linux-toradex.git/include/linux/cgroup.h, branch v2.6.27.50

cgroup_clone: use pid of newly created task for new cgroup

2008-07-25T17:53:37+00:00

cgroup_clone creates a new cgroup with the pid of the task.  This works
correctly for unshare, but for clone cgroup_clone is called from
copy_namespaces inside copy_process, which happens before the new pid is
created.  As a result, the new cgroup was created with current's pid.
This patch:

	1. Moves the call inside copy_process to after the new pid
	   is created
	2. Passes the struct pid into ns_cgroup_clone (as it is not
	   yet attached to the task)
	3. Passes a name from ns_cgroup_clone() into cgroup_clone()
	   so as to keep cgroup_clone() itself simpler
	4. Uses pid_vnr() to get the process id value, so that the
	   pid used to name the new cgroup is always the pid as it
	   would be known to the task which did the cloning or
	   unsharing.  I think that is the most intuitive thing to
	   do.  This way, task t1 does clone(CLONE_NEWPID) to get
	   t2, which does clone(CLONE_NEWPID) to get t3, then the
	   cgroup for t3 will be named for the pid by which t2 knows
	   t3.

(Thanks to Dan Smith for finding the main bug)

Changelog:
	June 11: Incorporate Paul Menage's feedback:  don't pass
	         NULL to ns_cgroup_clone from unshare, and reduce
		 patch size by using 'nodename' in cgroup_clone.
	June 10: Original version

[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Serge Hallyn 
Acked-by: Paul Menage 
Tested-by: Dan Smith 
Cc: Balbir Singh 
Cc: KAMEZAWA Hiroyuki 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cgroups: misc cleanups to write_string patchset

2008-07-25T17:53:35+00:00

This patch contains cleanups suggested by reviewers for the recent
write_string() patchset:

- pair cgroup_lock_live_group() with cgroup_unlock() in cgroup.c for
  clarity, rather than directly unlocking cgroup_mutex.

- make the return type of cgroup_lock_live_group() a bool

- use a #define'd constant for the local buffer size in read/write functions

Signed-off-by: Paul Menage 
Cc: Paul Jackson 
Cc: Pavel Emelyanov 
Cc: Balbir Singh 
Acked-by: Serge Hallyn 
Cc: KAMEZAWA Hiroyuki 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cgroup files: move the release_agent file to use typed handlers

2008-07-25T17:53:35+00:00

Adds cgroup_release_agent_write() and cgroup_release_agent_show()
methods to handle writing/reading the path to a cgroup hierarchy's
release agent. As a result, cgroup_common_file_read() is now unnecessary.

As part of the change, a previously-tolerated race in
cgroup_release_agent() is avoided by copying the current
release_agent_path prior to calling call_usermode_helper().

Signed-off-by: Paul Menage 
Cc: Paul Jackson 
Cc: Pavel Emelyanov 
Cc: Balbir Singh 
Acked-by: Serge Hallyn 
Cc: KAMEZAWA Hiroyuki 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cgroup files: add write_string cgroup control file method

2008-07-25T17:53:35+00:00

This patch adds a write_string() method for cgroups control files. The
semantics are that a buffer is copied from userspace to kernelspace
and the handler function invoked on that buffer.  The buffer is
guaranteed to be nul-terminated, and no longer than max_write_len
(defaulting to 64 bytes if unspecified). Later patches will convert
existing raw file write handlers in control group subsystems to use
this method.

Signed-off-by: Paul Menage 
Cc: Paul Jackson 
Cc: Pavel Emelyanov 
Acked-by: Balbir Singh 
Acked-by: Serge Hallyn 
Cc: KAMEZAWA Hiroyuki 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cgroup files: clean up whitespace in struct cftype

2008-07-25T17:53:35+00:00

This patch removes some extraneous spaces from method declarations in
struct cftype, to fit in with conventional kernel style.

Signed-off-by: Paul Menage 
Cc: Paul Jackson 
Cc: Pavel Emelyanov 
Cc: Balbir Singh 
Cc: Serge Hallyn 
Cc: KAMEZAWA Hiroyuki 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cgroups: add an owner to the mm_struct

2008-04-29T15:06:10+00:00

Remove the mem_cgroup member from mm_struct and instead adds an owner.

This approach was suggested by Paul Menage.  The advantage of this approach
is that, once the mm->owner is known, using the subsystem id, the cgroup
can be determined.  It also allows several control groups that are
virtually grouped by mm_struct, to exist independent of the memory
controller i.e., without adding mem_cgroup's for each controller, to
mm_struct.

A new config option CONFIG_MM_OWNER is added and the memory resource
controller selects this config option.

This patch also adds cgroup callbacks to notify subsystems when mm->owner
changes.  The mm_cgroup_changed callback is called with the task_lock() of
the new task held and is called just prior to changing the mm->owner.

I am indebted to Paul Menage for the several reviews of this patchset and
helping me make it lighter and simpler.

This patch was tested on a powerpc box, it was compiled with both the
MM_OWNER config turned on and off.

After the thread group leader exits, it's moved to init_css_state by
cgroup_exit(), thus all future charges from runnings threads would be
redirected to the init_css_set's subsystem.

Signed-off-by: Balbir Singh 
Cc: Pavel Emelianov 
Cc: Hugh Dickins 
Cc: Sudhir Kumar 
Cc: YAMAMOTO Takashi 
Cc: Hirokazu Takahashi 
Cc: David Rientjes ,
Cc: Balbir Singh 
Acked-by: KAMEZAWA Hiroyuki 
Acked-by: Pekka Enberg 
Reviewed-by: Paul Menage 
Cc: Oleg Nesterov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cgroups: introduce cft->read_seq()

2008-04-29T15:06:10+00:00

Introduce a read_seq() helper in cftype, which uses seq_file to print out
lists.  Use it in the devices cgroup.  Also split devices.allow into two
files, so now devices.deny and devices.allow are the ones to use to manipulate
the whitelist, while devices.list outputs the cgroup's current whitelist.

Signed-off-by: Serge E. Hallyn 
Acked-by: Paul Menage 
Cc: Balbir Singh 
Cc: KAMEZAWA Hiroyuki 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cgroups: remove the css_set linked-list

2008-04-29T15:06:10+00:00

Now we can run through the hash table instead of running through the
linked-list.

Signed-off-by: Li Zefan 
Reviewed-by: Paul Menage 
Cc: Balbir Singh 
Cc: Pavel Emelyanov 
Cc: KAMEZAWA Hiroyuki 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cgroups: use a hash table for css_set finding

2008-04-29T15:06:09+00:00

When we attach a process to a different cgroup, the css_set linked-list will
be run through to find a suitable existing css_set to use.  This patch
implements a hash table for better performance.

The following benchmarks have been tested:

For N in 1, 5, 10, 50, 100, 500, 1000, create N cgroups with one sleeping
task in each, and then move an additional task through each cgroup in
turn.

Here is a test result:

N	Loop	orig - Time(s)	hash - Time(s)
----------------------------------------------
1	10000	1.201231728	1.196311177
5	2000	1.065743872	1.040566424
10	1000	0.991054735	0.986876440
50	200	0.976554203	0.969608733
100	100	0.998504680	0.969218270
500	20	1.157347764	0.962602963
1000	10	1.619521852	1.085140172

Signed-off-by: Li Zefan 
Reviewed-by: Paul Menage 
Cc: Balbir Singh 
Cc: Pavel Emelyanov 
Cc: KAMEZAWA Hiroyuki 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cgroups: add the trigger callback to struct cftype

2008-04-29T15:06:09+00:00

Trigger callback can be used to receive a kick-up from the user space.  The
string written is ignored.

The cftype->private is used for multiplexing events.

Signed-off-by: Pavel Emelyanov 
Acked-by: Paul Menage 
Acked-by: KAMEZAWA Hiroyuki 
Cc: Balbir Singh 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds