Re: [PATCH] kobject_set_name_vargs memory leak

From: Eric W. Biederman
Date: Sun Jun 28 2009 - 08:07:31 EST

Kay Sievers <kay.sievers@xxxxxxxx> writes:

> On Sat, 2009-06-27 at 12:39 +0300, Sergey Senozhatsky wrote:
>
>> > >> Or something along those lines, I can't remember the exact reasoning
>> > >> this early in the morning.
>> > >>
>> > >> Kay, do you remember?
>
> Hmm, yes, I think there was only something to work around during the
> transition from the static name array, which is gone now. At least I
> can't see anything we need to care about with the current code.
>
>> Sorry, correct one.
>>
>> diff --git a/lib/kobject.c b/lib/kobject.c
>> index b512b74..3ab224b 100644
>> --- a/lib/kobject.c
>> +++ b/lib/kobject.c
>> @@ -215,7 +215,6 @@ static int kobject_add_internal(struct kobject *kobj)
>> int kobject_set_name_vargs(struct kobject *kobj, const char *fmt,
>> va_list vargs)
>> {
>> - const char *old_name = kobj->name;
>
> I guess, that would leak an allocated name, when it is set several times
> in a row? Something like this?

But setting a kobject's name several times in a row is a bug. You
need to call kobject_rename if you are going to change the name.

So how about we fix the driver core not to do that. Stop treating fmt
as a flag, and make it clear kobject_add should not be passed a name.

I really hate DWIM functions there is no maintaining them.

Something like this patch:

block/blk-sysfs.c | 6 ++++-
block/elevator.c | 4 ++-
drivers/base/core.c | 10 ++++++---
drivers/firmware/memmap.c | 3 +-
drivers/md/md.c | 5 +++-
drivers/net/iseries_veth.c | 4 +--
drivers/uio/uio.c | 9 +++-----
include/linux/kobject.h | 3 --
lib/kobject.c | 46 ++++++++++++++-------------------------------
9 files changed, 43 insertions(+), 47 deletions(-)

diff --git a/lib/kobject.c b/lib/kobject.c
index b512b74..92da396 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -215,11 +215,9 @@ static int kobject_add_internal(struct kobject *kobj)
int kobject_set_name_vargs(struct kobject *kobj, const char *fmt,
va_list vargs)
{
- const char *old_name = kobj->name;
char *s;

- if (kobj->name && !fmt)
- return 0;
+ BUG_ON(kobj->name);

kobj->name = kvasprintf(GFP_KERNEL, fmt, vargs);
if (!kobj->name)
@@ -229,7 +227,6 @@ int kobject_set_name_vargs(struct kobject *kobj, const char *fmt,
while ((s = strchr(kobj->name, '/')))
s[0] = '!';

- kfree(old_name);
return 0;
}

@@ -296,20 +293,6 @@ error:
}
EXPORT_SYMBOL(kobject_init);

-static int kobject_add_varg(struct kobject *kobj, struct kobject *parent,
- const char *fmt, va_list vargs)
-{
- int retval;
-
- retval = kobject_set_name_vargs(kobj, fmt, vargs);
- if (retval) {
- printk(KERN_ERR "kobject: can not set name properly!\n");
- return retval;
- }
- kobj->parent = parent;
- return kobject_add_internal(kobj);
-}
-
/**
* kobject_add - the main kobject add function
* @kobj: the kobject to add
@@ -335,15 +318,14 @@ static int kobject_add_varg(struct kobject *kobj, struct kobject *parent,
* kobject_uevent() with the UEVENT_ADD parameter to ensure that
* userspace is properly notified of this kobject's creation.
*/
-int kobject_add(struct kobject *kobj, struct kobject *parent,
- const char *fmt, ...)
+int kobject_add(struct kobject *kobj, struct kobject *parent)
{
- va_list args;
- int retval;
-
if (!kobj)
return -EINVAL;

+ if (!kobj->name)
+ return -EINVAL;
+
if (!kobj->state_initialized) {
printk(KERN_ERR "kobject '%s' (%p): tried to add an "
"uninitialized object, something is seriously wrong.\n",
@@ -351,11 +333,8 @@ int kobject_add(struct kobject *kobj, struct kobject *parent,
dump_stack();
return -EINVAL;
}
- va_start(args, fmt);
- retval = kobject_add_varg(kobj, parent, fmt, args);
- va_end(args);
-
- return retval;
+ kobj->parent = parent;
+ return kobject_add_internal(kobj);
}
EXPORT_SYMBOL(kobject_add);

@@ -379,9 +358,12 @@ int kobject_init_and_add(struct kobject *kobj, struct kobj_type *ktype,
kobject_init(kobj, ktype);

va_start(args, fmt);
- retval = kobject_add_varg(kobj, parent, fmt, args);
+ retval = kobject_set_name(kobj, fmt, args);
va_end(args);

+ if (!retval)
+ retval = kobject_add(kobj, parent);
+
return retval;
}
EXPORT_SYMBOL_GPL(kobject_init_and_add);
@@ -653,7 +635,9 @@ struct kobject *kobject_create_and_add(const char *name, struct kobject *parent)
if (!kobj)
return NULL;

- retval = kobject_add(kobj, parent, "%s", name);
+ retval = kobject_set_name(kobj, "%s", name);
+ if (!retval)
+ retval = kobject_add(kobj, parent);
if (retval) {
printk(KERN_WARNING "%s: kobject_add error: %d\n",
__func__, retval);
@@ -798,7 +782,7 @@ static struct kset *kset_create(const char *name,
kset = kzalloc(sizeof(*kset), GFP_KERNEL);
if (!kset)
return NULL;
- retval = kobject_set_name(&kset->kobj, name);
+ retval = kobject_set_name(&kset->kobj, "%s", name);
if (retval) {
kfree(kset);
return NULL;
diff --git a/include/linux/kobject.h b/include/linux/kobject.h
index 58ae8e0..de5f5d1 100644
--- a/include/linux/kobject.h
+++ b/include/linux/kobject.h
@@ -83,8 +83,7 @@ static inline const char *kobject_name(const struct kobject *kobj)

extern void kobject_init(struct kobject *kobj, struct kobj_type *ktype);
extern int __must_check kobject_add(struct kobject *kobj,
- struct kobject *parent,
- const char *fmt, ...);
+ struct kobject *parent);
extern int __must_check kobject_init_and_add(struct kobject *kobj,
struct kobj_type *ktype,
struct kobject *parent,
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index b1cd040..64f7270 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -433,7 +433,11 @@ int blk_register_queue(struct gendisk *disk)
if (ret)
return ret;

- ret = kobject_add(&q->kobj, kobject_get(&dev->kobj), "%s", "queue");
+ ret = kobj_set_name(&q->kobj, "%s", "queue");
+ if (ret < 0)
+ return ret;
+
+ ret = kobject_add(&q->kobj, kobject_get(&dev->kobj));
if (ret < 0)
return ret;

diff --git a/block/elevator.c b/block/elevator.c
index ca86192..f26dca0 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -903,7 +903,9 @@ int elv_register_queue(struct request_queue *q)
struct elevator_queue *e = q->elevator;
int error;

- error = kobject_add(&e->kobj, &q->kobj, "%s", "iosched");
+ error = kobject_set_name(&e->kobj, "%s", "iosched");
+ if (!error)
+ error = kobject_add(&e->kobj, &q->kobj);
if (!error) {
struct elv_fs_entry *attr = e->elevator_type->elevator_attrs;
if (attr) {
diff --git a/drivers/base/core.c b/drivers/base/core.c
index 7ecb193..f0cfa8a 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -625,7 +625,12 @@ static struct kobject *get_device_parent(struct device *dev,
if (!k)
return NULL;
k->kset = &dev->class->p->class_dirs;
- retval = kobject_add(k, parent_kobj, "%s", dev->class->name);
+ retval = kobject_set_name(k, "%s", dev->class->name);
+ if (retval < 0) {
+ kobject_put(k);
+ return NULL;
+ }
+ retval = kobject_add(k, parent_kobj);
if (retval < 0) {
kobject_put(k);
return NULL;
@@ -900,8 +905,7 @@ int device_add(struct device *dev)
set_dev_node(dev, dev_to_node(parent));

/* first, register with generic layer. */
- /* we require the name to be set before, and pass NULL */
- error = kobject_add(&dev->kobj, dev->kobj.parent, NULL);
+ error = kobject_add(&dev->kobj, dev->kobj.parent);
if (error)
goto Error;

diff --git a/drivers/firmware/memmap.c b/drivers/firmware/memmap.c
index d5ea8a6..161a165 100644
--- a/drivers/firmware/memmap.c
+++ b/drivers/firmware/memmap.c
@@ -224,7 +224,8 @@ static int __init memmap_init(void)

list_for_each_entry(entry, &map_entries, list) {
entry->kobj.kset = memmap_kset;
- if (kobject_add(&entry->kobj, NULL, "%d", i++))
+ if (kobject_set_name(&entry->kobj, "%d", i++) ||
+ kobject_add(&entry->kobj, NULL))
kobject_put(&entry->kobj);
}

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 09be637..2f9fa72 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1575,7 +1575,10 @@ static int bind_rdev_to_array(mdk_rdev_t * rdev, mddev_t * mddev)
rdev->mddev = mddev;
printk(KERN_INFO "md: bind<%s>\n", b);

- if ((err = kobject_add(&rdev->kobj, &mddev->kobj, "dev-%s", b)))
+ if ((err = kobject_set_name(&rdev->kobj, "dev-%s", b)))
+ goto fail;
+
+ if ((err = kobject_add(&rdev->kobj, &mddev->kobj)))
goto fail;

ko = &part_to_dev(rdev->bdev->bd_part)->kobj;
diff --git a/drivers/net/iseries_veth.c b/drivers/net/iseries_veth.c
index e44215c..a024c24 100644
--- a/drivers/net/iseries_veth.c
+++ b/drivers/net/iseries_veth.c
@@ -1089,8 +1089,8 @@ static struct net_device *veth_probe_one(int vlan,
return NULL;
}

- kobject_init(&port->kobject, &veth_port_ktype);
- if (0 != kobject_add(&port->kobject, &dev->dev.kobj, "veth_port"))
+ if (kobject_init_and_add(&port->kobject, &veth_port_ktype,
+ &dev->dev.kobj, "%s", "veth_port")
veth_error("Failed adding port for %s to sysfs.\n", dev->name);

veth_info("%s attached to iSeries vlan %d (LPAR map = 0x%.4X)\n",
diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index 03efb06..7c53bb9 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -303,10 +303,10 @@ static int uio_dev_add_attributes(struct uio_device *idev)
map = kzalloc(sizeof(*map), GFP_KERNEL);
if (!map)
goto err_map;
- kobject_init(&map->kobj, &map_attr_type);
map->mem = mem;
mem->map = map;
- ret = kobject_add(&map->kobj, idev->map_dir, "map%d", mi);
+ ret = kobject_init_and_add(&map->kobj, &map_attr_type,
+ idev->map_dir, "map%d", mi);
if (ret)
goto err_map;
ret = kobject_uevent(&map->kobj, KOBJ_ADD);
@@ -328,11 +328,10 @@ static int uio_dev_add_attributes(struct uio_device *idev)
portio = kzalloc(sizeof(*portio), GFP_KERNEL);
if (!portio)
goto err_portio;
- kobject_init(&portio->kobj, &portio_attr_type);
portio->port = port;
port->portio = portio;
- ret = kobject_add(&portio->kobj, idev->portio_dir,
- "port%d", pi);
+ ret = kobject_init_and_add(&portio->kobj, &portio_attr_type,
+ idev->portio_dir, "port%d", pi);
if (ret)
goto err_portio;
ret = kobject_uevent(&portio->kobj, KOBJ_ADD);
--
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