Re: atomic_dec_and_test for child dst needed in dst_destroy?

["David S. Miller" <davem@xxxxxxxxxxxxx>]

On Wed, 06 Apr 2005 18:32:54 +1000
Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> wrote:

> In fact, the atomic_dec_and_test is really only needed for unhashed
> entries (i.e., IPsec).  So we could do something like this so that
> all hashed entries undergo atomic_dec.
> 
> This would only make sense if there were architectures where
> atomic_dec is significantly cheaper compared to atomic_dec_and_test.
> 
> Do such beasts exist?

See his other emails in this thread.  If it can be converted to
atomic_dec() then he wants to change the counter into an array
of counters on NUMA systems.

But his trick only works if the atomic_dec_and_test() can be eliminated
for all cases, which we're now quite certain is not possible.