linux-kernel - Re: [PATCH 2/2] cpuset: remove redundant checks in file write functions

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <520AE4FC.5090702@huawei.com>
Date:	Wed, 14 Aug 2013 10:01:32 +0800
From:	Li Zefan <lizefan@...wei.com>
To:	Tejun Heo <tj@...nel.org>
CC:	LKML <linux-kernel@...r.kernel.org>,
	cgroups <cgroups@...r.kernel.org>
Subject: Re: [PATCH 2/2] cpuset: remove redundant checks in file write functions

On 2013/8/13 23:05, Tejun Heo wrote:
> On Tue, Aug 13, 2013 at 09:17:53AM +0800, Li Zefan wrote:
>> Now cgroup core gets a reference to the css when a cgroup file is
>> opened(), and the reference is dropped at file release. so it's
>> guaranteed the cpuset is online during the write function.
> 
> Hmmm... it doesn't really guarantee that as css's can be offlined with
> residual css refcnts, os the css may well be offlined by the time it
> reaches the rw functions.  What's guaranteed is that their refcnts
> wouldn't be zero.

Oh, right.

But most controllers don't check this in those read/write functions.
It shoudn't do any harm not checking online/offline status.

> Eventually we need to implement proper sever
> semantics (probably by replacing the custom fs implementation with
> sysfs) but right now controllers still need to deal with offline
> css's.
> 
> Thanks.
> 

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/