Re: [PATCH 05/16] freezer: rename thaw_process() to __thaw_task() andsimplify the implementation

[Paul Menage]

On Fri, Aug 19, 2011 at 7:16 AM, Tejun Heo <tj@xxxxxxxxxx> wrote:
> thaw_process() now has only internal users - system and cgroup
> freezers.  Remove the unnecessary return value, rename, unexport and
> collapse __thaw_process() into it.  This will help further updates to
> the freezer code.
>
> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
> Cc: Paul Menage <menage@xxxxxxxxxx>

Probably better to have Matt Helsley look at this?

Paul

> ---
>  include/linux/freezer.h |    3 +--
>  kernel/cgroup_freezer.c |    7 +++----
>  kernel/freezer.c        |   30 +++++++++++-------------------
>  kernel/power/process.c  |    2 +-
>  4 files changed, 16 insertions(+), 26 deletions(-)
>
> diff --git a/include/linux/freezer.h b/include/linux/freezer.h
> index 8ee31e5..80a455d 100644
> --- a/include/linux/freezer.h
> +++ b/include/linux/freezer.h
> @@ -45,7 +45,7 @@ static inline bool should_send_signal(struct task_struct *p)
>  }
>
>  /* Takes and releases task alloc lock using task_lock() */
> -extern int thaw_process(struct task_struct *p);
> +extern void __thaw_task(struct task_struct *t);
>
>  extern bool __refrigerator(bool check_kthr_stop);
>  extern int freeze_processes(void);
> @@ -167,7 +167,6 @@ static inline int frozen(struct task_struct *p) { return 0; }
>  static inline int freezing(struct task_struct *p) { return 0; }
>  static inline void set_freeze_flag(struct task_struct *p) {}
>  static inline void clear_freeze_flag(struct task_struct *p) {}
> -static inline int thaw_process(struct task_struct *p) { return 1; }
>
>  static inline bool __refrigerator(bool check_kthr_stop) { return false; }
>  static inline int freeze_processes(void) { BUG(); return 0; }
> diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
> index e691818..e7fa0ec 100644
> --- a/kernel/cgroup_freezer.c
> +++ b/kernel/cgroup_freezer.c
> @@ -130,7 +130,7 @@ struct cgroup_subsys freezer_subsys;
>  *   write_lock css_set_lock (cgroup iterator start)
>  *    task->alloc_lock
>  *   read_lock css_set_lock (cgroup iterator start)
> - *    task->alloc_lock (inside thaw_process(), prevents race with refrigerator())
> + *    task->alloc_lock (inside __thaw_task(), prevents race with refrigerator())
>  *     sighand->siglock
>  */
>  static struct cgroup_subsys_state *freezer_create(struct cgroup_subsys *ss,
> @@ -300,9 +300,8 @@ static void unfreeze_cgroup(struct cgroup *cgroup, struct freezer *freezer)
>        struct task_struct *task;
>
>        cgroup_iter_start(cgroup, &it);
> -       while ((task = cgroup_iter_next(cgroup, &it))) {
> -               thaw_process(task);
> -       }
> +       while ((task = cgroup_iter_next(cgroup, &it)))
> +               __thaw_task(task);
>        cgroup_iter_end(cgroup, &it);
>
>        freezer->state = CGROUP_THAWED;
> diff --git a/kernel/freezer.c b/kernel/freezer.c
> index 656492c..f5db7fd 100644
> --- a/kernel/freezer.c
> +++ b/kernel/freezer.c
> @@ -145,18 +145,8 @@ void cancel_freezing(struct task_struct *p)
>        }
>  }
>
> -static int __thaw_process(struct task_struct *p)
> -{
> -       if (frozen(p)) {
> -               p->flags &= ~PF_FROZEN;
> -               return 1;
> -       }
> -       clear_freeze_flag(p);
> -       return 0;
> -}
> -
>  /*
> - * Wake up a frozen process
> + * Wake up a frozen task
>  *
>  * task_lock() is needed to prevent the race with refrigerator() which may
>  * occur if the freezing of tasks fails.  Namely, without the lock, if the
> @@ -164,15 +154,17 @@ static int __thaw_process(struct task_struct *p)
>  * refrigerator() could call frozen_process(), in which case the task would be
>  * frozen and no one would thaw it.
>  */
> -int thaw_process(struct task_struct *p)
> +void __thaw_task(struct task_struct *p)
>  {
> +       bool was_frozen;
> +
>        task_lock(p);
> -       if (__thaw_process(p) == 1) {
> -               task_unlock(p);
> -               wake_up_process(p);
> -               return 1;
> -       }
> +       if ((was_frozen = frozen(p)))
> +               p->flags &= ~PF_FROZEN;
> +       else
> +               clear_freeze_flag(p);
>        task_unlock(p);
> -       return 0;
> +
> +       if (was_frozen)
> +               wake_up_process(p);
>  }
> -EXPORT_SYMBOL(thaw_process);
> diff --git a/kernel/power/process.c b/kernel/power/process.c
> index 0cf3a27..bec09c3 100644
> --- a/kernel/power/process.c
> +++ b/kernel/power/process.c
> @@ -176,7 +176,7 @@ static void thaw_tasks(bool nosig_only)
>                if (cgroup_freezing_or_frozen(p))
>                        continue;
>
> -               thaw_process(p);
> +               __thaw_task(p);
>        } while_each_thread(g, p);
>        read_unlock(&tasklist_lock);
>  }
> --
> 1.7.6
>
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