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Commit b9777cf8 authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: unexport locking interface and cgroup_attach_task() 



Now that all external cgroup_lock() users are gone, we can finally
unexport the locking interface and prevent future abuse of
cgroup_mutex.

Make cgroup_[un]lock() and cgroup_lock_live_group() static.  Also,
cgroup_attach_task() doesn't have any user left and can't be used
without locking interface anyway.  Make it static too.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
parent 7ae1bad9

include/linux/cgroup.h

+0 −5
Original line number Diff line number Diff line
@@ -30,10 +30,7 @@ struct css_id; 


extern int cgroup_init_early(void);

extern int cgroup_init(void);

extern void cgroup_lock(void);

extern int cgroup_lock_is_held(void);

extern bool cgroup_lock_live_group(struct cgroup *cgrp);

extern void cgroup_unlock(void);

extern void cgroup_fork(struct task_struct *p);

extern void cgroup_post_fork(struct task_struct *p);

extern void cgroup_exit(struct task_struct *p, int run_callbacks);
@@ -693,8 +690,6 @@ struct task_struct *cgroup_iter_next(struct cgroup *cgrp, 
					struct cgroup_iter *it);

void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it);

int cgroup_scan_tasks(struct cgroup_scanner *scan);

int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk,

		       bool threadgroup);

int cgroup_attach_task_all(struct task_struct *from, struct task_struct *);

int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from);

kernel/cgroup.c

+3 −6
Original line number Diff line number Diff line
@@ -336,7 +336,7 @@ static inline struct cftype *__d_cft(struct dentry *dentry) 
 * On success, returns true; the lock should be later released with

 * cgroup_unlock(). On failure returns false with no lock held.

 */

bool cgroup_lock_live_group(struct cgroup *cgrp)

static bool cgroup_lock_live_group(struct cgroup *cgrp)

{

	mutex_lock(&cgroup_mutex);

	if (cgroup_is_removed(cgrp)) {
@@ -345,7 +345,6 @@ bool cgroup_lock_live_group(struct cgroup *cgrp) 
	}

	return true;

}

EXPORT_SYMBOL_GPL(cgroup_lock_live_group);



/* the list of cgroups eligible for automatic release. Protected by

 * release_list_lock */
@@ -824,22 +823,20 @@ static struct cgroup *task_cgroup_from_root(struct task_struct *task, 
 * cgroup_lock - lock out any changes to cgroup structures

 *

 */

void cgroup_lock(void)

static void cgroup_lock(void)

{

	mutex_lock(&cgroup_mutex);

}

EXPORT_SYMBOL_GPL(cgroup_lock);



/**

 * cgroup_unlock - release lock on cgroup changes

 *

 * Undo the lock taken in a previous cgroup_lock() call.

 */

void cgroup_unlock(void)

static void cgroup_unlock(void)

{

	mutex_unlock(&cgroup_mutex);

}

EXPORT_SYMBOL_GPL(cgroup_unlock);



/*

 * A couple of forward declarations required, due to cyclic reference loop: