cgroup: Rename cgroup lifecycle hooks to cgroup_task_*()

The current names cgroup_exit(), cgroup_release(), and cgroup_free() are
confusing because they look like they're operating on cgroups themselves when
they're actually task lifecycle hooks. For example, cgroup_init() initializes
the cgroup subsystem while cgroup_exit() is a task exit notification to
cgroup. Rename them to cgroup_task_exit(), cgroup_task_release(), and
cgroup_task_free() to make it clear that these operate on tasks.

Cc: Dan Schatzberg <dschatzberg@meta.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Chen Ridong <chenridong@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

Author: htejun

include/linux/cgroup.h

@@ -137,9 +137,9 @@ extern void cgroup_cancel_fork(struct task_struct *p,
 			       struct kernel_clone_args *kargs);
 extern void cgroup_post_fork(struct task_struct *p,
 			     struct kernel_clone_args *kargs);
-void cgroup_exit(struct task_struct *p);
-void cgroup_release(struct task_struct *p);
-void cgroup_free(struct task_struct *p);
+void cgroup_task_exit(struct task_struct *p);
+void cgroup_task_release(struct task_struct *p);
+void cgroup_task_free(struct task_struct *p);
 
 int cgroup_init_early(void);
 int cgroup_init(void);
@@ -680,9 +680,9 @@ static inline void cgroup_cancel_fork(struct task_struct *p,
 				      struct kernel_clone_args *kargs) {}
 static inline void cgroup_post_fork(struct task_struct *p,
 				    struct kernel_clone_args *kargs) {}
-static inline void cgroup_exit(struct task_struct *p) {}
-static inline void cgroup_release(struct task_struct *p) {}
-static inline void cgroup_free(struct task_struct *p) {}
+static inline void cgroup_task_exit(struct task_struct *p) {}
+static inline void cgroup_task_release(struct task_struct *p) {}
+static inline void cgroup_task_free(struct task_struct *p) {}
 
 static inline int cgroup_init_early(void) { return 0; }
 static inline int cgroup_init(void) { return 0; }

kernel/cgroup/cgroup.c

@@ -944,7 +944,8 @@ static void css_set_move_task(struct task_struct *task,
 		/*
 		 * We are synchronized through cgroup_threadgroup_rwsem
 		 * against PF_EXITING setting such that we can't race
-		 * against cgroup_exit()/cgroup_free() dropping the css_set.
+		 * against cgroup_task_exit()/cgroup_task_free() dropping
+		 * the css_set.
 		 */
 		WARN_ON_ONCE(task->flags & PF_EXITING);
 
@@ -6972,13 +6973,13 @@ void cgroup_post_fork(struct task_struct *child,
 }
 
 /**
- * cgroup_exit - detach cgroup from exiting task
+ * cgroup_task_exit - detach cgroup from exiting task
  * @tsk: pointer to task_struct of exiting process
  *
  * Description: Detach cgroup from @tsk.
  *
  */
-void cgroup_exit(struct task_struct *tsk)
+void cgroup_task_exit(struct task_struct *tsk)
 {
 	struct cgroup_subsys *ss;
 	struct css_set *cset;
@@ -7010,7 +7011,7 @@ void cgroup_exit(struct task_struct *tsk)
 	} while_each_subsys_mask();
 }
 
-void cgroup_release(struct task_struct *task)
+void cgroup_task_release(struct task_struct *task)
 {
 	struct cgroup_subsys *ss;
 	int ssid;
@@ -7027,7 +7028,7 @@ void cgroup_release(struct task_struct *task)
 	}
 }
 
-void cgroup_free(struct task_struct *task)
+void cgroup_task_free(struct task_struct *task)
 {
 	struct css_set *cset = task_css_set(task);
 	put_css_set(cset);

kernel/exit.c

@@ -257,7 +257,7 @@ void release_task(struct task_struct *p)
 	rcu_read_unlock();
 
 	pidfs_exit(p);
-	cgroup_release(p);
+	cgroup_task_release(p);
 
 	/* Retrieve @thread_pid before __unhash_process() may set it to NULL. */
 	thread_pid = task_pid(p);
@@ -967,7 +967,7 @@ void __noreturn do_exit(long code)
 	exit_thread(tsk);
 
 	sched_autogroup_exit_task(tsk);
-	cgroup_exit(tsk);
+	cgroup_task_exit(tsk);
 
 	/*
 	 * FIXME: do that only when needed, using sched_exit tracepoint

kernel/fork.c

@@ -738,7 +738,7 @@ void __put_task_struct(struct task_struct *tsk)
 	unwind_task_free(tsk);
 	sched_ext_free(tsk);
 	io_uring_free(tsk);
-	cgroup_free(tsk);
+	cgroup_task_free(tsk);
 	task_numa_free(tsk, true);
 	security_task_free(tsk);
 	exit_creds(tsk);

kernel/sched/autogroup.c

@@ -178,8 +178,8 @@ autogroup_move_group(struct task_struct *p, struct autogroup *ag)
 	 * this process can already run with task_group() == prev->tg or we can
 	 * race with cgroup code which can read autogroup = prev under rq->lock.
 	 * In the latter case for_each_thread() can not miss a migrating thread,
-	 * cpu_cgroup_attach() must not be possible after cgroup_exit() and it
-	 * can't be removed from thread list, we hold ->siglock.
+	 * cpu_cgroup_attach() must not be possible after cgroup_task_exit()
+	 * and it can't be removed from thread list, we hold ->siglock.
 	 *
 	 * If an exiting thread was already removed from thread list we rely on
 	 * sched_autogroup_exit_task().