Re: [PATCH] markers: bit-field is not thread-safe nor smp-safe

[Mathieu Desnoyers]

* Lai Jiangshan (laijs@xxxxxxxxxxxxxx) wrote:
> 
> bit-field is not thread-safe nor smp-safe.
> 
> struct marker_entry.rcu_pending is not protected by any lock
> in rcu-callback free_old_closure().
> so we must turn it into a safe type.
> 

All struct marker_entry.rcu_pending accesses are done with the
markers_mutex held, except the one done in free_old_closure(). Normally,
there should be a 
        if (entry->rcu_pending)
           rcu_barrier_sched();

At the beginning of each markers_mutex section (just after get_marker())
to make sure any pending callback is executed at that point before any
of rcu_pending or ptype are touched.

I just noticed that the "markers: fix unchecked format" patch has a race
with respect to this. I'll post a patch in a jiffy.

Mathieu

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Mathieu Desnoyers
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