RE: [PATCH 04/12] bcache: Don't reinvent the wheel but use existing llist API

박병철/선임연구원/SW Platform(연)AOT팀(byungchul.park@lge.com)
2017-09-26T06:39:45Z

> -----Original Message-----
> From: Michael Lyle [mailto:mlyle@lyle.org]
> Sent: Tuesday, September 26, 2017 1:38 PM
> To: Coly Li
> Cc: linux-bcache@vger.kernel.org; linux-block@vger.kernel.org;
> axboe@kernel.dk; Eric Wheeler; Byungchul Park; Kent Overstreet
> Subject: Re: [PATCH 04/12] bcache: Don't reinvent the wheel but use existing
> llist API
>
> I believe this introduces a critical bug.
>
> cl->list is used to link together the llists for both things waiting,
> and for things that are being woken.
>
> If a closure that is woken decides to wait again, it will corrupt the
> llist that __closure_wake_up is using.
>
> The previous iteration structure gets the next element of the list
> before waking and is therefore safe.

Do you mean we have to use llist_for_each_entry_safe() instead of non-safe version?
Is it ok if we use it instead?

> Mike