Re: BUG: tracer_alloc_buffers returned with preemption imbalance

[Fengguang Wu <fengguang.wu@intel.com>]

> >  static inline int rcu_blocking_is_gp(void)
> >  {
> >         might_sleep();  /* Check for RCU read-side critical section. */
> > +       preempt_disable();
> >         return num_online_cpus() <= 1;
> > +       preempt_enable();
> >  }
> 
> Thank you!  I have no idea how a preempt_disable() causes that badness
> to happen, but this commit is not yet critically important, so I will
> drop it.

preempt_enable() becomes dead code because of the return statement?
I wonder why gcc didn't issue a warning (or I failed to catch it)...

Thanks,
Fengguang