Commit 62236858 authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: introduce struct cgroup_pidlist_open_file 



For pidlist files, seq_file->private pointed to the loaded
cgroup_pidlist; however, pidlist loading is planned to be moved to
cgroup_pidlist_start() for kernfs conversion and seq_file->private
needs to carry more information from open to allow that.

This patch introduces struct cgroup_pidlist_open_file which contains
type, cgrp and pidlist and updates pidlist seq_file->private to point
to it using seq_open_private() and seq_release_private().  Note that
this eventually will be replaced by kernfs_open_file.

While this patch makes more information available to seq_file
operations, they don't use it yet and this patch doesn't introduce any
behavior changes except for allocation of the extra private struct.

v2: use __seq_open_private() instead of seq_open_private() for brevity
    as suggested by Li.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
parent b1a21367

kernel/cgroup.c

+27 −12
Original line number Diff line number Diff line
@@ -3468,6 +3468,13 @@ struct cgroup_pidlist { 
	struct delayed_work destroy_dwork;

};



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

struct cgroup_pidlist_open_file {

	enum cgroup_filetype		type;

	struct cgroup			*cgrp;

	struct cgroup_pidlist		*pidlist;

};



/*

 * The following two functions "fix" the issue where there are more pids

 * than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
@@ -3739,7 +3746,8 @@ 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 *l = s->private;

	struct cgroup_pidlist_open_file *of = s->private;

	struct cgroup_pidlist *l = of->pidlist;

	int index = 0, pid = *pos;

	int *iter;
@@ -3769,13 +3777,15 @@ 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 *l = s->private;

	up_read(&l->rwsem);

	struct cgroup_pidlist_open_file *of = s->private;



	up_read(&of->pidlist->rwsem);

}



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

{

	struct cgroup_pidlist *l = s->private;

	struct cgroup_pidlist_open_file *of = s->private;

	struct cgroup_pidlist *l = of->pidlist;

	pid_t *p = v;

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

	/*
@@ -3820,11 +3830,11 @@ static void cgroup_release_pid_array(struct cgroup_pidlist *l) 


static int cgroup_pidlist_release(struct inode *inode, struct file *file)

{

	struct cgroup_pidlist *l;

	struct cgroup_pidlist_open_file *of;



	l = ((struct seq_file *)file->private_data)->private;

	cgroup_release_pid_array(l);

	return seq_release(inode, file);

	of = ((struct seq_file *)file->private_data)->private;

	cgroup_release_pid_array(of->pidlist);

	return seq_release_private(inode, file);

}



static const struct file_operations cgroup_pidlist_operations = {
@@ -3843,6 +3853,7 @@ static const struct file_operations cgroup_pidlist_operations = { 
static int cgroup_pidlist_open(struct file *file, enum cgroup_filetype type)

{

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

	struct cgroup_pidlist_open_file *of;

	struct cgroup_pidlist *l;

	int retval;
@@ -3853,12 +3864,16 @@ static int cgroup_pidlist_open(struct file *file, enum cgroup_filetype type) 
	/* configure file information */

	file->f_op = &cgroup_pidlist_operations;



	retval = seq_open(file, &cgroup_pidlist_seq_operations);

	if (retval) {

	of = __seq_open_private(file, &cgroup_pidlist_seq_operations,

				sizeof(*of));

	if (!of) {

		cgroup_release_pid_array(l);

		return retval;

		return -ENOMEM;

	}

	((struct seq_file *)file->private_data)->private = l;



	of->type = type;

	of->cgrp = cgrp;

	of->pidlist = l;

	return 0;

}

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

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