Hi,
I'm coding a driver (can be found from
http://hardsid.sourceforge.net/ is someone is actually interested)
that uses a kernel thread to do the actual work asynchronously from
rest of the world. The thread is created when opening a character
device and exits when the device is closed.
This works fine otherwise but if the user mode process opens and
closes the device multiple times during its lifetime I get N-1
zombie kernel threads where N is the number of opens.
The code goes like this:
in device open:
DECLARE_MUTEX_LOCKED(sem);
int rmmod = 0;
rmmod = 0;
notify = &sem;
kernel_thread(hsid_thread, (void *)sid_data, 0);
down(&sem);
notify = NULL;
in device close:
notify = &sem;
rmmod = 1;
up(&todoSem); // just to wake the thread to do something
down(&sem);
notify = NULL;
rmmod = 0;
and the thread itself does:
[daemonize() etc.]
/* Notify the parent */
if(notify != NULL)
up(notify);
for(;;)
{
if (rmmod || signal_pending(current))
break;
/* We sit here waiting for something to do */
down_interruptible(&todoSem);
if (rmmod || signal_pending(current))
break;
[actual work]
}
if(notify != NULL)
up(notify);
return 0;
I think this worked fine in earlier 2.4 versions (not sure though),
but I'm now seeing this in both 2.4.18-pre7 and 2.5.2-dj6, UP and SMP.
Thanks,
// Jarno
On 30 Jan 2002 06:06:50 +0200
Jarno Paananen <[email protected]> wrote:
> Hi,
Good time of day.
> that uses a kernel thread to do the actual work asynchronously from
> rest of the world. The thread is created when opening a character
> device and exits when the device is closed.
Maybe you should use do_exit() at the end or complete_and_exit()?
> [daemonize() etc.]
...
do_exit(0); // At least usb hub do it in such manner.
> return 0;
> Thanks,
I hope this will help you.
> // Jarno
> -
Evgeniy Polyakov ( s0mbre ).
On Wed, Jan 30, 2002 at 06:06:50AM +0200, Jarno Paananen wrote:
> http://hardsid.sourceforge.net/ is someone is actually interested)
> that uses a kernel thread to do the actual work asynchronously from
> rest of the world. The thread is created when opening a character
> device and exits when the device is closed.
read frey's guide and look at some real code to see how to do this.
Think you are missing a reparent_to_init(). I don't know if bleeding
2.5 includes this in daemonize() yet.
You should really have asked this on kernelnewbies mailing list btw
http://www.kernelnewbies.org/
regards
john
--
"In no sense is [in]stability a reason to move to a new version. It's never a
reason."
- Bill Gates