From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59516) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VBxlO-0002Mo-Fv for qemu-devel@nongnu.org; Tue, 20 Aug 2013 22:03:16 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VBxlI-0006aw-Gk for qemu-devel@nongnu.org; Tue, 20 Aug 2013 22:03:10 -0400 Received: from mx1.redhat.com ([209.132.183.28]:6017) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VBxlI-0006aU-9I for qemu-devel@nongnu.org; Tue, 20 Aug 2013 22:03:04 -0400 From: Asias He Date: Wed, 21 Aug 2013 10:02:47 +0800 Message-Id: <1377050567-19122-1-git-send-email-asias@redhat.com> Subject: [Qemu-devel] [PATCH] block: Fix race in gluster_finish_aiocb List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Kevin Wolf , Vijay Bellur , Stefan Hajnoczi , Bharata B Rao , Asias He , MORITA Kazutaka In block/gluster.c, we have gluster_finish_aiocb { if (retval != sizeof(acb)) { qemu_mutex_lock_iothread(); /* We are in gluster thread context */ ... qemu_mutex_unlock_iothread(); } } qemu tools, e.g. qemu-img, might race here because qemu_mutex_{lock,unlock}_iothread are a nop operation and gluster_finish_aiocb is in the gluster thread context. To fix, we introduce our own mutex for qemu tools. Signed-off-by: Asias He --- stubs/iothread-lock.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/stubs/iothread-lock.c b/stubs/iothread-lock.c index 5d8aca1..d5c6dec 100644 --- a/stubs/iothread-lock.c +++ b/stubs/iothread-lock.c @@ -1,10 +1,21 @@ #include "qemu-common.h" #include "qemu/main-loop.h" +static QemuMutex qemu_tools_mutex; +static pthread_once_t qemu_tools_once = PTHREAD_ONCE_INIT; + +static void qemu_tools_mutex_init(void) +{ + qemu_mutex_init(&qemu_tools_mutex); +} + void qemu_mutex_lock_iothread(void) { + pthread_once(&qemu_tools_once, qemu_tools_mutex_init); + qemu_mutex_lock(&qemu_tools_mutex); } void qemu_mutex_unlock_iothread(void) { + qemu_mutex_unlock(&qemu_tools_mutex); } -- 1.8.3.1