Re: [PATCH -rt 1/9] preempt rcu: check for underflow

["Paul E. McKenney" <paulmck@linux.vnet.ibm.com>]

On Sun, Jul 29, 2007 at 07:45:35PM -0700, Daniel Walker wrote:
> Simple WARN_ON to catch any underflow in rcu_read_lock_nesting.
> 
> Signed-off-by: Daniel Walker <dwalker@mvista.com>

Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

> ---
>  kernel/rcupreempt.c |    6 ++++++
>  1 file changed, 6 insertions(+)
> 
> Index: linux-2.6.22/kernel/rcupreempt.c
> ===================================================================
> --- linux-2.6.22.orig/kernel/rcupreempt.c
> +++ linux-2.6.22/kernel/rcupreempt.c
> @@ -157,6 +157,12 @@ void __rcu_read_unlock(void)
>  	}
> 
>  	local_irq_restore(oldirq);
> +
> +	/*
> +	 * If our rcu_read_lock_nesting went negative, likely
> +	 * something is wrong..
> +	 */
> +	WARN_ON(current->rcu_read_lock_nesting < 0);
>  }
> 
>  static void __rcu_advance_callbacks(void)
> 
> -- 
> -
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