On Thu, Nov 04, 2004 at 12:52:38PM -0800, Greg KH wrote:
> Hi,
>
> I get the following BUG in the sysfs code when I do:
> 	- plug in a usb-serial device.
> 	- open the port with 'cat /dev/ttyUSB0'
> 	- unplug the device.
> 	- stop the 'cat' process with control-C
>
> This used to work just fine before your big sysfs changes.

There is a similar problem reported by s390 people where we see parent
kobject (directory) going away before child kobject (sub-directory). It
seems kobject code is able to handle this, but not the sysfs. What could
be happening that in sysfs_remove_dir() of parent directory, we try to
remove its contents. It works well with the regular files as it is the
final removal for sysfs_dirent corresponding to the files. But in case
of sub-directory we are doing an extra sysfs_put().  Once while removing
parent and the other one being the one from when sysfs_remove_dir() is
called for the child.

The following patch worked for the s390 people, I hope same will work in
this case also.


o Do not remove sysfs_dirents corresponding to the sub-directory in
  sysfs_remove_dir(). They will be removed in the sysfs_remove_dir() call
  for the specific sub-directory.
Signed-off-by: Maneesh Soni <maneesh@in.ibm.com>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>