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From: "Paul Menage" <menage@google.com>
To: balbir@linux.vnet.ibm.com
Cc: akpm@linux-foundation.org, dev@sw.ru, xemul@sw.ru,
	serue@us.ibm.com, vatsa@in.ibm.com, ebiederm@xmission.com,
	haveblue@us.ibm.com, svaidy@linux.vnet.ibm.com,
	balbir@in.ibm.com, pj@sgi.com, ckrm-tech@lists.sourceforge.net,
	linux-kernel@vger.kernel.org, rohitseth@google.com,
	mbligh@google.com, containers@lists.osdl.org, devel@openvz.org
Subject: Re: [PATCH 1/9] Containers (V9): Basic container framework
Date: Tue, 1 May 2007 10:46:10 -0700	[thread overview]
Message-ID: <6599ad830705011046l6d0a0db7jd28d29f8c1b8cdb9@mail.gmail.com> (raw)
In-Reply-To: <46377BA4.6030701@linux.vnet.ibm.com>

On 5/1/07, Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
> menage@google.com wrote:
> > This patch adds the main containers framework - the container
> > filesystem, and the basic structures for tracking membership and
> > associating subsystem state objects to tasks.
>
> [snip]
>
> > +*** notify_on_release is disabled in the current patch set. It may be
> > +*** reactivated in a future patch in a less-intrusive manner
> > +
>
> Won't this break user space tools for cpusets?

Yes, so it's a must-fix before this gets anywhere near a real distribution.

>
> [snip]
>
> > +See kernel/container.c for more details.
> > +
> > +Subsystems can take/release the container_mutex via the functions
> > +container_lock()/container_unlock(), and can
> > +take/release the callback_mutex via the functions
> > +container_lock()/container_unlock().
> > +
>
> Hmm.. looks like a documentation error. Both mutex's are obtained through
> container_lock/container_unlock ?

The second half of that sentence is obsolete and should have been deleted.

>
> > +Accessing a task's container pointer may be done in the following ways:
> > +- while holding container_mutex
> > +- while holding the task's alloc_lock (via task_lock())
> > +- inside an rcu_read_lock() section via rcu_dereference()
> > +
>
> container_mutex() and task_lock() can be used for changing the pointer?

No, these are all for read operations. (Actually, this is a bit of
documentation that's bit-rotted - there's no longer a per-task
"container" pointer). I'll update this.

For write operations, only the container system should be modifying
those pointers (under the protection of both container_mutex and
alloc_lock).

>
> We needed the equivalent of container_remove_file() to be called
> if container_add_file() failed.
>

Yes, this is some incomplete behaviour that I inherited from cpusets.
Needs tidying up.

>
> Can't we derive the top_container from containerfs_root?

Yes, we could for the cost of an extra dereference. Not sure it's a
big deal either way.

> > +     ssize_t (*read) (struct container *cont, struct cftype *cft,
> > +                      struct file *file,
> > +                      char __user *buf, size_t nbytes, loff_t *ppos);
> > +     u64 (*read_uint) (struct container *cont, struct cftype *cft);
>
> Is this a new callback, a specialization of the read() callback?

Yes. It's to simplify the common case of reporting a number in a
control file. (Not yet well documented :-( )

Paul

  reply	other threads:[~2007-05-01 17:46 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-04-27 10:46 [PATCH 0/9] Containers (V9): Generic Process Containers menage
2007-04-27 10:46 ` [PATCH 1/9] Containers (V9): Basic container framework menage
2007-04-29  3:12   ` [ckrm-tech] " Paul Jackson
2007-05-01 17:40   ` Balbir Singh
2007-05-01 17:46     ` Paul Menage [this message]
2007-05-01 18:40     ` [ckrm-tech] " Paul Jackson
2007-05-02  3:44       ` Balbir Singh
2007-05-02  6:12         ` Paul Jackson
2007-05-10  4:09           ` Balbir Singh
2007-05-10  4:47             ` Paul Jackson
2007-05-10  4:49               ` Balbir Singh
2007-04-27 10:46 ` [PATCH 2/9] Containers (V9): Example CPU accounting subsystem menage
2007-05-01 17:52   ` Balbir Singh
2007-04-27 10:46 ` [PATCH 3/9] Containers (V9): Add tasks file interface menage
2007-05-01 18:12   ` Balbir Singh
2007-05-01 20:37     ` [ckrm-tech] " Paul Menage
2007-05-02  3:25       ` Srivatsa Vaddagiri
2007-05-02  3:25         ` Paul Menage
2007-05-02  3:46           ` Srivatsa Vaddagiri
2007-05-08 14:51           ` Balbir Singh
2007-05-10 21:21             ` Paul Menage
2007-05-11  2:31               ` Balbir Singh
2007-05-02  3:58       ` Balbir Singh
2007-04-27 10:46 ` [PATCH 4/9] Containers (V9): Add fork/exit hooks menage
2007-04-27 10:46 ` [PATCH 5/9] Containers (V9): Add container_clone() interface menage
2007-04-27 10:46 ` [PATCH 6/9] Containers (V9): Add procfs interface menage
2007-04-27 10:46 ` [PATCH 7/9] Containers (V9): Make cpusets a client of containers menage
2007-04-27 10:46 ` [PATCH 8/9] Containers (V9): Share css_group arrays between tasks with same container memberships menage
2007-04-27 10:46 ` [PATCH 9/9] Containers (V9): Simple debug info subsystem menage
2007-04-29  1:47 ` [PATCH 0/9] Containers (V9): Generic Process Containers Paul Jackson
2007-04-29  9:37 ` Paul Jackson
2007-04-30 17:12   ` Srivatsa Vaddagiri
2007-04-30 17:09     ` Paul Menage
2007-04-30 18:06       ` Srivatsa Vaddagiri
2007-04-30 17:23     ` Christoph Hellwig
2007-04-30 18:16       ` [ckrm-tech] " Srivatsa Vaddagiri

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