On 04/23/2015 02:55 AM, Eunbong Song wrote:
> current_obj is declared as a thread-local storage.
> This prevent to detect locking problem between multiple threads because
> each thread has it's own current_obj. liblockdep can only detect locking
> problem in a single
> thread. However, pthread_mutex_xxx, pthread_rwlock_xxx functions are mainly
> used for synchro
> nization of data between multiple threads.
> This patch changes current_obj to non thread-local storage. and
> current_obj.pid is getting
> from getpid system call.
um... It always worked with threads:
$ cat tests/ABBA_threads.c
#include <liblockdep/mutex.h>
#include "common.h"
pthread_mutex_t a, b;
void *thread_a(void *arg)
{
LOCK_UNLOCK_2(a, b);
return NULL;
}
void *thread_b(void *arg)
{
LOCK_UNLOCK_2(b, a);
return NULL;
}
void main(void)
{
pthread_t ta, tb;
pthread_mutex_init(&a, NULL);
pthread_mutex_init(&b, NULL);
pthread_create(&ta, NULL, thread_a, NULL);
pthread_create(&tb, NULL, thread_b, NULL);
pthread_join(ta, NULL);
pthread_join(tb, NULL);
}
$ tests/ABBA_threads
======================================================
[ INFO: possible circular locking dependency detected ]
liblockdep 4.0.0
-------------------------------------------------------
ABBA_threads/12101 is trying to acquire lock:
(0x10bb700){......}, at: tests/ABBA_threads() [0x401333]
but task is already holding lock:
(0x10bb680){......}, at: tests/ABBA_threads() [0x401333]
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (0x10bb680){......}:
tests/ABBA_threads[0x4019d3]
tests/ABBA_threads[0x4036f6]
tests/ABBA_threads[0x4039c2]
tests/ABBA_threads[0x403fde]
tests/ABBA_threads[0x404aa7]
tests/ABBA_threads[0x405250]
tests/ABBA_threads[0x4053d3]
tests/ABBA_threads[0x4055cd]
tests/ABBA_threads[0x40135d]
tests/ABBA_threads[0x401395]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x80a5)[0x7f8e6e1dc0a5]
/lib/x86_64-linux-gnu/libc.so.6(clone+0x6d)[0x7f8e6df09cfd]
-> #0 (0x10bb700){......}:
tests/ABBA_threads[0x4019d3]
tests/ABBA_threads[0x402f51]
tests/ABBA_threads[0x4035c4]
tests/ABBA_threads[0x4039c2]
tests/ABBA_threads[0x403fde]
tests/ABBA_threads[0x404aa7]
tests/ABBA_threads[0x405565]
tests/ABBA_threads(pthread_mutex_lock+0x51)[0x4063fd]
tests/ABBA_threads[0x401333]
tests/ABBA_threads[0x4013c6]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x80a5)[0x7f8e6e1dc0a5]
/lib/x86_64-linux-gnu/libc.so.6(clone+0x6d)[0x7f8e6df09cfd]
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(0x10bb680);
lock(0x10bb700);
lock(0x10bb680);
lock(0x10bb700);
*** DEADLOCK ***
2 locks held by ABBA_threads/12101:
#0: (&b){......}, at: tests/ABBA_threads() [0x4013bc]
#1: (0x10bb680){......}, at: tests/ABBA_threads() [0x401333]
stack backtrace:
tests/ABBA_threads[0x4016dd]
tests/ABBA_threads[0x40300b]
tests/ABBA_threads[0x4035c4]
tests/ABBA_threads[0x4039c2]
tests/ABBA_threads[0x403fde]
tests/ABBA_threads[0x404aa7]
tests/ABBA_threads[0x405565]
tests/ABBA_threads(pthread_mutex_lock+0x51)[0x4063fd]
tests/ABBA_threads[0x401333]
tests/ABBA_threads[0x4013c6]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x80a5)[0x7f8e6e1dc0a5]
/lib/x86_64-linux-gnu/libc.so.6(clone+0x6d)[0x7f8e6df09cfd]
Thanks,
Sasha
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