RE: Do PTHREAD_PROCESS_SHARED mutexes/condvars w ork?

This change is already in the impending ngpt-2.2.0 that will be released
very soon.

 

Dave Howell

 

-----Original Message-----
From: Chris McFarlen [mailto:[email protected]] 
Sent: Friday, December 27, 2002 4:14 PM
To: '[email protected]'
Subject: RE: [pthreads-devel] Do PTHREAD_PROCESS_SHARED mutexes/condvars
w ork?

 

Well, I get to respond to my own question, but you guys can tell me if
this is right.  This patch fixes the problem:

 

diff -Eu -x '*\.o' ngpt-2.0.4/pth_sync.c ngpt-2.0.4-my/pth_sync.c
--- ngpt-2.0.4/pth_sync.c 2002-11-19 12:03:54.000000000 -0600
+++ ngpt-2.0.4-my/pth_sync.c 2002-12-27 14:55:36.000000000 -0600
@@ -408,7 +408,9 @@
 
 wait:
     /* already locked by caller? */
-    if (mutex->mx_owner == current && mutex->mx_count >= 1) {
+    if (mutex->mx_owner == current && 
+        mutex->mx_owner_pid == descr->pid &&
+        mutex->mx_count >= 1) {
  if (mutex->mx_type == PTH_MUTEX_RECURSIVE_NP) {
      /* recursive lock */
             mutex->mx_count++;

Chris McFarlen

T-NETIX, Inc.

	-----Original Message-----
	From: Chris McFarlen 
	Sent: Friday, December 27, 2002 2:58 PM
	To: '[email protected]'
	Subject: [pthreads-devel] Do PTHREAD_PROCESS_SHARED
mutexes/condvars work?

	I need to do some process syncronization, but the
PTHREAD_PROCESS_SHARED attribute does not seem to work. I am using NGPT
2.0.4, and I have tried a stock 2.4.19 with the futex patch, and a
2.5.43 development kernel.  Both kernel versions have the same results.
I have some test code that yields the error, and I have made one
modification to test_str03.c that also shows the error.  

	The error comes from pthread_mutex_lock() when the mutex is
locked by another process (the mutex data is shared via shared memory,
and initialized with an attribute that has PTHREAD_PROCESS_SHARED set).
The error is EDEADLK.

	I can post the test code I have and the change to get test_str03
to fail, if there is interest in helping out.  But I wanted to make sure
that NGPT tries to support PTHREAD_PROCESS_SHARED before I posted all of
that.  The documentation seems to say that NGPT does and does not
support PTHREAD_PROCESS_SHARED in different places(there is a test for
the case, test_str03, but you have to supply a -s parameter, and then
that really doesn't work anyway...).

	Thanks, 
	Chris McFarlen 
	T-NETIX, Inc.