| /** |
| * 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) |
