Re: [PATCH] arp_queue: serializing unlink + kfree_skb

Werner Almesberger
2005-02-11T04:29:19Z

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

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