pm24.git/kernel/cgroup_freezer.c, branch v2.6.32

cgroups: let ss->can_attach and ss->attach do whole threadgroups at a time

2009-09-24T14:20:58Z

Alter the ss->can_attach and ss->attach functions to be able to deal with a whole threadgroup at a time, for use in cgroup_attach_proc. (This is a pre-patch to cgroup-procs-writable.patch.) Currently, new mode of the attach function can only tell the subsystem about the old cgroup of the threadgroup leader. No subsystem currently needs that information for each thread that's being moved, but if one were to be added (for example, one that counts tasks within a group) this bit would need to be reworked a bit to tell the subsystem the right information. [hidave.darkstar@gmail.com: fix build] Signed-off-by: Ben Blum Signed-off-by: Paul Menage Acked-by: Li Zefan Reviewed-by: Matt Helsley Cc: "Eric W. Biederman" Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Dave Young Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

freezer_cg: disable writing freezer.state of root cgroup

2008-11-13T01:17:16Z

With this change, control file 'freezer.state' doesn't exist in root cgroup, making root cgroup unfreezable. I think it's reasonable to disallow freeze tasks in the root cgroup. And then we can avoid fork overhead when freezer subsystem is compiled but not used. Also make writing invalid value to freezer.state returns EINVAL rather than EIO. This is more consistent with other cgroup subsystem. Signed-off-by: Li Zefan Acked-by: Paul Menage Cc: Cedric Le Goater Cc: Paul Menage Cc: Matt Helsley Cc: "Serge E. Hallyn" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

freezer_cg: remove task_lock from freezer_fork()

2008-11-13T01:17:16Z

In theory the task can be moved to another cgroup and the freezer will be freed right after task_lock is dropped, so the lock results in zero protection. But in the case of freezer_fork() no lock is needed, since the task is not in tasklist yet so it won't be moved to another cgroup, so task->cgroups won't be changed or invalidated. Signed-off-by: Li Zefan Cc: Matt Helsley Cc: Cedric Le Goater Cc: "Serge E. Hallyn" Cc: Paul Menage Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

freezer_cg: simplify freezer_change_state()

2008-10-30T18:38:45Z

Just call unfreeze_cgroup() if goal_state == THAWED, and call try_to_freeze_cgroup() if goal_state == FROZEN. No behavior has been changed. Signed-off-by: Li Zefan Acked-by: Cedric Le Goater Acked-by: Matt Helsley Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

freezer_cg: use thaw_process() in unfreeze_cgroup()

2008-10-30T18:38:45Z

Don't duplicate the implementation of thaw_process(). [akpm@linux-foundation.org: make __thaw_process() static] Signed-off-by: Li Zefan Cc: Cedric Le Goater Acked-by: Matt Helsley Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

freezer_cg: remove redundant check in freezer_can_attach()

2008-10-30T18:38:45Z

It is sufficient to check if @task is frozen, and no need to check if the original freezer is frozen. Signed-off-by: Li Zefan Acked-by: Cedric Le Goater Acked-by: Matt Helsley Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

freezer_cg: fix improper BUG_ON() causing oops

2008-10-30T18:38:45Z

The BUG_ON() should be protected by freezer->lock, otherwise it can be triggered easily when a task has been unfreezed but the corresponding cgroup hasn't been changed to FROZEN state. Signed-off-by: Li Zefan Acked-by: Cedric Le Goater Acked-by: Matt Helsley Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

container freezer: rename check_if_frozen()

2008-10-20T15:52:34Z

check_if_frozen() sounds like it should return something when in fact it's just updating the freezer state. Signed-off-by: Matt Helsley Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

container freezer: make freezer state names less generic

2008-10-20T15:52:34Z

Rename cgroup freezer states to be less generic to avoid any name collisions while also better describing what each state is. Signed-off-by: Matt Helsley Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

container freezer: prevent frozen tasks or cgroups from changing

2008-10-20T15:52:34Z

Don't let frozen tasks or cgroups change. This means frozen tasks can't leave their current cgroup for another cgroup. It also means that tasks cannot be added to or removed from a cgroup in the FROZEN state. We enforce these rules by checking for frozen tasks and cgroups in the can_attach() function. Signed-off-by: Matt Helsley Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds