diff options
Diffstat (limited to 'include/linux/cgroup_refcnt.h')
-rw-r--r-- | include/linux/cgroup_refcnt.h | 96 |
1 files changed, 96 insertions, 0 deletions
diff --git a/include/linux/cgroup_refcnt.h b/include/linux/cgroup_refcnt.h new file mode 100644 index 000000000000..2eea0a69ecfc --- /dev/null +++ b/include/linux/cgroup_refcnt.h @@ -0,0 +1,96 @@ +/** + * css_get - obtain a reference on the specified css + * @css: target css + * + * The caller must already have a reference. + */ +CGROUP_REF_FN_ATTRS +void css_get(struct cgroup_subsys_state *css) +{ + if (!(css->flags & CSS_NO_REF)) + percpu_ref_get(&css->refcnt); +} +CGROUP_REF_EXPORT(css_get) + +/** + * css_get_many - obtain references on the specified css + * @css: target css + * @n: number of references to get + * + * The caller must already have a reference. + */ +CGROUP_REF_FN_ATTRS +void css_get_many(struct cgroup_subsys_state *css, unsigned int n) +{ + if (!(css->flags & CSS_NO_REF)) + percpu_ref_get_many(&css->refcnt, n); +} +CGROUP_REF_EXPORT(css_get_many) + +/** + * css_tryget - try to obtain a reference on the specified css + * @css: target css + * + * Obtain a reference on @css unless it already has reached zero and is + * being released. This function doesn't care whether @css is on or + * offline. 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. + */ +CGROUP_REF_FN_ATTRS +bool css_tryget(struct cgroup_subsys_state *css) +{ + if (!(css->flags & CSS_NO_REF)) + return percpu_ref_tryget(&css->refcnt); + return true; +} +CGROUP_REF_EXPORT(css_tryget) + +/** + * css_tryget_online - try to obtain a reference on the specified css if online + * @css: target css + * + * Obtain a reference on @css if it's online. 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. + */ +CGROUP_REF_FN_ATTRS +bool css_tryget_online(struct cgroup_subsys_state *css) +{ + if (!(css->flags & CSS_NO_REF)) + return percpu_ref_tryget_live(&css->refcnt); + return true; +} +CGROUP_REF_EXPORT(css_tryget_online) + +/** + * css_put - put a css reference + * @css: target css + * + * Put a reference obtained via css_get() and css_tryget_online(). + */ +CGROUP_REF_FN_ATTRS +void css_put(struct cgroup_subsys_state *css) +{ + if (!(css->flags & CSS_NO_REF)) + percpu_ref_put(&css->refcnt); +} +CGROUP_REF_EXPORT(css_put) + +/** + * css_put_many - put css references + * @css: target css + * @n: number of references to put + * + * Put references obtained via css_get() and css_tryget_online(). + */ +CGROUP_REF_FN_ATTRS +void css_put_many(struct cgroup_subsys_state *css, unsigned int n) +{ + if (!(css->flags & CSS_NO_REF)) + percpu_ref_put_many(&css->refcnt, n); +} +CGROUP_REF_EXPORT(css_put_many) |