From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966555AbbDWQSP (ORCPT ); Thu, 23 Apr 2015 12:18:15 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:42876 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966283AbbDWQSO (ORCPT ); Thu, 23 Apr 2015 12:18:14 -0400 Message-ID: <55391B3C.60108@oracle.com> Date: Thu, 23 Apr 2015 12:18:04 -0400 From: Sasha Levin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-Version: 1.0 To: eunb.song@samsung.com CC: "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] tools/liblockdep: change current_obj from thread-local storage to non thread-local storage References: <1635690742.249841429772120132.JavaMail.weblogic@epmlwas03d> In-Reply-To: <1635690742.249841429772120132.JavaMail.weblogic@epmlwas03d> Content-Type: text/plain; charset=euc-kr Content-Transfer-Encoding: 7bit X-Source-IP: aserv0022.oracle.com [141.146.126.234] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 #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