Re: mpc / linux kernel - user space

[Juergen Oberhofer <e9826367@student.tuwien.ac.at>]

Hello,
I tried to make use of wake_up_interruptible(wq) in my module as
following (I just wanted to test if I'm using it correctly):
If I'm doing insmod, the module blocks in the wake_up_interruptible call.
Does somebody know why? Maybe because there is no process sleeping? How do
I check this?

DECLARE_WAIT_QUEUE_HEAD(wq);

int sleepy_init(void) {
  test_file = create_proc_entry("test", 0666, NULL);
  if(test_file == NULL) {
    return -ENOMEM;
  }

  wake_up_interruptible(&wq);

  return 0;
}

void sleepy_cleanup(void) {
remove_proc_entry("test", NULL);
}

module_init(test_init);
module_exit(test_cleanup);


Best regards,
Juergen

On Fri, 2003-11-28 at 10:21, Aain_Devarenne%ZODIAC@zodiac.com wrote:
> Hi everybody
>
> I 'm pending on the same problem as Juergen,
> - How can a User Space Thread Wait for a signaling event set by KERNEL ?

e.g. issue a read on some device driver (/dev/<your driver>
which will block until an interrupt has occured.
something like this:

DECLARE_WAIT_QUEUE_HEAD(mydriver_queue);

ssize_t mydriver_read(
struct file *filp,
char *buf,
size_t count,
loff_t *f_pos)
{
/* wait on interrupt */
while (1) {
interruptible_sleep_on(&mydriver_queue);
if (signal_pending (current)) /* a signal arrived */
return -ERESTARTSYS; /* tell the fs layer to handle it */
else break;
}
return 0;
}

void mydriver_irqhandler(unsigned long arg)
{
wake_up_interruptible(&mydriver_queue);
}

Jaap-Jan


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