <ak@linux.intel.com>,
paulmck@linux.vnet.ibm.com, tglx@linutronix.de
Subject: Re: [PATCH] Convert preempt_disabled in module.c to rcu read lock
Date: Thu, 23 Sep 2010 10:37:08 +0930 [thread overview]
Message-ID: <201009231037.09417.rusty@rustcorp.com.au> (raw)
In-Reply-To: <1285160840-16506-1-git-send-email-andi@firstfloor.org>
On Wed, 22 Sep 2010 10:37:20 pm Andi Kleen wrote:
> From: Andi Kleen <ak@linux.intel.com>
>
> Thomas Gleixner pointed out that the list_for_each_rcu()
> in module really need to use RCU read lock, not preempt disable.
> This is especially needed for the preemptive RCU code.
> >From what I understand the only reason for the preemption
> disabling is to protect against rcu, so using rcu_read_lock()
> is correct.
The preempt_disable() also protects against stop_machine() on
module remove.
I haven't been following the RCU story, but we were always slightly
abusing the infrastructure here just to do lockless insert. If
list_for_each_entry_rcu() is changing, perhaps we need to open-code
the old version here?
Rusty.
next prev parent reply other threads:[~2010-09-23 4:34 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-22 13:07 [PATCH] Convert preempt_disabled in module.c to rcu read lock Andi Kleen
2010-09-23 1:07 ` Rusty Russell [this message]
2010-09-23 17:02 ` Paul E. McKenney
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