From: Daniel Walker <dwalker@mvista.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org
Subject: Re: [PATCH -rt 1/9] preempt rcu: check for underflow
Date: Mon, 30 Jul 2007 08:48:48 -0700 [thread overview]
Message-ID: <1185810528.2636.17.camel@imap.mvista.com> (raw)
In-Reply-To: <20070730092211.GA25640@elte.hu>
On Mon, 2007-07-30 at 11:22 +0200, Ingo Molnar wrote:
> * Daniel Walker <dwalker@mvista.com> wrote:
>
> > + /*
> > + * If our rcu_read_lock_nesting went negative, likely
> > + * something is wrong..
> > + */
> > + WARN_ON(current->rcu_read_lock_nesting < 0);
>
> have you actually caught any rcu locking problem this way? Double
> unlocks should be caught by lockdep already, at a higher level.
>
> in any case i've added a slightly different form of this change to the
> -rt queue that will also check for counter overflows. But i'm not sure
> we want to litter the code with trivial checks like this, so i'm keeping
> it separate and if it does not trigger anything real i'll remove it.
I haven't caught anything with it, but this code would have made it much
easier to catch the single rcu unlock in sys_sched_yield() which was
silent in PREEMPT_RT, and hung !PREEMPT_RT ..
It's fine with me, if you have another method.
Daniel
prev parent reply other threads:[~2007-07-30 15:59 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-30 2:45 Daniel Walker
2007-07-30 2:45 ` [PATCH -rt 2/9] Dont allow non-threaded softirqs and threaded hardirqs Daniel Walker
2007-07-30 9:23 ` Ingo Molnar
2007-07-30 11:28 ` Steven Rostedt
2007-07-30 2:45 ` [PATCH -rt 3/9] Fix jiffies wrap issue in update_times Daniel Walker
2007-07-30 9:25 ` Ingo Molnar
2007-07-30 2:45 ` [PATCH -rt 4/9] ifdef raise_softirq_irqoff wakeup Daniel Walker
2007-07-30 9:27 ` Ingo Molnar
2007-07-30 15:48 ` Daniel Walker
2007-08-06 7:20 ` Ingo Molnar
2007-07-30 2:45 ` [PATCH -rt 5/9] net: fix mis-merge in qdisc_restart Daniel Walker
2007-07-30 9:30 ` Ingo Molnar
2007-07-30 2:45 ` [PATCH -rt 6/9] spinlock/rt_lock random cleanups Daniel Walker
2007-07-30 4:58 ` Ankita Garg
2007-07-30 15:48 ` Daniel Walker
2007-07-30 9:31 ` Ingo Molnar
2007-07-30 2:45 ` [PATCH -rt 7/9] introduce PICK_FUNCTION Daniel Walker
2007-07-30 9:39 ` Peter Zijlstra
2007-07-30 16:16 ` Daniel Walker
2007-07-30 2:45 ` [PATCH -rt 8/9] spinlocks/rwlocks: use PICK_FUNCTION() Daniel Walker
2007-07-30 2:45 ` [PATCH -rt 9/9] seqlocks: use PICK_FUNCTION Daniel Walker
2007-08-06 7:21 ` Ingo Molnar
2007-08-08 19:40 ` Daniel Walker
2007-07-30 5:26 ` [PATCH -rt 1/9] preempt rcu: check for underflow Paul E. McKenney
2007-07-30 9:22 ` Ingo Molnar
2007-07-30 15:48 ` Daniel Walker [this message]
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