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Subject[PATCH RESEND] char_dev: add cdev->release() and convert cdev_alloc() to use it
Add cdev->release() so that cdev can be considered in more involved
object lifetime management. cdev_alloc() used a separate ktype for
auto-free release(). This patch converts it to use cdev->release() so
that there's no need for separate ktype and cdev_init() can be used
for auto-free variant too.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
fs/char_dev.c | 30 +++++++++++++-----------------
include/linux/cdev.h | 1 +
2 files changed, 14 insertions(+), 17 deletions(-)

Index: work/fs/char_dev.c
===================================================================
--- work.orig/fs/char_dev.c
+++ work/fs/char_dev.c
@@ -482,26 +482,22 @@ void cdev_del(struct cdev *p)
}


-static void cdev_default_release(struct kobject *kobj)
+static void cdev_release(struct kobject *kobj)
{
struct cdev *p = container_of(kobj, struct cdev, kobj);
cdev_purge(p);
+ if (p->release)
+ p->release(p);
}

-static void cdev_dynamic_release(struct kobject *kobj)
-{
- struct cdev *p = container_of(kobj, struct cdev, kobj);
- cdev_purge(p);
- kfree(p);
-}
-
-static struct kobj_type ktype_cdev_default = {
- .release = cdev_default_release,
+static struct kobj_type cdev_ktype = {
+ .release = cdev_release,
};

-static struct kobj_type ktype_cdev_dynamic = {
- .release = cdev_dynamic_release,
-};
+static void cdev_alloc_release(struct cdev *cdev)
+{
+ kfree(cdev);
+}

/**
* cdev_alloc() - allocate a cdev structure
@@ -510,10 +506,10 @@ static struct kobj_type ktype_cdev_dynam
*/
struct cdev *cdev_alloc(void)
{
- struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL);
+ struct cdev *p = kmalloc(sizeof(struct cdev), GFP_KERNEL);
if (p) {
- INIT_LIST_HEAD(&p->list);
- kobject_init(&p->kobj, &ktype_cdev_dynamic);
+ cdev_init(p, NULL);
+ p->release = cdev_alloc_release;
}
return p;
}
@@ -530,7 +526,7 @@ void cdev_init(struct cdev *cdev, const
{
memset(cdev, 0, sizeof *cdev);
INIT_LIST_HEAD(&cdev->list);
- kobject_init(&cdev->kobj, &ktype_cdev_default);
+ kobject_init(&cdev->kobj, &cdev_ktype);
cdev->ops = fops;
}

Index: work/include/linux/cdev.h
===================================================================
--- work.orig/include/linux/cdev.h
+++ work/include/linux/cdev.h
@@ -16,6 +16,7 @@ struct cdev {
struct list_head list;
dev_t dev;
unsigned int count;
+ void (*release)(struct cdev *);
};

void cdev_init(struct cdev *, const struct file_operations *);

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