Re: [PATCH 3/7] cgroups: Add previous cgroup in can_attach_task/attach_task callbacks

Paul Menage
2011-07-11T20:43:06Z

On Mon, Jul 11, 2011 at 7:15 AM, Frederic Weisbecker <fweisbec@gmail.com> wrote:
> This is to prepare the integration of a new max number of proc
> cgroup subsystem. We'll need to release some resources from the
> previous cgroup.
>
> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

Acked-by: Paul Menage <menage@google.com>

> Cc: Paul Menage <menage@google.com>
> Cc: Li Zefan <lizf@cn.fujitsu.com>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Aditya Kali <adityakali@google.com>
> ---
>  block/blk-cgroup.c      |   10 ++++++----
>  include/linux/cgroup.h  |    5 +++--
>  kernel/cgroup.c         |   10 ++++++----
>  kernel/cgroup_freezer.c |    3 ++-
>  kernel/cpuset.c         |    6 ++++--
>  kernel/events/core.c    |    5 +++--
>  kernel/sched.c          |    6 ++++--
>  7 files changed, 28 insertions(+), 17 deletions(-)
>
> diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
> index bcaf16e..d1bfe88 100644
> --- a/block/blk-cgroup.c
> +++ b/block/blk-cgroup.c
> @@ -30,8 +30,8 @@ EXPORT_SYMBOL_GPL(blkio_root_cgroup);
>
>  static struct cgroup_subsys_state *blkiocg_create(struct cgroup_subsys *,
>                                                  struct cgroup *);
> -static int blkiocg_can_attach_task(struct cgroup *, struct task_struct *);
> -static void blkiocg_attach_task(struct cgroup *, struct task_struct *);
> +static int blkiocg_can_attach_task(struct cgroup *, struct cgroup *, struct task_struct *);
> +static void blkiocg_attach_task(struct cgroup *, struct cgroup *, struct task_struct *);
>  static void blkiocg_destroy(struct cgroup_subsys *, struct cgroup *);
>  static int blkiocg_populate(struct cgroup_subsys *, struct cgroup *);
>
> @@ -1614,7 +1614,8 @@ done:
>  * of the main cic data structures.  For now we allow a task to change
>  * its cgroup only if it's the only owner of its ioc.
>  */
> -static int blkiocg_can_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
> +static int blkiocg_can_attach_task(struct cgroup *cgrp, struct cgroup *old_cgrp,
> +                                  struct task_struct *tsk)
>  {
>        struct io_context *ioc;
>        int ret = 0;
> @@ -1629,7 +1630,8 @@ static int blkiocg_can_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
>        return ret;
>  }
>
> -static void blkiocg_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
> +static void blkiocg_attach_task(struct cgroup *cgrp, struct cgroup *old_cgrp,
> +                               struct task_struct *tsk)
>  {
>        struct io_context *ioc;
>
> diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
> index ab4ac0c..e8288a0 100644
> --- a/include/linux/cgroup.h
> +++ b/include/linux/cgroup.h
> @@ -468,11 +468,12 @@ struct cgroup_subsys {
>        void (*destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp);
>        int (*can_attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
>                          struct task_struct *tsk);
> -       int (*can_attach_task)(struct cgroup *cgrp, struct task_struct *tsk);
> +       int (*can_attach_task)(struct cgroup *cgrp, struct cgroup *old_cgrp,
> +                              struct task_struct *tsk);
>        void (*cancel_attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
>                              struct task_struct *tsk);
>        void (*pre_attach)(struct cgroup *cgrp);
> -       void (*attach_task)(struct cgroup *cgrp, struct task_struct *tsk);
> +       void (*attach_task)(struct cgroup *cgrp, struct cgroup *old_cgrp, struct task_struct *tsk);
>        void (*attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
>                       struct cgroup *old_cgrp, struct task_struct *tsk);
>        void (*fork)(struct cgroup_subsys *ss, struct task_struct *task);
> diff --git a/kernel/cgroup.c b/kernel/cgroup.c
> index 2731d11..c3ee4cf 100644
> --- a/kernel/cgroup.c
> +++ b/kernel/cgroup.c
> @@ -1841,7 +1841,7 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
>                        }
>                }
>                if (ss->can_attach_task) {
> -                       retval = ss->can_attach_task(cgrp, tsk);
> +                       retval = ss->can_attach_task(cgrp, oldcgrp, tsk);
>                        if (retval) {
>                                failed_ss = ss;
>                                goto out;
> @@ -1857,7 +1857,7 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
>                if (ss->pre_attach)
>                        ss->pre_attach(cgrp);
>                if (ss->attach_task)
> -                       ss->attach_task(cgrp, tsk);
> +                       ss->attach_task(cgrp, oldcgrp, tsk);
>                if (ss->attach)
>                        ss->attach(ss, cgrp, oldcgrp, tsk);
>        }
> @@ -2072,7 +2072,9 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
>                        /* run on each task in the threadgroup. */
>                        for (i = 0; i < group_size; i++) {
>                                tsk = flex_array_get_ptr(group, i);
> -                               retval = ss->can_attach_task(cgrp, tsk);
> +                               oldcgrp = task_cgroup_from_root(tsk, root);
> +
> +                               retval = ss->can_attach_task(cgrp, oldcgrp, tsk);
>                                if (retval) {
>                                        failed_ss = ss;
>                                        cancel_failed_ss = true;
> @@ -2135,7 +2137,7 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader)
>                /* attach each task to each subsystem */
>                for_each_subsys(root, ss) {
>                        if (ss->attach_task)
> -                               ss->attach_task(cgrp, tsk);
> +                               ss->attach_task(cgrp, oldcgrp, tsk);
>                }
>                /* if the thread is PF_EXITING, it can just get skipped. */
>                retval = cgroup_task_migrate(cgrp, oldcgrp, tsk, true);
> diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
> index e691818..c1421a1 100644
> --- a/kernel/cgroup_freezer.c
> +++ b/kernel/cgroup_freezer.c
> @@ -175,7 +175,8 @@ static int freezer_can_attach(struct cgroup_subsys *ss,
>        return 0;
>  }
>
> -static int freezer_can_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
> +static int freezer_can_attach_task(struct cgroup *cgrp, struct cgroup *old_cgrp,
> +                                  struct task_struct *tsk)
>  {
>        rcu_read_lock();
>        if (__cgroup_freezing_or_frozen(tsk)) {
> diff --git a/kernel/cpuset.c b/kernel/cpuset.c
> index 9c9b754..f66c9b4 100644
> --- a/kernel/cpuset.c
> +++ b/kernel/cpuset.c
> @@ -1390,7 +1390,8 @@ static int cpuset_can_attach(struct cgroup_subsys *ss, struct cgroup *cont,
>        return 0;
>  }
>
> -static int cpuset_can_attach_task(struct cgroup *cgrp, struct task_struct *task)
> +static int cpuset_can_attach_task(struct cgroup *cgrp, struct cgroup *old_cgrp,
> +                                 struct task_struct *task)
>  {
>        return security_task_setscheduler(task);
>  }
> @@ -1418,7 +1419,8 @@ static void cpuset_pre_attach(struct cgroup *cont)
>  }
>
>  /* Per-thread attachment work. */
> -static void cpuset_attach_task(struct cgroup *cont, struct task_struct *tsk)
> +static void cpuset_attach_task(struct cgroup *cont, struct cgroup *old,
> +                              struct task_struct *tsk)
>  {
>        int err;
>        struct cpuset *cs = cgroup_cs(cont);
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index 9efe710..3daf0eb 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -7403,7 +7403,8 @@ static int __perf_cgroup_move(void *info)
>  }
>
>  static void
> -perf_cgroup_attach_task(struct cgroup *cgrp, struct task_struct *task)
> +perf_cgroup_attach_task(struct cgroup *cgrp, struct cgroup *old_cgrp,
> +                       struct task_struct *task)
>  {
>        task_function_call(task, __perf_cgroup_move, task);
>  }
> @@ -7419,7 +7420,7 @@ static void perf_cgroup_exit(struct cgroup_subsys *ss, struct cgroup *cgrp,
>        if (!(task->flags & PF_EXITING))
>                return;
>
> -       perf_cgroup_attach_task(cgrp, task);
> +       perf_cgroup_attach_task(cgrp, old_cgrp, task);
>  }
>
>  struct cgroup_subsys perf_subsys = {
> diff --git a/kernel/sched.c b/kernel/sched.c
> index 3f2e502..adec58d 100644
> --- a/kernel/sched.c
> +++ b/kernel/sched.c
> @@ -8790,7 +8790,8 @@ cpu_cgroup_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
>  }
>
>  static int
> -cpu_cgroup_can_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
> +cpu_cgroup_can_attach_task(struct cgroup *cgrp, struct cgroup *old_cgrp,
> +                          struct task_struct *tsk)
>  {
>  #ifdef CONFIG_RT_GROUP_SCHED
>        if (!sched_rt_can_attach(cgroup_tg(cgrp), tsk))
> @@ -8804,7 +8805,8 @@ cpu_cgroup_can_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
>  }
>
>  static void
> -cpu_cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
> +cpu_cgroup_attach_task(struct cgroup *cgrp, struct cgroup *old_cgrp,
> +                      struct task_struct *tsk)
>  {
>        sched_move_task(tsk);
>  }
> --
> 1.7.5.4
>
>