On Wed, Jun 17, 2015 at 11:41:14AM +0200, Ingo Molnar wrote:
>
> * Andy Lutomirski <l...@kernel.org> wrote:
>
> > This will let us sprinkle sanity checks around the kernel without
> > making too much of a mess.
> >
> > Signed-off-by: Andy Lutomirski <l...@kernel.org>
> > ---
> > include/linux/context_tracking.h | 8 ++++++++
> > 1 file changed, 8 insertions(+)
> >
> > diff --git a/include/linux/context_tracking.h
> > b/include/linux/context_tracking.h
> > index 2821838256b4..0fbea4b152e1 100644
> > --- a/include/linux/context_tracking.h
> > +++ b/include/linux/context_tracking.h
> > @@ -57,6 +57,13 @@ static inline void context_tracking_task_switch(struct
> > task_struct *prev,
> > if (context_tracking_is_enabled())
> > __context_tracking_task_switch(prev, next);
> > }
> > +
> > +static inline void context_tracking_assert_state(enum ctx_state state)
> > +{
> > + rcu_lockdep_assert(!context_tracking_is_enabled() ||
> > + this_cpu_read(context_tracking.state) == state,
> > + "context tracking state was wrong");
> > +}
>
> Please don't introduce assert() style debug check interfaces!
>
> (And RCU should be fixed too I suspect.)
The thought is to rename rcu_lockdep_assert() to RCU_LOCKDEP_WARN()
by analogy to WARN()? Easy to do if so! Or am I missing the point?
Thanx, Paul
> They are absolutely horrible on the brain when mixed with WARN_ON()
> interfaces,
> which are the dominant runtime check interface in the kernel.
>
> Instead make it something like:
>
> #define ct_state() (this_cpu_read(context_tracking.state))
>
> #define CT_WARN_ON(cond) \
> WARN_ON(context_tracking_is_enabled() && (cond))
>
> and then the debug checks can be written as:
>
> CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
>
> This is IMHO _far_ more readable than:
>
> context_tracking_assert_state(CONTEXT_KERNEL);
>
> ok?
>
> (Assuming people will accept 'ct/CT' as an abbreviation for context tracking.)
>
> Thanks,
>
> Ingo
>
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