Messages in this thread |  | | | Subject | [Bug? Report] kref problem | | From | "Artem B. Bityutskiy" <> | | Date | Thu, 16 Mar 2006 14:41:19 +0300 |
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Hello Greg,
I've hit on a kref problem Please, glance at the attached test module.
The idea of the test is to create 2 kobjects (a and b), create dir A with kobject A, and dir B with kobject B, so that A is B's parent. E.g., we'll have /sys/A/B.
I see the following output of the test:
a inited, kref 1 b inited, kref 1 dir A created, A kref 1, B kref 1 dir B created, A kref 1, B kref 1 b_release a_release kobj B put, A kref 0, B kref 0 kobj A put, A kref -1, B kref 0
So what I don't like is this "A kref -1". Why when I remove directory B, kobj a is released? For me it looks like a bug.
The kernel is 2.6.16-rc6.
Thanks.
-- Best Regards, Artem B. Bityuckiy, St.-Petersburg, Russia. #include <linux/kernel.h> #include <linux/init.h> #include <linux/module.h> #include <linux/kobject.h> #include <linux/stat.h>
static void a_release(struct kobject *kobj);
static struct kobj_type a_ktype = { .release = a_release }; static void b_release(struct kobject *kobj);
static struct kobj_type b_ktype = { .release = b_release }; struct my_obj_a { struct kobject kobj; } a; struct my_obj_b { struct kobject kobj; } b; static __init int test_init(void) { int err; kobject_init(&a.kobj); a.kobj.ktype = &a_ktype; err = kobject_set_name(&a.kobj, "A"); if (err) return err; printk("a inited, kref %d\n", atomic_read(&a.kobj.kref.refcount)); kobject_init(&b.kobj); b.kobj.ktype = &b_ktype; b.kobj.parent = &a.kobj; err = kobject_set_name(&b.kobj, "B"); if (err) goto out_a; printk("b inited, kref %d\n", atomic_read(&b.kobj.kref.refcount)); err = sysfs_create_dir(&a.kobj); if (err) goto out_b; printk("dir A created, A kref %d, B kref %d\n", atomic_read(&a.kobj.kref.refcount), atomic_read(&b.kobj.kref.refcount)); err = sysfs_create_dir(&b.kobj); if (err) goto out_a_dir; printk("dir B created, A kref %d, B kref %d\n", atomic_read(&a.kobj.kref.refcount), atomic_read(&b.kobj.kref.refcount)); kobject_put(&b.kobj); printk("kobj B put, A kref %d, B kref %d\n", atomic_read(&a.kobj.kref.refcount), atomic_read(&b.kobj.kref.refcount));
kobject_put(&a.kobj); printk("kobj A put, A kref %d, B kref %d\n", atomic_read(&a.kobj.kref.refcount), atomic_read(&b.kobj.kref.refcount));
return 0;
out_a_dir: sysfs_remove_dir(&a.kobj); out_b: kobject_put(&b.kobj); out_a: kobject_put(&a.kobj); return err; } module_init(test_init); static void a_release(struct kobject *kobj) { struct my_obj_a *a; printk("%s\n", __FUNCTION__); a = container_of(kobj, struct my_obj_a, kobj); sysfs_remove_dir(&a->kobj); } static void b_release(struct kobject *kobj) { struct my_obj_b *b; printk("%s\n", __FUNCTION__); b = container_of(kobj, struct my_obj_b, kobj); sysfs_remove_dir(&b->kobj); } static __exit void test_exit(void) { } module_exit(test_exit); MODULE_VERSION("1"); MODULE_DESCRIPTION("kref test"); MODULE_AUTHOR("Artem B. Bityutskiy"); MODULE_LICENSE("GPL");
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