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Commit 35cf0836 authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: rename cgroup_css_from_dir() to css_from_dir() and update its syntax 



cgroup_css_from_dir() will grow another user.  In preparation, make
the following changes.

* All css functions are prefixed with just "css_", rename it to
  css_from_dir().

* Take dentry * instead of file * as dentry is what ultimately
  identifies a cgroup and file may not always be available.  Note that
  the function now checkes whether @dentry->d_inode is NULL as the
  caller now may specify a negative dentry.

* Make it take cgroup_subsys * instead of integer subsys_id.  This
  simplifies the function and allows specifying no subsystem for
  cgroup->dummy_css.

* Make return section a bit less verbose.

This patch doesn't introduce any behavior changes.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
Acked-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
parent 6e6eab0e

include/linux/cgroup.h

+2 −1
Original line number Diff line number Diff line
@@ -903,7 +903,8 @@ bool css_is_ancestor(struct cgroup_subsys_state *cg, 


/* Get id and depth of css */

unsigned short css_id(struct cgroup_subsys_state *css);

struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id);

struct cgroup_subsys_state *css_from_dir(struct dentry *dentry,

					 struct cgroup_subsys *ss);



#else /* !CONFIG_CGROUPS */

kernel/cgroup.c

+10 −16
Original line number Diff line number Diff line
@@ -5700,34 +5700,28 @@ struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id) 
EXPORT_SYMBOL_GPL(css_lookup);



/**

 * cgroup_css_from_dir - get corresponding css from file open on cgroup dir

 * @f: directory file of interest

 * @id: subsystem id of interest

 * css_from_dir - get corresponding css from the dentry of a cgroup dir

 * @dentry: directory dentry of interest

 * @ss: subsystem of interest

 *

 * Must be called under RCU read lock.  The caller is responsible for

 * pinning the returned css if it needs to be accessed outside the RCU

 * critical section.

 */

struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id)

struct cgroup_subsys_state *css_from_dir(struct dentry *dentry,

					 struct cgroup_subsys *ss)

{

	struct cgroup *cgrp;

	struct inode *inode;

	struct cgroup_subsys_state *css;



	WARN_ON_ONCE(!rcu_read_lock_held());



	inode = file_inode(f);

	/* check in cgroup filesystem dir */

	if (inode->i_op != &cgroup_dir_inode_operations)

	/* is @dentry a cgroup dir? */

	if (!dentry->d_inode ||

	    dentry->d_inode->i_op != &cgroup_dir_inode_operations)

		return ERR_PTR(-EBADF);



	if (id < 0 || id >= CGROUP_SUBSYS_COUNT)

		return ERR_PTR(-EINVAL);



	/* get cgroup */

	cgrp = __d_cgrp(f->f_dentry);

	css = cgroup_css(cgrp, id);

	return css ? css : ERR_PTR(-ENOENT);

	cgrp = __d_cgrp(dentry);

	return cgroup_css(cgrp, ss->subsys_id) ?: ERR_PTR(-ENOENT);

}



/**

kernel/events/core.c

+1 −1
Original line number Diff line number Diff line
@@ -593,7 +593,7 @@ static inline int perf_cgroup_connect(int fd, struct perf_event *event, 


	rcu_read_lock();



	css = cgroup_css_from_dir(f.file, perf_subsys_id);

	css = css_from_dir(f.file->f_dentry, &perf_subsys);

	if (IS_ERR(css)) {

		ret = PTR_ERR(css);

		goto out;