[uClibc 0001013]: pthread_cancel/pthread_join sequence hangs when using select in an other thread

bugs at busybox.net bugs at busybox.net
Fri Nov 17 07:07:56 UTC 2006


A NOTE has been added to this issue. 
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http://busybox.net/bugs/view.php?id=1013 
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Reported By:                jalaber
Assigned To:                uClibc
====================================================================== 
Project:                    uClibc
Issue ID:                   1013
Category:                   Posix Threads
Reproducibility:            always
Severity:                   major
Priority:                   normal
Status:                     assigned
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Date Submitted:             08-31-2006 09:04 PDT
Last Modified:              11-16-2006 23:07 PST
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Summary:                    pthread_cancel/pthread_join sequence hangs when
using select in an other thread
Description: 
Hello,

I have found a very strange bug in uClibc using
pthread_cancel/pthread_join. 

My test program launches 1 thread which basically makes a select call with
a struct timeval set to 600ms. Then the main thread calls pthread_cancel
and pthread_join, followed by a printf. The program hangs. 
However if you remove the printf call, then the program terminates
normally. I have tried to replace the select call with a sem_wait call,
and everything works fine with or without printf. So the problem seems to
happen only with select.

I use buildroot with kernel 2.4.28 and uclibc 0.9.28. I have attached the
program to reproduce. If you try to comment the printf("join OK\n"), it
works for me.

Thank you for your time and help,
Philippe.

====================================================================== 

---------------------------------------------------------------------- 
 dwagner - 10-23-06 11:43  
---------------------------------------------------------------------- 
I think this issue is responsible that the LIRC driver of directfb RC1 does
not terminate. The driver uses select() and
pthread_cancel()/pthread_join().

Please fix that. 

---------------------------------------------------------------------- 
 vapier - 11-16-06 23:07  
---------------------------------------------------------------------- 
here's a tip ... saying things like "Please fix that." makes people think
"Fix it your goddamn self."

the hang may be because of the IO mutex being held by the canceled thread
... if you turn on PDEBUG in libpthread/linuxthreads/debug.h, that may
give you helpful output 

Issue History 
Date Modified   Username       Field                    Change               
====================================================================== 
08-31-06 09:04  jalaber        New Issue                                    
08-31-06 09:04  jalaber        Status                   new => assigned     
08-31-06 09:04  jalaber        Assigned To               => uClibc          
08-31-06 09:04  jalaber        File Added: pthread_join_test.c                  
 
10-23-06 11:41  dwagner        Issue Monitored: dwagner                     
10-23-06 11:43  dwagner        Note Added: 0001715                          
11-16-06 23:07  vapier         Note Added: 0001744                          
======================================================================




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