Commit 780de9dd authored by Ingo Molnar's avatar Ingo Molnar
Browse files

sched/headers, cgroups: Remove the threadgroup_change_*() wrappery 



threadgroup_change_begin()/end() is a pointless wrapper around
cgroup_threadgroup_change_begin()/end(), minus a might_sleep()
in the !CONFIG_CGROUPS=y case.

Remove the wrappery, move the might_sleep() (the down_read()
already has a might_sleep() check).

This debloats <linux/sched.h> a bit and simplifies this API.

Update all call sites.

No change in functionality.

Acked-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent f9411ebe

fs/exec.c

+3 −3
Original line number Diff line number Diff line
@@ -1088,7 +1088,7 @@ static int de_thread(struct task_struct *tsk) 
		struct task_struct *leader = tsk->group_leader;



		for (;;) {

			threadgroup_change_begin(tsk);

			cgroup_threadgroup_change_begin(tsk);

			write_lock_irq(&tasklist_lock);

			/*

			 * Do this under tasklist_lock to ensure that
@@ -1099,7 +1099,7 @@ static int de_thread(struct task_struct *tsk) 
				break;

			__set_current_state(TASK_KILLABLE);

			write_unlock_irq(&tasklist_lock);

			threadgroup_change_end(tsk);

			cgroup_threadgroup_change_end(tsk);

			schedule();

			if (unlikely(__fatal_signal_pending(tsk)))

				goto killed;
@@ -1157,7 +1157,7 @@ static int de_thread(struct task_struct *tsk) 
		if (unlikely(leader->ptrace))

			__wake_up_parent(leader, leader->parent);

		write_unlock_irq(&tasklist_lock);

		threadgroup_change_end(tsk);

		cgroup_threadgroup_change_end(tsk);



		release_task(leader);

	}

include/linux/cgroup-defs.h

+8 −5
Original line number Diff line number Diff line
@@ -531,8 +531,8 @@ extern struct percpu_rw_semaphore cgroup_threadgroup_rwsem; 
 * cgroup_threadgroup_change_begin - threadgroup exclusion for cgroups

 * @tsk: target task

 *

 * Called from threadgroup_change_begin() and allows cgroup operations to

 * synchronize against threadgroup changes using a percpu_rw_semaphore.

 * Allows cgroup operations to synchronize against threadgroup changes

 * using a percpu_rw_semaphore.

 */

static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk)

{
@@ -543,8 +543,7 @@ static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk) 
 * cgroup_threadgroup_change_end - threadgroup exclusion for cgroups

 * @tsk: target task

 *

 * Called from threadgroup_change_end().  Counterpart of

 * cgroup_threadcgroup_change_begin().

 * Counterpart of cgroup_threadcgroup_change_begin().

 */

static inline void cgroup_threadgroup_change_end(struct task_struct *tsk)

{
@@ -555,7 +554,11 @@ static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) 


#define CGROUP_SUBSYS_COUNT 0



static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk) {}

static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk)

{

	might_sleep();

}



static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) {}



#endif	/* CONFIG_CGROUPS */

include/linux/sched.h

+0 −28
Original line number Diff line number Diff line
@@ -3162,34 +3162,6 @@ static inline void unlock_task_sighand(struct task_struct *tsk, 
	spin_unlock_irqrestore(&tsk->sighand->siglock, *flags);

}



/**

 * threadgroup_change_begin - mark the beginning of changes to a threadgroup

 * @tsk: task causing the changes

 *

 * All operations which modify a threadgroup - a new thread joining the

 * group, death of a member thread (the assertion of PF_EXITING) and

 * exec(2) dethreading the process and replacing the leader - are wrapped

 * by threadgroup_change_{begin|end}().  This is to provide a place which

 * subsystems needing threadgroup stability can hook into for

 * synchronization.

 */

static inline void threadgroup_change_begin(struct task_struct *tsk)

{

	might_sleep();

	cgroup_threadgroup_change_begin(tsk);

}



/**

 * threadgroup_change_end - mark the end of changes to a threadgroup

 * @tsk: task causing the changes

 *

 * See threadgroup_change_begin().

 */

static inline void threadgroup_change_end(struct task_struct *tsk)

{

	cgroup_threadgroup_change_end(tsk);

}



#ifdef CONFIG_THREAD_INFO_IN_TASK



static inline struct thread_info *task_thread_info(struct task_struct *task)

kernel/cgroup/pids.c

+1 −1
Original line number Diff line number Diff line
@@ -214,7 +214,7 @@ static void pids_cancel_attach(struct cgroup_taskset *tset) 


/*

 * task_css_check(true) in pids_can_fork() and pids_cancel_fork() relies

 * on threadgroup_change_begin() held by the copy_process().

 * on cgroup_threadgroup_change_begin() held by the copy_process().

 */

static int pids_can_fork(struct task_struct *task)

{

kernel/fork.c

+3 −3
Original line number Diff line number Diff line
@@ -1746,7 +1746,7 @@ static __latent_entropy struct task_struct *copy_process( 
	INIT_LIST_HEAD(&p->thread_group);

	p->task_works = NULL;



	threadgroup_change_begin(current);

	cgroup_threadgroup_change_begin(current);

	/*

	 * Ensure that the cgroup subsystem policies allow the new process to be

	 * forked. It should be noted the the new process's css_set can be changed
@@ -1843,7 +1843,7 @@ static __latent_entropy struct task_struct *copy_process( 


	proc_fork_connector(p);

	cgroup_post_fork(p);

	threadgroup_change_end(current);

	cgroup_threadgroup_change_end(current);

	perf_event_fork(p);



	trace_task_newtask(p, clone_flags);
@@ -1854,7 +1854,7 @@ static __latent_entropy struct task_struct *copy_process( 
bad_fork_cancel_cgroup:

	cgroup_cancel_fork(p);

bad_fork_free_pid:

	threadgroup_change_end(current);

	cgroup_threadgroup_change_end(current);

	if (pid != &init_struct_pid)

		free_pid(pid);

bad_fork_cleanup_thread:

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