Re: [PATCH 10/12] writeback: only allow one inflight and pending full flush

[Linus Torvalds]

On Thu, Sep 28, 2017 at 2:41 PM, Andrew Morton
<akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> test_and_set_bit()?

If there aren't any atomicity concerns (either because of higher-level
locking, or because racing and having two people set the bit is fine),
it can be better to do them separately if the test_bit() is the common
case and you can avoid dirtying a cacheline that way.

But yeah, if that is the case, it might be worth documenting, because
test_and_set_bit() is the more obviously appropriate "there can be
only one" model.

               Linus