Re: [PATCH] percpu_counter: use local_t and atomic_long_t if possible

[Rusty Russell]

On Tuesday 23 December 2008 22:13:21 Peter Zijlstra wrote:
> One think that sprung to mind,..
> 
> IFF we're going to implement percpu_counter with local_t and make
> local_t this funny tri-counter thing which has its own error, you need
> to fix up bdi_stat_error() - it expects to be an upper bound for the
> counter error, getting that wrong _will_ cause deadlocks.

It's OK: local_add_return() can't have error; that's why the trival
implementation disables interrupts around it.

Hope that helps,
Rusty.
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