Hi,
I've made up a small test program for my issue with pthread_cond_wait and gdb.
Sorry for posting code again, I've made it as compact as possible.
The behaviour of the attached program depends on whether it is run via
gdbserver or without.
When run via gdbserver, the pthread_cond_wait sometimes returns EPERM:
Remote debugging from host 10.0.10.10
T0: pthread_cond_wait: 1
... repeats for T0 and T1 ...
T1: pthread_cond_wait: 1
T1: pthread_cond_wait: 1
T0: pthread_cond_wait: 1
T2: pthread_cond_wait: 0
Child exited with retcode = 0
Started directly, it prints what I would expect:
T0: pthread_cond_wait: 0
T1: pthread_cond_wait: 0
T2: pthread_cond_wait: 0
Am I missing something when configuring the threads, cond variable etc.?
About my environment:
- Xenomai 2.5.5.2, unmodified
- blackfin FDPIC toolchain 2010R1-RC4 (gcc 4.3.5, gdb 6.6, gdbserver 6.5)
- blackfin-linux-dist 2010R1-RC5 (kernel 2.6.34 with I-pipe upgraded to
1.15-01)
I compile "try.c" with the following command line:
bfin-linux-uclibc-gcc \
-I/opt/uClinux/blackfin-linux-dist/staging/usr/include \
-L/opt/uClinux/blackfin-linux-dist/staging/usr/lib \
-Wl,@/opt/uClinux/blackfin-linux-dist/staging/usr/lib/posix.wrappers \
-g -fPIC -fmessage-length=0 -mfast-fp -D_GNU_SOURCE -D_REENTRANT -D__XENO__ \
-o try try.c -lxenomai -lpthread_rt
The gdb script contains only a few commands:
set verbose on
set solib-absolute-prefix notexistent
set solib-search-path
/opt/uClinux/blackfin-linux-dist/staging/usr/lib:/opt/uClinux/bfin-linux-uclibc/bfin-linux-uclibc/runtime/lib
file try
target remote 10.0.10.9:2222
break main
cont
cont
The pthread_cond_wait, returning EPERM immediately, causes a lockup in a
program that I'm trying to debug (see old thread about gdb/gdbserver hanging).
I currently know no measure against this behaviour other than to sleep for a
while in that case...
Thanks for any hints!
Kolja
/* 2010-12-27 - test program for pthread_cond_wait */
#include <stdio.h>
#include <string.h>
#include <pthread.h>
#define PRIORITY 1
#define NUM_THREADS 3
volatile int run;
pthread_cond_t cond;
pthread_mutex_t mutex;
void* test_thread(void *cookie)
{
int tnum = *(int*)cookie;
pthread_mutex_lock(&mutex);
while (run)
{
int r = pthread_cond_wait(&cond, &mutex);
printf("T%d: pthread_cond_wait: %d\n", tnum, r);
}
pthread_mutex_unlock(&mutex);
return NULL;
}
int main (void)
{
int i, r;
int tnum[NUM_THREADS];
pthread_t tid[NUM_THREADS];
run = 1;
r = pthread_cond_init(&cond, NULL); if (r!=0) printf("cond_init: %d\n", r);
r = pthread_mutex_init(&mutex, NULL); if (r!=0) printf("mutex_init: %d\n", r);
for (i=0; i<NUM_THREADS; i++)
{
tnum[i] = i;
r = pthread_create(&(tid[i]), NULL, test_thread, &(tnum[i]));
if (r!=0) printf("create(%d): %d\n", i, r);
}
sleep(1);
run = 0;
r = pthread_cond_broadcast(&cond); if (r!=0) printf("cond_broadcast: %d\n", r);
for (i=0; i<NUM_THREADS; i++)
{
void *rp;
r = pthread_join(tid[i], &rp);
if (r!=0) printf("join(%d): %d\n", i, r);
}
return r;
}
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