Li Zefan wrote: > Bill Davidsen wrote: > >> Li Zefan wrote: >> >>> Liu Aleaxander wrote: >>> >>>> From: Liu Aleaxander <Aleaxander@xxxxxxxxx> >>>> Date: Wed, 4 Nov 2009 09:27:06 +0800 >>>> Subject: [PATCH] Fixes the un-paired cgroup lock problem >>>> >>>> In cgroup_lock_live_group, it locks the cgroup by mutex_lock, while >>>> in the >>>> cgroup_tasks_write, it unlock it by cgroup_unlock. Even though they are >>>> equal, but I do think we should make it pair. >>>> >>>> BTW, should we replace others with cgroup_lock and cgroup_unlock? >>>> Since we already have a wrapper one and it's meaningful. >>>> >>>> >>> Before I read the email body, I thought there is a bug where >>> there is a lock without unlock or vise versa. >>> >>> I agree the case here can be called "unpaired", but I'm not >>> convinced this patch is needed. The code is not buggy or >>> confusing. So the patch neither fixes a bug nor make the code >>> more readable. >>> >>> >> I would say it fixes a bug, the one that would be introduced when the >> two methods are no longer compatible and essentially two names for the >> same thing. And while you may know the code so well that you knew >> without looking that this was (currently) okay, there will be lots of >> eyes on this code over the years, I think most people would find use of >> cgroup_lock to lock the cgroup a LOT more readable. >> >> While you can't go back in time to murder your grandfather, it creates >> no paradox to fix a bug before someone writes it. >> >> > > cgroup_lock() is not necessarily more readable than mutex_lock(&cgroup_mutex), > at least the former doesn't tell you the lock is a spin_lock or a mutex. > > That's the point, cgroup_lock() is an abstraction, you want to lock the cgroup, you call the macro, the macro handles the details, and if thinking (or the most common cache configurations) change, the code still works. > In fact, Ingo showed his distaste towards cgroup_lock(): > http://lkml.org/lkml/2009/1/18/39 > > And I won't worry about the issue you mentioned above. If It does > happen, the one, who makes the 2 mehtods no long compatible, will > definitely find out all the places where cgroup_mutex is used and > make proper change. > > -- Bill Davidsen <davidsen@xxxxxxx> Unintended results are the well-earned reward for incompetence. _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers
