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Commit 5d22444f authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: generalize cgroup_pidlist_open_file 



In preparation of conversion to kernfs, cgroup file handling is
updated so that it can be easily mapped to kernfs.  This patch renames
cgroup_pidlist_open_file to cgroup_open_file and updates it so that it
only contains a field to identify the specific file, ->cfe, and an
opaque ->priv pointer.  When cgroup is converted to kernfs, this will
be replaced by kernfs_open_file which contains about the same
information.

As whether the file is "cgroup.procs" or "tasks" should now be
determined from cgroup_open_file->cfe, the cftype->private for the two
files now carry the file type and cgroup_pidlist_start() reads the
type through cfe->type->private.  This makes the distinction between
cgroup_tasks_open() and cgroup_procs_open() unnecessary.
cgroup_pidlist_open() is now directly used as the open method.

This patch doesn't make any behavior changes.

v2: Refreshed on top of the updated "cgroup: introduce struct
    cgroup_pidlist_open_file".

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
parent 896f5199

kernel/cgroup.c

+30 −36
Original line number Diff line number Diff line
@@ -3369,10 +3369,9 @@ struct cgroup_pidlist { 
};



/* seq_file->private points to the following */

struct cgroup_pidlist_open_file {

	enum cgroup_filetype		type;

	struct cgroup			*cgrp;

	struct cgroup_pidlist		*pidlist;

struct cgroup_open_file {

	struct cfent			*cfe;

	void				*priv;

};



/*
@@ -3689,33 +3688,35 @@ static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) 
	 * after a seek to the start). Use a binary-search to find the

	 * next pid to display, if any

	 */

	struct cgroup_pidlist_open_file *of = s->private;

	struct cgroup *cgrp = of->cgrp;

	struct cgroup_open_file *of = s->private;

	struct cgroup *cgrp = of->cfe->css->cgroup;

	struct cgroup_pidlist *l;

	enum cgroup_filetype type = of->cfe->type->private;

	int index = 0, pid = *pos;

	int *iter, ret;



	mutex_lock(&cgrp->pidlist_mutex);



	/*

	 * !NULL @of->pidlist indicates that this isn't the first start()

	 * !NULL @of->priv indicates that this isn't the first start()

	 * after open.  If the matching pidlist is around, we can use that.

	 * Look for it.  Note that @of->pidlist can't be used directly.  It

	 * Look for it.  Note that @of->priv can't be used directly.  It

	 * could already have been destroyed.

	 */

	if (of->pidlist)

		of->pidlist = cgroup_pidlist_find(cgrp, of->type);

	if (of->priv)

		of->priv = cgroup_pidlist_find(cgrp, type);



	/*

	 * Either this is the first start() after open or the matching

	 * pidlist has been destroyed inbetween.  Create a new one.

	 */

	if (!of->pidlist) {

		ret = pidlist_array_load(of->cgrp, of->type, &of->pidlist);

	if (!of->priv) {

		ret = pidlist_array_load(cgrp, type,

					 (struct cgroup_pidlist **)&of->priv);

		if (ret)

			return ERR_PTR(ret);

	}

	l = of->pidlist;

	l = of->priv;



	if (pid) {

		int end = l->length;
@@ -3742,19 +3743,19 @@ static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) 


static void cgroup_pidlist_stop(struct seq_file *s, void *v)

{

	struct cgroup_pidlist_open_file *of = s->private;

	struct cgroup_open_file *of = s->private;

	struct cgroup_pidlist *l = of->priv;



	if (of->pidlist)

		mod_delayed_work(cgroup_pidlist_destroy_wq,

				 &of->pidlist->destroy_dwork,

	if (l)

		mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork,

				 CGROUP_PIDLIST_DESTROY_DELAY);

	mutex_unlock(&of->cgrp->pidlist_mutex);

	mutex_unlock(&of->cfe->css->cgroup->pidlist_mutex);

}



static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos)

{

	struct cgroup_pidlist_open_file *of = s->private;

	struct cgroup_pidlist *l = of->pidlist;

	struct cgroup_open_file *of = s->private;

	struct cgroup_pidlist *l = of->priv;

	pid_t *p = v;

	pid_t *end = l->list + l->length;

	/*
@@ -3765,7 +3766,7 @@ static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) 
	if (p >= end) {

		return NULL;

	} else {

		*pos = cgroup_pid_fry(of->cgrp, *p);

		*pos = cgroup_pid_fry(of->cfe->css->cgroup, *p);

		return p;

	}

}
@@ -3799,10 +3800,10 @@ static const struct file_operations cgroup_pidlist_operations = { 
 * in the cgroup.

 */

/* helper function for the two below it */

static int cgroup_pidlist_open(struct file *file, enum cgroup_filetype type)

static int cgroup_pidlist_open(struct inode *unused, struct file *file)

{

	struct cgroup *cgrp = __d_cgrp(file->f_dentry->d_parent);

	struct cgroup_pidlist_open_file *of;

	struct cfent *cfe = __d_cfe(file->f_dentry);

	struct cgroup_open_file *of;



	/* configure file information */

	file->f_op = &cgroup_pidlist_operations;
@@ -3812,18 +3813,9 @@ static int cgroup_pidlist_open(struct file *file, enum cgroup_filetype type) 
	if (!of)

		return -ENOMEM;



	of->type = type;

	of->cgrp = cgrp;

	of->cfe = cfe;

	return 0;

}

static int cgroup_tasks_open(struct inode *unused, struct file *file)

{

	return cgroup_pidlist_open(file, CGROUP_FILE_TASKS);

}

static int cgroup_procs_open(struct inode *unused, struct file *file)

{

	return cgroup_pidlist_open(file, CGROUP_FILE_PROCS);

}



static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css,

					 struct cftype *cft)
@@ -3878,7 +3870,8 @@ static int cgroup_clone_children_write(struct cgroup_subsys_state *css, 
static struct cftype cgroup_base_files[] = {

	{

		.name = "cgroup.procs",

		.open = cgroup_procs_open,

		.open = cgroup_pidlist_open,

		.private = CGROUP_FILE_PROCS,

		.write_u64 = cgroup_procs_write,

		.mode = S_IRUGO | S_IWUSR,

	},
@@ -3902,7 +3895,8 @@ static struct cftype cgroup_base_files[] = { 
	{

		.name = "tasks",

		.flags = CFTYPE_INSANE,		/* use "procs" instead */

		.open = cgroup_tasks_open,

		.open = cgroup_pidlist_open,

		.private = CGROUP_FILE_TASKS,

		.write_u64 = cgroup_tasks_write,

		.mode = S_IRUGO | S_IWUSR,

	},