> -----Original Message----- > From: Coly Li [mailto:i@xxxxxxx] > Sent: Tuesday, September 26, 2017 4:09 PM > To: 박병철/선임연구원/SW Platform(연)AOT팀(byungchul.park@xxxxxxx); > Michael Lyle; Coly Li > Cc: linux-bcache@xxxxxxxxxxxxxxx; linux-block@xxxxxxxxxxxxxxx; > axboe@xxxxxxxxx; Eric Wheeler; Kent Overstreet; kernel-team@xxxxxxx > Subject: Re: [PATCH 04/12] bcache: Don't reinvent the wheel but use existing > llist API > > On 2017/9/26 下午2:39, 박병철/선임연구원/SW > Platform(연)AOT팀(byungchul.park@xxxxxxx) wrote: > >> -----Original Message----- > >> From: Michael Lyle [mailto:mlyle@xxxxxxxx] > >> Sent: Tuesday, September 26, 2017 1:38 PM > >> To: Coly Li > >> Cc: linux-bcache@xxxxxxxxxxxxxxx; linux-block@xxxxxxxxxxxxxxx; > >> axboe@xxxxxxxxx; 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? > > Yes, we should use llist_for_each_entry_safe(), there is a quite > implicit race here. Hi coly, As you know, my first patch used the safe version, but you suggested to replace It with non-safe one. :( I will change it so it does the same as the original patch did. :) Thank you very much, Byungchul > -- > Coly Li
