There are 3 choices.
1. I'm going to put pthread_mutex out in a few days.
2. On a uniprocessor you should use Jery Epplin's semaphore package right
now.
3. Or you can do things the correct way and define synchronization for
your specific tasks using suspend and test_and_set.
For example, suppose thread X and Y share buffer B and want to
have exclusive use of it for non-smp
pthread_t waiter, buffer_user;
access_lock(){
unsigned int s;
rtl_no_interrupts(s)
if(buffer_user && (buffer_user != pthread_self()){
waiter = pthread_self();
pthread_suspend_np(waiter);
}
buffer_user = pthread_self();
rtl_restore_interrupts(s);
}
free_lock()
unsigned int s;
rtl_no_interrupts(s);
buffer_user = 0;
if(waiter && (waiter != pthread_self()))pthread_wakeup(waiter);
rtl_restore_interrupts(s);
return;
}
Should work. If you want SMP you need to do some spinlocks too.
I'm working on making this easier, but it is not so hard.
waiting[
spinlock_t lock;
access_buffer(){
unsigned int pstate;
rtl_spin_lock_irqsave(&lock,state);
while(1){
if(in_use){
waiter = pthread_self();
rtl_spin_unlock_irqrestore(buffersynclock,state);
rtl_suspend(waiter);
}
in_use = 1;
if(test_and_set_bit(0,&otherowns))
pthread_suspend_np(pthread_self())
Get_other_to_wait:
test_and_set
On Thu, Jan 20, 2000 at 11:15:08PM -0200, Anderson Borges wrote:
> HELP !!!!
>
> I need to know if there is any way to use semaphores to block REAL-TIME tasks in
>RT-Linux.(not RTAI)
> I need to communicate two REAL-TIME tasks with blockade !!!!
> How can I do it using RT-Linux ?!?!?
>
> Thanks !!!
--
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