Re: [PATCH 21/23] cgroup: make cftype->[un]register_event() dealwith cgroup_subsys_state instead of cgroup

[Michal Hocko]

On Thu 01-08-13 17:49:59, Tejun Heo wrote:
> cgroup is in the process of converting to css (cgroup_subsys_state)
> from cgroup as the principal subsystem interface handle.  This is
> mostly to prepare for the unified hierarchy support where css's will
> be created and destroyed dynamically but also helps cleaning up
> subsystem implementations as css is usually what they are interested
> in anyway.
> 
> cftype->[un]register_event() is among the remaining couple interfaces
> which still use struct cgroup.  Convert it to cgroup_subsys_state.
> The conversion is mostly mechanical and removes the last users of
> mem_cgroup_from_cont() and cg_to_vmpressure(), which are removed.
> 
> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
> Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxx>
> Cc: Balbir Singh <bsingharora@xxxxxxxxx>

Acked-by: Michal Hocko <mhocko@xxxxxxx>

> ---
>  include/linux/cgroup.h     |  8 +++++---
>  include/linux/vmpressure.h |  6 ++++--
>  kernel/cgroup.c            | 15 ++++++++-------
>  mm/memcontrol.c            | 21 ++++++++-------------
>  mm/vmpressure.c            | 21 +++++++++------------
>  5 files changed, 34 insertions(+), 37 deletions(-)
> 
> diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
> index 6f6d87b..8f44411 100644
> --- a/include/linux/cgroup.h
> +++ b/include/linux/cgroup.h
> @@ -506,15 +506,17 @@ struct cftype {
>  	 * you want to provide this functionality. Use eventfd_signal()
>  	 * on eventfd to send notification to userspace.
>  	 */
> -	int (*register_event)(struct cgroup *cgrp, struct cftype *cft,
> -			struct eventfd_ctx *eventfd, const char *args);
> +	int (*register_event)(struct cgroup_subsys_state *css,
> +			      struct cftype *cft, struct eventfd_ctx *eventfd,
> +			      const char *args);
>  	/*
>  	 * unregister_event() callback will be called when userspace
>  	 * closes the eventfd or on cgroup removing.
>  	 * This callback must be implemented, if you want provide
>  	 * notification functionality.
>  	 */
> -	void (*unregister_event)(struct cgroup *cgrp, struct cftype *cft,
> +	void (*unregister_event)(struct cgroup_subsys_state *css,
> +				 struct cftype *cft,
>  			struct eventfd_ctx *eventfd);
>  };
>  
> diff --git a/include/linux/vmpressure.h b/include/linux/vmpressure.h
> index 76be077..b239482 100644
> --- a/include/linux/vmpressure.h
> +++ b/include/linux/vmpressure.h
> @@ -33,10 +33,12 @@ extern void vmpressure_init(struct vmpressure *vmpr);
>  extern struct vmpressure *memcg_to_vmpressure(struct mem_cgroup *memcg);
>  extern struct cgroup_subsys_state *vmpressure_to_css(struct vmpressure *vmpr);
>  extern struct vmpressure *css_to_vmpressure(struct cgroup_subsys_state *css);
> -extern int vmpressure_register_event(struct cgroup *cg, struct cftype *cft,
> +extern int vmpressure_register_event(struct cgroup_subsys_state *css,
> +				     struct cftype *cft,
>  				     struct eventfd_ctx *eventfd,
>  				     const char *args);
> -extern void vmpressure_unregister_event(struct cgroup *cg, struct cftype *cft,
> +extern void vmpressure_unregister_event(struct cgroup_subsys_state *css,
> +					struct cftype *cft,
>  					struct eventfd_ctx *eventfd);
>  #else
>  static inline void vmpressure(gfp_t gfp, struct mem_cgroup *memcg,
> diff --git a/kernel/cgroup.c b/kernel/cgroup.c
> index c61b24f..e0ef58e 100644
> --- a/kernel/cgroup.c
> +++ b/kernel/cgroup.c
> @@ -159,9 +159,9 @@ struct css_id {
>   */
>  struct cgroup_event {
>  	/*
> -	 * Cgroup which the event belongs to.
> +	 * css which the event belongs to.
>  	 */
> -	struct cgroup *cgrp;
> +	struct cgroup_subsys_state *css;
>  	/*
>  	 * Control file which the event associated.
>  	 */
> @@ -3948,11 +3948,12 @@ static void cgroup_event_remove(struct work_struct *work)
>  {
>  	struct cgroup_event *event = container_of(work, struct cgroup_event,
>  			remove);
> -	struct cgroup *cgrp = event->cgrp;
> +	struct cgroup_subsys_state *css = event->css;
> +	struct cgroup *cgrp = css->cgroup;
>  
>  	remove_wait_queue(event->wqh, &event->wait);
>  
> -	event->cft->unregister_event(cgrp, event->cft, event->eventfd);
> +	event->cft->unregister_event(css, event->cft, event->eventfd);
>  
>  	/* Notify userspace the event is going away. */
>  	eventfd_signal(event->eventfd, 1);
> @@ -3972,7 +3973,7 @@ static int cgroup_event_wake(wait_queue_t *wait, unsigned mode,
>  {
>  	struct cgroup_event *event = container_of(wait,
>  			struct cgroup_event, wait);
> -	struct cgroup *cgrp = event->cgrp;
> +	struct cgroup *cgrp = event->css->cgroup;
>  	unsigned long flags = (unsigned long)key;
>  
>  	if (flags & POLLHUP) {
> @@ -4041,7 +4042,7 @@ static int cgroup_write_event_control(struct cgroup_subsys_state *css,
>  	event = kzalloc(sizeof(*event), GFP_KERNEL);
>  	if (!event)
>  		return -ENOMEM;
> -	event->cgrp = cgrp;
> +	event->css = css;
>  	INIT_LIST_HEAD(&event->list);
>  	init_poll_funcptr(&event->pt, cgroup_event_ptable_queue_proc);
>  	init_waitqueue_func_entry(&event->wait, cgroup_event_wake);
> @@ -4092,7 +4093,7 @@ static int cgroup_write_event_control(struct cgroup_subsys_state *css,
>  		goto out_put_cfile;
>  	}
>  
> -	ret = event->cft->register_event(cgrp, event->cft,
> +	ret = event->cft->register_event(css, event->cft,
>  			event->eventfd, buffer);
>  	if (ret)
>  		goto out_put_cfile;
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 95106a9..2885e3e 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -1034,11 +1034,6 @@ static void memcg_check_events(struct mem_cgroup *memcg, struct page *page)
>  		preempt_enable();
>  }
>  
> -static inline struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
> -{
> -	return mem_cgroup_from_css(cgroup_css(cont, mem_cgroup_subsys_id));
> -}
> -
>  struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
>  {
>  	/*
> @@ -5620,10 +5615,10 @@ static void mem_cgroup_oom_notify(struct mem_cgroup *memcg)
>  		mem_cgroup_oom_notify_cb(iter);
>  }
>  
> -static int mem_cgroup_usage_register_event(struct cgroup *cgrp,
> +static int mem_cgroup_usage_register_event(struct cgroup_subsys_state *css,
>  	struct cftype *cft, struct eventfd_ctx *eventfd, const char *args)
>  {
> -	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
> +	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
>  	struct mem_cgroup_thresholds *thresholds;
>  	struct mem_cgroup_threshold_ary *new;
>  	enum res_type type = MEMFILE_TYPE(cft->private);
> @@ -5703,10 +5698,10 @@ unlock:
>  	return ret;
>  }
>  
> -static void mem_cgroup_usage_unregister_event(struct cgroup *cgrp,
> +static void mem_cgroup_usage_unregister_event(struct cgroup_subsys_state *css,
>  	struct cftype *cft, struct eventfd_ctx *eventfd)
>  {
> -	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
> +	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
>  	struct mem_cgroup_thresholds *thresholds;
>  	struct mem_cgroup_threshold_ary *new;
>  	enum res_type type = MEMFILE_TYPE(cft->private);
> @@ -5782,10 +5777,10 @@ unlock:
>  	mutex_unlock(&memcg->thresholds_lock);
>  }
>  
> -static int mem_cgroup_oom_register_event(struct cgroup *cgrp,
> +static int mem_cgroup_oom_register_event(struct cgroup_subsys_state *css,
>  	struct cftype *cft, struct eventfd_ctx *eventfd, const char *args)
>  {
> -	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
> +	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
>  	struct mem_cgroup_eventfd_list *event;
>  	enum res_type type = MEMFILE_TYPE(cft->private);
>  
> @@ -5807,10 +5802,10 @@ static int mem_cgroup_oom_register_event(struct cgroup *cgrp,
>  	return 0;
>  }
>  
> -static void mem_cgroup_oom_unregister_event(struct cgroup *cgrp,
> +static void mem_cgroup_oom_unregister_event(struct cgroup_subsys_state *css,
>  	struct cftype *cft, struct eventfd_ctx *eventfd)
>  {
> -	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
> +	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
>  	struct mem_cgroup_eventfd_list *ev, *tmp;
>  	enum res_type type = MEMFILE_TYPE(cft->private);
>  
> diff --git a/mm/vmpressure.c b/mm/vmpressure.c
> index 2a8a736..13489b1 100644
> --- a/mm/vmpressure.c
> +++ b/mm/vmpressure.c
> @@ -74,11 +74,6 @@ static struct vmpressure *work_to_vmpressure(struct work_struct *work)
>  	return container_of(work, struct vmpressure, work);
>  }
>  
> -static struct vmpressure *cg_to_vmpressure(struct cgroup *cg)
> -{
> -	return css_to_vmpressure(cgroup_css(cg, mem_cgroup_subsys_id));
> -}
> -
>  static struct vmpressure *vmpressure_parent(struct vmpressure *vmpr)
>  {
>  	struct cgroup_subsys_state *css = vmpressure_to_css(vmpr);
> @@ -283,7 +278,7 @@ void vmpressure_prio(gfp_t gfp, struct mem_cgroup *memcg, int prio)
>  
>  /**
>   * vmpressure_register_event() - Bind vmpressure notifications to an eventfd
> - * @cg:		cgroup that is interested in vmpressure notifications
> + * @css:	css that is interested in vmpressure notifications
>   * @cft:	cgroup control files handle
>   * @eventfd:	eventfd context to link notifications with
>   * @args:	event arguments (used to set up a pressure level threshold)
> @@ -298,10 +293,11 @@ void vmpressure_prio(gfp_t gfp, struct mem_cgroup *memcg, int prio)
>   * cftype).register_event, and then cgroup core will handle everything by
>   * itself.
>   */
> -int vmpressure_register_event(struct cgroup *cg, struct cftype *cft,
> -			      struct eventfd_ctx *eventfd, const char *args)
> +int vmpressure_register_event(struct cgroup_subsys_state *css,
> +			      struct cftype *cft, struct eventfd_ctx *eventfd,
> +			      const char *args)
>  {
> -	struct vmpressure *vmpr = cg_to_vmpressure(cg);
> +	struct vmpressure *vmpr = css_to_vmpressure(css);
>  	struct vmpressure_event *ev;
>  	int level;
>  
> @@ -329,7 +325,7 @@ int vmpressure_register_event(struct cgroup *cg, struct cftype *cft,
>  
>  /**
>   * vmpressure_unregister_event() - Unbind eventfd from vmpressure
> - * @cg:		cgroup handle
> + * @css:	css handle
>   * @cft:	cgroup control files handle
>   * @eventfd:	eventfd context that was used to link vmpressure with the @cg
>   *
> @@ -341,10 +337,11 @@ int vmpressure_register_event(struct cgroup *cg, struct cftype *cft,
>   * cftype).unregister_event, and then cgroup core will handle everything
>   * by itself.
>   */
> -void vmpressure_unregister_event(struct cgroup *cg, struct cftype *cft,
> +void vmpressure_unregister_event(struct cgroup_subsys_state *css,
> +				 struct cftype *cft,
>  				 struct eventfd_ctx *eventfd)
>  {
> -	struct vmpressure *vmpr = cg_to_vmpressure(cg);
> +	struct vmpressure *vmpr = css_to_vmpressure(css);
>  	struct vmpressure_event *ev;
>  
>  	mutex_lock(&vmpr->events_lock);
> -- 
> 1.8.3.1
> 

-- 
Michal Hocko
SUSE Labs
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