Messages in this thread | | | Subject | Re: [RFC] block: change to use atomic_inc_return_release() | From | Jens Axboe <> | Date | Mon, 16 Nov 2015 20:38:36 -0700 |
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On 11/16/2015 08:24 PM, yalin wang wrote: > Some arch define this atomic_inc_return_release() OP.
That is a very vague commit message, you'll need a whole lot more than that... A commit message is supposed to describe the reason for the change. You provide no reason for the change.
> diff --git a/block/bio.c b/block/bio.c > index fbc558b..b251857 100644 > --- a/block/bio.c > +++ b/block/bio.c > @@ -310,8 +310,7 @@ static void bio_chain_endio(struct bio *bio, int error) > static inline void bio_inc_remaining(struct bio *bio) > { > bio->bi_flags |= (1 << BIO_CHAIN); > - smp_mb__before_atomic(); > - atomic_inc(&bio->__bi_remaining); > + atomic_inc_return_release(&bio->__bi_remaining);
Are these equivalent? Where's the documentation for this primitive? The previous code ensured that we ordered the dec of the remaining count with the update of the flags.
-- Jens Axboe
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