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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: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
This commit is contained in:
Tejun Heo 2013-12-05 12:28:04 -05:00
parent 896f519963
commit 5d22444f42
1 changed files with 30 additions and 36 deletions
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66
kernel/cgroup.c
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@ -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,
},