AW: AW: AW: [ECOS] Blocking restricted in DSRs

["Neundorf, Alexander" <Alexander dot Neundorf at jenoptik dot com>]

> -----Ursprüngliche Nachricht-----
> Von: ecos-discuss-owner@ecos.sourceware.org
> [mailto:ecos-discuss-owner@ecos.sourceware.org]Im Auftrag von 
> Neundorf,
> Alexander
> Gesendet: Dienstag, 27. Juli 2004 12:44
> An: Nick Garnett; ecos-discuss@sources.redhat.com
> Betreff: AW: AW: AW: [ECOS] Blocking restricted in DSRs
> 
> 
> 
> ...
> > > Ok, and what to do with the variables which are modified and which
> > > should be protected by the mutex ?  E.g. if I have a 
> queue which is
> > > filled by the DSR, and which is checked by the thread which waits
> > > for the signal. Actually I have to ensure that the "take 
> element out
> > > of queue" by the thread is protected against the "put element into
> > > queue" by the DSR.  Do I have to use cyg_scheduler_lock() in the
> > > thread to achieve this ?
> > 
> > Yes. Take a look at the generic serial driver for an 
> example of how to
> > do this.
> 
> Ok, I had a look. The generic serial driver doesn't use 
> cyg_sched_lock() (at least I didn't find it). 

Well, it's not in devs/serial/generic, but in io/serial/current.
So I guess I finally found it:

while (1)                //thread main loop
{
  cyg_drv_dsr_lock();    //does the order of the dsr_lock() and mutex_lock() calls matter ?
  cyg_mutex_lock(mutex);
  while (queue.isEmpty())
    cyg_cond_timed_wait(condition);
  Item *i=queue.pop();       
  cyg_mutex_unlock(mutex);    
  cyg_drv_dsr_unlock();
  //do something with i
  ...
}

Bye
Alex

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