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

From: Ingo Molnar
Date: Mon Jul 30 2007 - 05:22:34 EST



* Daniel Walker <dwalker@xxxxxxxxxx> 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.

Ingo
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