On 2017/9/26 下午3:16, 박병철/선임연구원/SW
Platform(연)AOT팀(byungchul.park@lge.com) wrote:

quoted

-----Original Message-----
From: Coly Li [mailto:i@coly.li]
Sent: Tuesday, September 26, 2017 4:09 PM
To: Michael Lyle; 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

On 2017/9/26 下午12:38, Michael Lyle wrote:

quoted

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.

Hi Mike,

Good catch! I see llist_del_all() but forget cl->list can be modified in
closure_wait(). Yes there is potential chance to mislead
llist_for_each_entry() to iterate wrong list.
llist_for_each_entry_safe() should be used here. I will send a fix to
Jens, hope to catch up 4.14 still.

I see. You have a plan to do it. Please fix it.

Oh, I just see this email, when I replied your last one.
Sure, let me fix my fault.

-- 
Coly Li