On 09/28/2017 11:44 PM, Linus Torvalds wrote: > 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. It is documented though, but maybe not well enough... I've actually had to document/explain it enough times now, that it might be worth making a general construct. Though it has to be used carefully, so perhaps it's better contained as separate use cases. -- Jens Axboe
