thread died in the pthread_mutex_lock with SIGILL signal - c

Question

I'm developing an project on an embedded linux OS(uclinux, mips CPU), It crashed occasionally.
When I try to check coredump with gdb, I can see that it received a SIGILL signal.
Sometime I can see the backtrace, which showed it died in pthread_mutex_lock. but most time, backtrace is not valid.
A valid backtrace
(gdb) bt
#0 <signal handler called>
#1 0x2ab87fd8 in sigsuspend () from /lib/libc.so.0
#2 0x2aade80c in __pthread_wait_for_restart_signal () from /lib/libpthread.so.0
#3 0x2aadc7ac in __pthread_alt_lock () from /lib/libpthread.so.0
#4 0x2aad81a4 in pthread_mutex_lock () from /lib/libpthread.so.0
#5 0x0042fde8 in aos_mutex_lock (mutex=0x66bea8) at ../../source/ssp/os/sys/linux/aos_lock_linux.c:184
invalid backtrace
(gdb) bt
#0 0x00690430 in ?? ()
#1 0x00690430 in ?? ()
I used pthread_attr_setstackaddr to initial a stack for each thread, so that I can see its call frame through checking its stack. Also, I found it died in pthread_mutex_lock.
I used a wrapper for lock and unlock like
struct aos_mutex_t
{
pthread_mutex_t mutex;
S8 obj_name[AOS_MAX_OBJ_NAME];
S32 lFlag;
};
S32 aos_mutex_lock(AOS_MUTEX_T *mutex)
{
S32 status;
AOS_ASSERT_RETURN(mutex, AOS_EINVAL);
mutex->lFlag++;
status = pthread_mutex_lock( &mutex->mutex );
if (status == 0)
{
return AOS_SUCC;
}
else
{
return AOS_RETURN_OS_ERROR(status);
}
}
/*
* aos_mutex_unlock()
*/
S32 aos_mutex_unlock(AOS_MUTEX_T *mutex)
{
S32 status;
AOS_ASSERT_RETURN(mutex, AOS_EINVAL);
status = pthread_mutex_unlock( &mutex->mutex );
mutex->lFlag--;
if (status == 0)
return AOS_SUCC;
else
{
return AOS_RETURN_OS_ERROR(status);
}
}
All of these mutex is initiated before using them.
I tried gdb to run the program, it didn't die.
I wrote a simple program, 11 threads do nothing bug just lock and unlock in a dead loop. It didn't die.
Is there any suggestion?