From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50304) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d2ezM-0007Es-7x for qemu-devel@nongnu.org; Mon, 24 Apr 2017 10:29:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1d2ezJ-0001v6-Hk for qemu-devel@nongnu.org; Mon, 24 Apr 2017 10:29:16 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:45755 helo=mx0a-001b2d01.pphosted.com) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1d2ezJ-0001u2-BM for qemu-devel@nongnu.org; Mon, 24 Apr 2017 10:29:13 -0400 Received: from pps.filterd (m0098414.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v3OET4M0139345 for ; Mon, 24 Apr 2017 10:29:11 -0400 Received: from e24smtp01.br.ibm.com (e24smtp01.br.ibm.com [32.104.18.85]) by mx0b-001b2d01.pphosted.com with ESMTP id 2a1g8qb1fg-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 24 Apr 2017 10:29:10 -0400 Received: from localhost by e24smtp01.br.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 24 Apr 2017 11:29:09 -0300 Received: from d24av03.br.ibm.com (d24av03.br.ibm.com [9.8.31.95]) by d24relay03.br.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v3OET5Y426214558 for ; Mon, 24 Apr 2017 11:29:06 -0300 Received: from d24av03.br.ibm.com (localhost [127.0.0.1]) by d24av03.br.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id v3OET6qr015628 for ; Mon, 24 Apr 2017 11:29:06 -0300 From: Jose Ricardo Ziviani Date: Mon, 24 Apr 2017 11:28:46 -0300 Message-Id: <1493044126-21488-1-git-send-email-joserz@linux.vnet.ibm.com> Subject: [Qemu-devel] [PATCH] trace: add qemu mutex lock and unlock trace events List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: stefanha@redhat.com, pbonzini@redhat.com These trace events were very useful to help me to understand and find a reordering issue in vfio, for example: qemu_mutex_lock locked mutex 0x10905ad8 vfio_region_write (0001:03:00.0:region1+0xc0, 0x2020c, 4) qemu_mutex_unlock unlocked mutex 0x10905ad8 qemu_mutex_lock locked mutex 0x10905ad8 vfio_region_write (0001:03:00.0:region1+0xc4, 0xa0000, 4) qemu_mutex_unlock unlocked mutex 0x10905ad8 that also helped to see desired result after the fix: qemu_mutex_lock locked mutex 0x10905ad8 vfio_region_write (0001:03:00.0:region1+0xc0, 0x2000c, 4) vfio_region_write (0001:03:00.0:region1+0xc4, 0xb0000, 4) qemu_mutex_unlock unlocked mutex 0x10905ad8 So it could be a good idea to have these traces implemented. It's worth mentioning that they should be surgically enabled during the debugging, otherwise it'd flood the trace logs with lock/unlock messages. How to use it: trace-event qemu_mutex_lock on|off trace-event qemu_mutex_unlock on|off or trace-event qemu_mutex* on|off Signed-off-by: Jose Ricardo Ziviani --- util/qemu-thread-posix.c | 5 +++++ util/trace-events | 4 ++++ 2 files changed, 9 insertions(+) diff --git a/util/qemu-thread-posix.c b/util/qemu-thread-posix.c index 73e3a0e..909c2ac 100644 --- a/util/qemu-thread-posix.c +++ b/util/qemu-thread-posix.c @@ -14,6 +14,7 @@ #include "qemu/thread.h" #include "qemu/atomic.h" #include "qemu/notify.h" +#include "trace.h" static bool name_threads; @@ -60,6 +61,8 @@ void qemu_mutex_lock(QemuMutex *mutex) err = pthread_mutex_lock(&mutex->lock); if (err) error_exit(err, __func__); + + trace_qemu_mutex_lock((void *)&mutex->lock); } int qemu_mutex_trylock(QemuMutex *mutex) @@ -74,6 +77,8 @@ void qemu_mutex_unlock(QemuMutex *mutex) err = pthread_mutex_unlock(&mutex->lock); if (err) error_exit(err, __func__); + + trace_qemu_mutex_unlock((void *)&mutex->lock); } void qemu_rec_mutex_init(QemuRecMutex *mutex) diff --git a/util/trace-events b/util/trace-events index b44ef4f..65c33fe 100644 --- a/util/trace-events +++ b/util/trace-events @@ -55,3 +55,7 @@ lockcnt_futex_wait_prepare(const void *lockcnt, int expected, int new) "lockcnt lockcnt_futex_wait(const void *lockcnt, int val) "lockcnt %p waiting on %d" lockcnt_futex_wait_resume(const void *lockcnt, int new) "lockcnt %p after wait: %d" lockcnt_futex_wake(const void *lockcnt) "lockcnt %p waking up one waiter" + +# util/qemu-thread-posix.c +qemu_mutex_lock(void *qemu_global_mutex) "locked mutex %p" +qemu_mutex_unlock(void *qemu_global_mutex) "unlocked mutex %p" -- 2.7.4