[PATCH 3/4] chardev: Don't use i_devices inode field

From: Jan Kara
Date: Tue Nov 04 2014 - 05:29:53 EST


Now that character device can be freed only after all inodes referencing
it through i_cdev are gone, we can remove all the tracking of inodes
pointing to a character device.

Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
fs/char_dev.c | 22 +---------------------
include/linux/cdev.h | 1 -
2 files changed, 1 insertion(+), 22 deletions(-)

diff --git a/fs/char_dev.c b/fs/char_dev.c
index 518b3016ab92..4c155efc1556 100644
--- a/fs/char_dev.c
+++ b/fs/char_dev.c
@@ -390,7 +390,6 @@ static int chrdev_open(struct inode *inode, struct file *filp)
if (!p) {
/* Use reference from kobj_lookup for i_cdev ref */
inode->i_cdev = p = new;
- list_add(&inode->i_devices, &p->list);
new = NULL;
}
}
@@ -425,7 +424,6 @@ void cd_forget(struct inode *inode)
struct cdev *to_put;

spin_lock(&cdev_lock);
- list_del_init(&inode->i_devices);
to_put = inode->i_cdev;
inode->i_cdev = NULL;
spin_unlock(&cdev_lock);
@@ -433,18 +431,6 @@ void cd_forget(struct inode *inode)
cdev_put(to_put);
}

-static void cdev_purge(struct cdev *cdev)
-{
- spin_lock(&cdev_lock);
- while (!list_empty(&cdev->list)) {
- struct inode *inode;
- inode = container_of(cdev->list.next, struct inode, i_devices);
- list_del_init(&inode->i_devices);
- inode->i_cdev = NULL;
- }
- spin_unlock(&cdev_lock);
-}
-
/*
* Dummy default file-operations: the only thing this does
* is contain the open that then fills in the correct operations
@@ -515,10 +501,8 @@ void cdev_del(struct cdev *p)

static void cdev_default_release(struct kobject *kobj)
{
- struct cdev *p = container_of(kobj, struct cdev, kobj);
struct kobject *parent = kobj->parent;

- cdev_purge(p);
kobject_put(parent);
}

@@ -527,7 +511,6 @@ static void cdev_dynamic_release(struct kobject *kobj)
struct cdev *p = container_of(kobj, struct cdev, kobj);
struct kobject *parent = kobj->parent;

- cdev_purge(p);
kfree(p);
kobject_put(parent);
}
@@ -548,10 +531,8 @@ static struct kobj_type ktype_cdev_dynamic = {
struct cdev *cdev_alloc(void)
{
struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL);
- if (p) {
- INIT_LIST_HEAD(&p->list);
+ if (p)
kobject_init(&p->kobj, &ktype_cdev_dynamic);
- }
return p;
}

@@ -566,7 +547,6 @@ struct cdev *cdev_alloc(void)
void cdev_init(struct cdev *cdev, const struct file_operations *fops)
{
memset(cdev, 0, sizeof *cdev);
- INIT_LIST_HEAD(&cdev->list);
kobject_init(&cdev->kobj, &ktype_cdev_default);
cdev->ops = fops;
}
diff --git a/include/linux/cdev.h b/include/linux/cdev.h
index fb4591977b03..fe00138b5106 100644
--- a/include/linux/cdev.h
+++ b/include/linux/cdev.h
@@ -13,7 +13,6 @@ struct cdev {
struct kobject kobj;
struct module *owner;
const struct file_operations *ops;
- struct list_head list;
dev_t dev;
unsigned int count;
};
--
1.8.1.4

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