From patchwork Mon Sep 5 18:13:44 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 666000 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3sSdsF6trKz9s9Y for ; Tue, 6 Sep 2016 04:43:13 +1000 (AEST) Received: from localhost ([::1]:56290 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bgyrO-00023J-Ln for incoming@patchwork.ozlabs.org; Mon, 05 Sep 2016 14:43:10 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38465) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bgyPt-0003DC-JG for qemu-devel@nongnu.org; Mon, 05 Sep 2016 14:14:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bgyPs-00016V-NL for qemu-devel@nongnu.org; Mon, 05 Sep 2016 14:14:45 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51408) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bgyPl-00013H-Kl; Mon, 05 Sep 2016 14:14:37 -0400 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 540AF8535A; Mon, 5 Sep 2016 18:14:37 +0000 (UTC) Received: from noname.redhat.com (ovpn-116-62.ams2.redhat.com [10.36.116.62]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u85IDt7u020627; Mon, 5 Sep 2016 14:14:36 -0400 From: Kevin Wolf To: qemu-block@nongnu.org Date: Mon, 5 Sep 2016 20:13:44 +0200 Message-Id: <1473099234-10882-33-git-send-email-kwolf@redhat.com> In-Reply-To: <1473099234-10882-1-git-send-email-kwolf@redhat.com> References: <1473099234-10882-1-git-send-email-kwolf@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Mon, 05 Sep 2016 18:14:37 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL 32/42] coroutine: Let CoMutex remember who holds it X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" In cases of deadlocks, knowing who holds a given CoMutex is really helpful for debugging. Keeping the information around doesn't cost much and allows us to add another assertion to keep the code correct, so let's just add it. Signed-off-by: Kevin Wolf Reviewed-by: Paolo Bonzini Reviewed-by: Stefan Hajnoczi --- include/qemu/coroutine.h | 1 + util/qemu-coroutine-lock.c | 3 +++ 2 files changed, 4 insertions(+) diff --git a/include/qemu/coroutine.h b/include/qemu/coroutine.h index ac8d4c9..29a2078 100644 --- a/include/qemu/coroutine.h +++ b/include/qemu/coroutine.h @@ -143,6 +143,7 @@ bool qemu_co_queue_empty(CoQueue *queue); */ typedef struct CoMutex { bool locked; + Coroutine *holder; CoQueue queue; } CoMutex; diff --git a/util/qemu-coroutine-lock.c b/util/qemu-coroutine-lock.c index 22aa9ab..f30ee81 100644 --- a/util/qemu-coroutine-lock.c +++ b/util/qemu-coroutine-lock.c @@ -129,6 +129,7 @@ void coroutine_fn qemu_co_mutex_lock(CoMutex *mutex) } mutex->locked = true; + mutex->holder = self; trace_qemu_co_mutex_lock_return(mutex, self); } @@ -140,9 +141,11 @@ void coroutine_fn qemu_co_mutex_unlock(CoMutex *mutex) trace_qemu_co_mutex_unlock_entry(mutex, self); assert(mutex->locked == true); + assert(mutex->holder == self); assert(qemu_in_coroutine()); mutex->locked = false; + mutex->holder = NULL; qemu_co_queue_next(&mutex->queue); trace_qemu_co_mutex_unlock_return(mutex, self);