Hi all,
I reopen the subject with a potential new bug submission. I've seen that this
topic has been treated here a couple of time already, and that there is a fix
that may be related to that specific prb (see commit r21980 | vapier |
2008-05-15 04:03:13 +0200 (Thu, 15 May 2008) | 9 lines)
The prb is that I get a segfault when I try to use pthread_create from a
dynamically linked library. The difference with the above fix use case is that
I "manually" link the library using dlopen. I initially found this prb while
trying to use the Lua (www.lua.org) VM with uclibc. Lua supports loading
extension as so files so it uses dlopen.
I reduced and reproduced the prb with this simple use case:
2 files (attached): test.c and lib.c
test.c contains the main() that will load the so file compiled from lib.c.
lib.c actually creates a thread. (well crashed when trying to create a
thread).
I used uClibc-0.9.30.1
To compile the file I did:
i686-linux-gcc -o test test.c -ldl
i686-linux-gcc -fPIC -shared -o libtest.so lib.c -lpthread
then to test it:
export LD_LIBRARY_PATH=.
./test libtest.so
Gdb gives me this:
[Thread debugging using libthread_db enabled]
[New Thread 0x400 (LWP 32200)]
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x400 (LWP 32200)]
0xf7f23621 in __pthread_initialize_manager () at
libpthread/linuxthreads.old/pthread.c:515
515 *__libc_multiple_threads_ptr = 1;
(gdb) l
510 int manager_pipe[2];
511 int pid;
512 int report_events;
513 struct pthread_request request;
514
515 *__libc_multiple_threads_ptr = 1;
516
517 /* If basic initialization not done yet (e.g. we're called from a
518 constructor run before our constructor), do it now */
519 if (__pthread_initial_thread_bos == NULL) pthread_initialize();
(gdb) display __libc_multiple_threads_ptr
1: __libc_multiple_threads_ptr = (int *) 0x0
So __libc_multiple_threads_ptr is null so it seg fault !
Going further would require specific knowledge of the implementation.
Any one has an idea ?
PS: I reproduced it on i686 architecture, but I initially found the bug on arm
target.
C.
#include <netdb.h>
#include <stdio.h>
#include <stdint.h>
#include <dlfcn.h>
typedef int (*func)(void);
int main(int argn, char* argv[])
{
if(argn<2 || !argv[1])
{
printf("give a so name!\n", argv[1]);
return -1;
}
void *lib = dlopen(argv[1], RTLD_NOW);
if(!lib)
{
printf("file %s not found\n", argv[1]);
return -1;
}
func f = dlsym(lib, "runthething");
if(!f)
{
printf("function runthething not found\n", argv[1]);
return -1;
}
f();
printf("Bye !\n");
return 0;
}#include <pthread.h>
#include <stdio.h>
void* exec(void* t)
{
printf("Thread\n");
return 0;
}
int runthething()
{
pthread_t execThread;
pthread_create(&execThread, 0, exec, 0);
printf("debug1.1\n");
pthread_detach(execThread);
printf("debug2\n");
sleep(5);
return 1;
}
_______________________________________________
uClibc mailing list
uClibc@uclibc.org
http://lists.busybox.net/mailman/listinfo/uclibc
