From: Andrew Morton <akpm@osdl.org>
To: dipankar@in.ibm.com
Cc: linux-kernel@vger.kernel.org,
Paul E McKenney <paulmck@us.ibm.com>, Ingo Molnar <mingo@elte.hu>
Subject: Re: [-mm PATCH] RCU: debug sleep check
Date: Sun, 24 Sep 2006 14:44:40 -0700 [thread overview]
Message-ID: <20060924144440.ca7e6464.akpm@osdl.org> (raw)
In-Reply-To: <20060924213508.GG13432@in.ibm.com>
On Mon, 25 Sep 2006 03:05:08 +0530
Dipankar Sarma <dipankar@in.ibm.com> wrote:
> On Sun, Sep 24, 2006 at 11:56:46AM -0700, Andrew Morton wrote:
> > On Mon, 25 Sep 2006 00:05:09 +0530
> > Dipankar Sarma <dipankar@in.ibm.com> wrote:
> >
> > > Add a debug check for rcu read-side critical section code calling
> > > a function that might sleep which is illegal. The check is enabled only
> > > if CONFIG_DEBUG_SPINLOCK_SLEEP is set.
> > >
> >
> > Does this actually change anything? rcu_read_lock is preempt_disable(), and
> > might_sleep() already triggers if called inside preempt_disable().
>
> It makes a difference if CONFIG_PREEMPT=n. AFAICS, preempt_disable()
> is a nop then and rcu needs its own check for sleeping while
> in read-side critical section.
Right. I think enough people run with CONFIG_PREEMPT=y to make this
change rather unnecessary.
And if there are developers out there who are testing their code without an
effective CONFIG_DEBUG_SPINLOCK_SLEEP, then *that* is what we need to fix,
no?
next prev parent reply other threads:[~2006-09-24 21:44 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-09-23 15:29 [-mm PATCH] RCU: various patches Dipankar Sarma
2006-09-23 15:31 ` [-mm PATCH 1/4] RCU: split classic rcu Dipankar Sarma
2006-09-25 16:54 ` Christoph Hellwig
2006-09-27 16:32 ` Paul E. McKenney
2006-09-28 14:26 ` Christoph Hellwig
2006-09-28 14:44 ` Dipankar Sarma
2006-09-23 15:34 ` [-mm PATCH 2/4]RCU: softirq for RCU Dipankar Sarma
2006-09-23 15:35 ` [-mm PATCH 3/4] RCU: preemptible RCU Dipankar Sarma
2006-09-23 15:36 ` [-mm PATCH 4/4] RCU: preempt rcu trace Dipankar Sarma
2006-09-23 18:56 ` [-mm PATCH] RCU: various patches Dipankar Sarma
2006-09-24 3:01 ` Dipankar Sarma
2006-09-24 14:38 ` Dipankar Sarma
2006-09-24 18:35 ` [-mm PATCH] RCU: debug sleep check Dipankar Sarma
2006-09-24 18:56 ` Andrew Morton
2006-09-24 21:35 ` Dipankar Sarma
2006-09-24 21:44 ` Andrew Morton [this message]
2006-09-24 21:58 ` Dipankar Sarma
2006-09-25 18:08 ` Paul E. McKenney
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