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Commit 5de0107e authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: clean up css_[try]get() and css_put() 



* __css_get() isn't used by anyone.  Fold it into css_get().

* Add proper function comments to all css reference functions.

This patch is purely cosmetic.

v2: Typo fix as per Li.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
parent f4f4be2b

include/linux/cgroup.h

+24 −24
Original line number Diff line number Diff line
@@ -94,33 +94,31 @@ enum { 
	CSS_ONLINE	= (1 << 1), /* between ->css_online() and ->css_offline() */

};



/* Caller must verify that the css is not for root cgroup */

static inline void __css_get(struct cgroup_subsys_state *css, int count)

{

	atomic_add(count, &css->refcnt);

}



/*

 * Call css_get() to hold a reference on the css; it can be used

 * for a reference obtained via:

 * - an existing ref-counted reference to the css

 * - task->cgroups for a locked task

/**

 * css_get - obtain a reference on the specified css

 * @css: target css

 *

 * The caller must already have a reference.

 */



static inline void css_get(struct cgroup_subsys_state *css)

{

	/* We don't need to reference count the root state */

	if (!(css->flags & CSS_ROOT))

		__css_get(css, 1);

		atomic_inc(&css->refcnt);

}



/*

 * Call css_tryget() to take a reference on a css if your existing

 * (known-valid) reference isn't already ref-counted. Returns false if

 * the css has been destroyed.

 */



extern bool __css_tryget(struct cgroup_subsys_state *css);



/**

 * css_tryget - try to obtain a reference on the specified css

 * @css: target css

 *

 * Obtain a reference on @css if it's alive.  The caller naturally needs to

 * ensure that @css is accessible but doesn't have to be holding a

 * reference on it - IOW, RCU protected access is good enough for this

 * function.  Returns %true if a reference count was successfully obtained;

 * %false otherwise.

 */

static inline bool css_tryget(struct cgroup_subsys_state *css)

{

	if (css->flags & CSS_ROOT)
@@ -128,12 +126,14 @@ static inline bool css_tryget(struct cgroup_subsys_state *css) 
	return __css_tryget(css);

}



/*

 * css_put() should be called to release a reference taken by

 * css_get() or css_tryget()

 */



extern void __css_put(struct cgroup_subsys_state *css);



/**

 * css_put - put a css reference

 * @css: target css

 *

 * Put a reference obtained via css_get() and css_tryget().

 */

static inline void css_put(struct cgroup_subsys_state *css)

{

	if (!(css->flags & CSS_ROOT))