Re: process shared mutex/cond var

Hello!

On Mon, Aug 19, 2002 at 08:22:27AM +0200, Hahn, Karsten wrote:
> On Friday 16 August 2002 08:50, Pavan Sikka wrote:
> > The producer freezes as soon as the consumer starts. The consumer goes
> > into an endless loop around the pthread_cond_wait since it returns
> > immediately with no error !
> I had the same problem (linux 2.4.19 with futex patch) and solved it (after 
> spending two days with debugging) by upgrading to linux 2.5.31.
> I'm not sure if this is a bug in ngpt or linux, maybe someone with a little 
> more kernel insight can look into it?
Apply the attached patch file. The problem was already in NGPT 2.0.0 and I was
sure the patch was included in 2.0.1 but this is unfortunately not the case.

Bye, Uwe

-- 
Dr. Uwe Girlich              email: [email protected]
Philosys Software GmbH       www: www.philosys.de
Edisonstrasse 6              phone: +49 89 321407-44
D-85716 Unterschleissheim    fax: +49 89 321407-12

--- linux-2.4.19-rc1-ngpt-2.0.0/kernel/futex.c.orig	Wed Jul 10 16:07:09 2002
+++ linux-2.4.19-rc1-ngpt-2.0.0/kernel/futex.c	Wed Jul 10 16:07:34 2002
@@ -238,7 +238,7 @@
 
 	poll_wait(filp, &q->waiters, wait);
 	spin_lock(&futex_lock);
-	if (!list_empty(&q->list))
+	if (list_empty(&q->list))
 		ret = POLLIN | POLLRDNORM;
 	spin_unlock(&futex_lock);