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Subject: Re: [PATCH] atomic: add atomic_inc_not_zero_hint()
From: Eric Dumazet <eric.dumazet@gmail.com>
To: paulmck@linux.vnet.ibm.com
Cc: Andrew Morton <akpm@linux-foundation.org>,
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        Nick Piggin <npiggin@kernel.dk>
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Date: Fri, 05 Nov 2010 20:12:51 +0100
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Le vendredi 05 novembre 2010 à 11:40 -0700, Paul E. McKenney a écrit :

> OK, so I cannot resist the challenge...  ;-)
> 

I knew that ;)

> Suppose that the atomic_inc_not_zero_hint() is in common code that might
> be invoked from a cleanup path.  On the cleanup path, perhaps within an
> RCU callback, if the reference is zero, we have the only reference and
> thus don't need to increment the reference count.  On the other hand,
> if the reference is non-zero, we want to obtain a reference in order
> to safely attempt to encourage the other reference holder to let go
> more quickly.
> 
> Perhaps a bit of a stretch, but why not just replace the above
> "return 0" with "atomic_inc_not_zero(v)"?  It will usually be
> compiled out, right?

Yes indeed, thanks !