Hi Greg,
While playing with hotplug memory remove on 2.6.24-mm1, I
noticed that /sysfs directory entries are not getting removed.
sysdev_unregister() used to call kobject_unregister().
But in 2.6.24-mm1, its only dropping the ref. It should
call kobject_del() to remove the object. Correct ?
With this change, the directories are getting removed
correctly. Comments ?
Thanks,
Badari
sysdev_unregister() should call kobject_del() to remove
the object.
Signed-off-by: Badari Pulavarty <[email protected]>
---
drivers/base/sys.c | 1 +
1 file changed, 1 insertion(+)
Index: linux-2.6.24/drivers/base/sys.c
===================================================================
--- linux-2.6.24.orig/drivers/base/sys.c 2008-02-05 09:56:56.000000000 -0800
+++ linux-2.6.24/drivers/base/sys.c 2008-02-07 15:38:17.000000000 -0800
@@ -265,6 +265,7 @@ void sysdev_unregister(struct sys_device
}
mutex_unlock(&sysdev_drivers_lock);
+ kobject_del(&sysdev->kobj);
kobject_put(&sysdev->kobj);
}
On Thu, Feb 07, 2008 at 03:56:58PM -0800, Badari Pulavarty wrote:
> Hi Greg,
>
> While playing with hotplug memory remove on 2.6.24-mm1, I
> noticed that /sysfs directory entries are not getting removed.
>
> sysdev_unregister() used to call kobject_unregister().
> But in 2.6.24-mm1, its only dropping the ref. It should
> call kobject_del() to remove the object. Correct ?
>
> With this change, the directories are getting removed
> correctly. Comments ?
Ick, no, this shouldn't be needed, someone else must be holding a
reference to the kobject device somewhere. See the kobject documenation
for more info.
I'll try to see where we grab 2 references...
Have I mentioned lately that I hate the sysdev code?
ugh,
greg k-h
On Thu, 2008-02-07 at 16:38 -0800, Greg KH wrote:
> On Thu, Feb 07, 2008 at 03:56:58PM -0800, Badari Pulavarty wrote:
> > Hi Greg,
> >
> > While playing with hotplug memory remove on 2.6.24-mm1, I
> > noticed that /sysfs directory entries are not getting removed.
> >
> > sysdev_unregister() used to call kobject_unregister().
> > But in 2.6.24-mm1, its only dropping the ref. It should
> > call kobject_del() to remove the object. Correct ?
> >
> > With this change, the directories are getting removed
> > correctly. Comments ?
>
> Ick, no, this shouldn't be needed, someone else must be holding a
> reference to the kobject device somewhere. See the kobject documenation
> for more info.
>
> I'll try to see where we grab 2 references...
I will take a closer look then. I was taking easy way out :(
Thanks,
Badari
On Thu, Feb 07, 2008 at 05:25:46PM -0800, Badari Pulavarty wrote:
> On Thu, 2008-02-07 at 16:38 -0800, Greg KH wrote:
> > On Thu, Feb 07, 2008 at 03:56:58PM -0800, Badari Pulavarty wrote:
> > > Hi Greg,
> > >
> > > While playing with hotplug memory remove on 2.6.24-mm1, I
> > > noticed that /sysfs directory entries are not getting removed.
> > >
> > > sysdev_unregister() used to call kobject_unregister().
> > > But in 2.6.24-mm1, its only dropping the ref. It should
> > > call kobject_del() to remove the object. Correct ?
> > >
> > > With this change, the directories are getting removed
> > > correctly. Comments ?
> >
> > Ick, no, this shouldn't be needed, someone else must be holding a
> > reference to the kobject device somewhere. See the kobject documenation
> > for more info.
> >
> > I'll try to see where we grab 2 references...
>
> I will take a closer look then. I was taking easy way out :(
Hm, I don't see anything obvious in the sys.c core. What code is
controlling these objects that you are creating and removing from the
system?
thanks,
greg k-h
On Thu, 2008-02-07 at 20:55 -0800, Greg KH wrote:
> On Thu, Feb 07, 2008 at 05:25:46PM -0800, Badari Pulavarty wrote:
> > On Thu, 2008-02-07 at 16:38 -0800, Greg KH wrote:
> > > On Thu, Feb 07, 2008 at 03:56:58PM -0800, Badari Pulavarty wrote:
> > > > Hi Greg,
> > > >
> > > > While playing with hotplug memory remove on 2.6.24-mm1, I
> > > > noticed that /sysfs directory entries are not getting removed.
> > > >
> > > > sysdev_unregister() used to call kobject_unregister().
> > > > But in 2.6.24-mm1, its only dropping the ref. It should
> > > > call kobject_del() to remove the object. Correct ?
> > > >
> > > > With this change, the directories are getting removed
> > > > correctly. Comments ?
> > >
> > > Ick, no, this shouldn't be needed, someone else must be holding a
> > > reference to the kobject device somewhere. See the kobject documenation
> > > for more info.
> > >
> > > I'll try to see where we grab 2 references...
> >
> > I will take a closer look then. I was taking easy way out :(
>
> Hm, I don't see anything obvious in the sys.c core. What code is
> controlling these objects that you are creating and removing from the
> system?
add_memory_block()/register_memory() is creating sysfs entries
for the memory blocks.
I am trying to make use of remove_memory_block() to clean up
sysfs entries. BTW, remove_memory_block() is never tested
before, since we don't support memory remove yet.
Thanks,
Badari
On Thu, Feb 07, 2008 at 09:08:42PM -0800, Badari Pulavarty wrote:
>
> On Thu, 2008-02-07 at 20:55 -0800, Greg KH wrote:
> > On Thu, Feb 07, 2008 at 05:25:46PM -0800, Badari Pulavarty wrote:
> > > On Thu, 2008-02-07 at 16:38 -0800, Greg KH wrote:
> > > > On Thu, Feb 07, 2008 at 03:56:58PM -0800, Badari Pulavarty wrote:
> > > > > Hi Greg,
> > > > >
> > > > > While playing with hotplug memory remove on 2.6.24-mm1, I
> > > > > noticed that /sysfs directory entries are not getting removed.
> > > > >
> > > > > sysdev_unregister() used to call kobject_unregister().
> > > > > But in 2.6.24-mm1, its only dropping the ref. It should
> > > > > call kobject_del() to remove the object. Correct ?
> > > > >
> > > > > With this change, the directories are getting removed
> > > > > correctly. Comments ?
> > > >
> > > > Ick, no, this shouldn't be needed, someone else must be holding a
> > > > reference to the kobject device somewhere. See the kobject documenation
> > > > for more info.
> > > >
> > > > I'll try to see where we grab 2 references...
> > >
> > > I will take a closer look then. I was taking easy way out :(
> >
> > Hm, I don't see anything obvious in the sys.c core. What code is
> > controlling these objects that you are creating and removing from the
> > system?
>
> add_memory_block()/register_memory() is creating sysfs entries
> for the memory blocks.
>
> I am trying to make use of remove_memory_block() to clean up
> sysfs entries. BTW, remove_memory_block() is never tested
> before, since we don't support memory remove yet.
So how are you testing the sysdev removal logic then if you can't remove
memory?
Oh, one thing, remove the link in unregister_memory, before you call
sysdev_unregister(). You are trying to get the name of a kobject, and
the whole object, that has just been blown away, not nice...
Which makes me believe your statement about this never being tested
before :)
thanks,
greg k-h
On Thu, 2008-02-07 at 21:41 -0800, Greg KH wrote:
> On Thu, Feb 07, 2008 at 09:08:42PM -0800, Badari Pulavarty wrote:
> >
> > On Thu, 2008-02-07 at 20:55 -0800, Greg KH wrote:
> > > On Thu, Feb 07, 2008 at 05:25:46PM -0800, Badari Pulavarty wrote:
> > > > On Thu, 2008-02-07 at 16:38 -0800, Greg KH wrote:
> > > > > On Thu, Feb 07, 2008 at 03:56:58PM -0800, Badari Pulavarty wrote:
> > > > > > Hi Greg,
> > > > > >
> > > > > > While playing with hotplug memory remove on 2.6.24-mm1, I
> > > > > > noticed that /sysfs directory entries are not getting removed.
> > > > > >
> > > > > > sysdev_unregister() used to call kobject_unregister().
> > > > > > But in 2.6.24-mm1, its only dropping the ref. It should
> > > > > > call kobject_del() to remove the object. Correct ?
> > > > > >
> > > > > > With this change, the directories are getting removed
> > > > > > correctly. Comments ?
> > > > >
> > > > > Ick, no, this shouldn't be needed, someone else must be holding a
> > > > > reference to the kobject device somewhere. See the kobject documenation
> > > > > for more info.
> > > > >
> > > > > I'll try to see where we grab 2 references...
> > > >
> > > > I will take a closer look then. I was taking easy way out :(
> > >
> > > Hm, I don't see anything obvious in the sys.c core. What code is
> > > controlling these objects that you are creating and removing from the
> > > system?
> >
> > add_memory_block()/register_memory() is creating sysfs entries
> > for the memory blocks.
> >
> > I am trying to make use of remove_memory_block() to clean up
> > sysfs entries. BTW, remove_memory_block() is never tested
> > before, since we don't support memory remove yet.
>
> So how are you testing the sysdev removal logic then if you can't remove
> memory?
I am now adding code to remove memory, I am making use of the
existing unregister_memory() code and ran into this.
>
> Oh, one thing, remove the link in unregister_memory, before you call
> sysdev_unregister(). You are trying to get the name of a kobject, and
> the whole object, that has just been blown away, not nice...
I can add remove link before unregister() as you suggested.
Regarding accessing kobject after freeing up, no one calls with "root".
Why not clean it up first, like this ?
Dave, are you okay with this ?
Thanks,
Badari
register_memory()/unregister_memory() never gets called with
"root". unregister_memory() is accessing kobject_name of
the object just freed up. Since no one uses the code,
lets take the code out. And also, make register_memory()
static (since unregister_memory() is already static).
Signed-off-by: Badari Pulavarty <[email protected]>
---
drivers/base/memory.c | 20 +++++---------------
1 file changed, 5 insertions(+), 15 deletions(-)
Index: linux-2.6.24/drivers/base/memory.c
===================================================================
--- linux-2.6.24.orig/drivers/base/memory.c 2008-02-07 16:59:52.000000000 -0800
+++ linux-2.6.24/drivers/base/memory.c 2008-02-08 08:26:33.000000000 -0800
@@ -62,8 +62,8 @@ void unregister_memory_notifier(struct n
/*
* register_memory - Setup a sysfs device for a memory block
*/
-int register_memory(struct memory_block *memory, struct mem_section *section,
- struct node *root)
+static
+int register_memory(struct memory_block *memory, struct mem_section *section)
{
int error;
@@ -71,26 +71,16 @@ int register_memory(struct memory_block
memory->sysdev.id = __section_nr(section);
error = sysdev_register(&memory->sysdev);
-
- if (root && !error)
- error = sysfs_create_link(&root->sysdev.kobj,
- &memory->sysdev.kobj,
- kobject_name(&memory->sysdev.kobj));
-
return error;
}
static void
-unregister_memory(struct memory_block *memory, struct mem_section *section,
- struct node *root)
+unregister_memory(struct memory_block *memory, struct mem_section *section)
{
BUG_ON(memory->sysdev.cls != &memory_sysdev_class);
BUG_ON(memory->sysdev.id != __section_nr(section));
sysdev_unregister(&memory->sysdev);
- if (root)
- sysfs_remove_link(&root->sysdev.kobj,
- kobject_name(&memory->sysdev.kobj));
}
/*
@@ -361,7 +351,7 @@ static int add_memory_block(unsigned lon
mutex_init(&mem->state_mutex);
mem->phys_device = phys_device;
- ret = register_memory(mem, section, NULL);
+ ret = register_memory(mem, section);
if (!ret)
ret = mem_create_simple_file(mem, phys_index);
if (!ret)
@@ -415,7 +405,7 @@ int remove_memory_block(unsigned long no
mem_remove_simple_file(mem, state);
mem_remove_simple_file(mem, phys_device);
mem_remove_simple_file(mem, removable);
- unregister_memory(mem, section, NULL);
+ unregister_memory(mem, section);
return 0;
}
On Fri, 2008-02-08 at 08:42 -0800, Badari Pulavarty wrote:
>
> I can add remove link before unregister() as you suggested.
>
> Regarding accessing kobject after freeing up, no one calls with
> "root".
> Why not clean it up first, like this ?
>
> Dave, are you okay with this ?
Yeah, I don't see any users of it, either. It looks fine to me.
-- Dave
On Thu, 2008-02-07 at 20:55 -0800, Greg KH wrote:
> On Thu, Feb 07, 2008 at 05:25:46PM -0800, Badari Pulavarty wrote:
> > On Thu, 2008-02-07 at 16:38 -0800, Greg KH wrote:
> > > On Thu, Feb 07, 2008 at 03:56:58PM -0800, Badari Pulavarty wrote:
> > > > Hi Greg,
> > > >
> > > > While playing with hotplug memory remove on 2.6.24-mm1, I
> > > > noticed that /sysfs directory entries are not getting removed.
> > > >
> > > > sysdev_unregister() used to call kobject_unregister().
> > > > But in 2.6.24-mm1, its only dropping the ref. It should
> > > > call kobject_del() to remove the object. Correct ?
> > > >
> > > > With this change, the directories are getting removed
> > > > correctly. Comments ?
> > >
> > > Ick, no, this shouldn't be needed, someone else must be holding a
> > > reference to the kobject device somewhere. See the kobject documenation
> > > for more info.
> > >
> > > I'll try to see where we grab 2 references...
> >
> > I will take a closer look then. I was taking easy way out :(
>
> Hm, I don't see anything obvious in the sys.c core. What code is
> controlling these objects that you are creating and removing from the
> system?
>
I found the culprit. Its not in sys.c core :)
remove_memory_block() takes a reference on kobject by calling
find_memory_block(). It then calls unregister_memory() to free up sysfs
entry.
It drops only one ref (which it got at register time). So it never gets
freed up. I am going to send out a separate patch for it.
Thanks for your help.
Thanks,
Badari
On Fri, Feb 08, 2008 at 03:22:29PM -0800, Badari Pulavarty wrote:
>
> On Thu, 2008-02-07 at 20:55 -0800, Greg KH wrote:
> > On Thu, Feb 07, 2008 at 05:25:46PM -0800, Badari Pulavarty wrote:
> > > On Thu, 2008-02-07 at 16:38 -0800, Greg KH wrote:
> > > > On Thu, Feb 07, 2008 at 03:56:58PM -0800, Badari Pulavarty wrote:
> > > > > Hi Greg,
> > > > >
> > > > > While playing with hotplug memory remove on 2.6.24-mm1, I
> > > > > noticed that /sysfs directory entries are not getting removed.
> > > > >
> > > > > sysdev_unregister() used to call kobject_unregister().
> > > > > But in 2.6.24-mm1, its only dropping the ref. It should
> > > > > call kobject_del() to remove the object. Correct ?
> > > > >
> > > > > With this change, the directories are getting removed
> > > > > correctly. Comments ?
> > > >
> > > > Ick, no, this shouldn't be needed, someone else must be holding a
> > > > reference to the kobject device somewhere. See the kobject documenation
> > > > for more info.
> > > >
> > > > I'll try to see where we grab 2 references...
> > >
> > > I will take a closer look then. I was taking easy way out :(
> >
> > Hm, I don't see anything obvious in the sys.c core. What code is
> > controlling these objects that you are creating and removing from the
> > system?
> >
>
> I found the culprit. Its not in sys.c core :)
Glad to hear it :)
> remove_memory_block() takes a reference on kobject by calling
> find_memory_block(). It then calls unregister_memory() to free up sysfs
> entry.
> It drops only one ref (which it got at register time). So it never gets
> freed up. I am going to send out a separate patch for it.
Ah, nice catch.
thanks,
greg k-h