Re: [PATCH] arp_queue: serializing unlink + kfree_skb

David S. Miller wrote:

Absolutely, I agree.  My fingers even itched as I typed those lines
in.  I didn't change the wording because I couldn't come up with
anything better.

How about something like:

  Unlike the above routines, atomic_???_return are required to perform
  memory barriers [...]

I think "implicit" and "explicit" here are just confusing, because
you don't define them, and there's no intuitively correct meaning
either.

Perhaps a little warning could also be useful for the reader who
wasn't paying close attention to whose role is described:

  Note: this means that a caller of atomic_add, etc., who needs a
  memory barrier before or after that call has to code the memory
  barrier explicitly, whereas a caller of atomic_???_return can rely
  on said functions to provide the barrier without further ado. For
  the implementor of the atomic functions, the roles are reversed.

You still get the memory barrier, whether you read the return
value or not.

That might be something worth mentioning. Not that a construct
is used that gcc can optimize away when nobody cares about the
return value.

- Werner

-- 
  _________________________________________________________________________
 / Werner Almesberger, Buenos Aires, Argentina         wa@almesberger.net /
/_http://www.almesberger.net/____________________________________________/