From patchwork Thu Aug 11 16:22:22 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 658292 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 3s9CyB2NPvz9sCj for ; Fri, 12 Aug 2016 02:24:02 +1000 (AEST) Received: from localhost ([::1]:49660 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bXsm0-0005mT-0O for incoming@patchwork.ozlabs.org; Thu, 11 Aug 2016 12:24:00 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44738) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bXsko-00040I-EN for qemu-devel@nongnu.org; Thu, 11 Aug 2016 12:22:47 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bXskn-0004Qx-8y for qemu-devel@nongnu.org; Thu, 11 Aug 2016 12:22:46 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47604) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bXski-0004PF-P4; Thu, 11 Aug 2016 12:22:40 -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 5FFEC66844; Thu, 11 Aug 2016 16:22:40 +0000 (UTC) Received: from noname.redhat.com (ovpn-116-88.ams2.redhat.com [10.36.116.88]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u7BGMZji017817; Thu, 11 Aug 2016 12:22:39 -0400 From: Kevin Wolf To: qemu-block@nongnu.org Date: Thu, 11 Aug 2016 18:22:22 +0200 Message-Id: <1470932542-12311-3-git-send-email-kwolf@redhat.com> In-Reply-To: <1470932542-12311-1-git-send-email-kwolf@redhat.com> References: <1470932542-12311-1-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]); Thu, 11 Aug 2016 16:22:40 +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] [PATCH 2/2] coroutine: Assert that no locks are held on termination 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, pbonzini@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" A coroutine that takes a lock must also release it again. If the coroutine terminates without having released all its locks, it's buggy and we'll probably run into a deadlock sooner or later. Make sure that we don't get such cases. Signed-off-by: Kevin Wolf --- include/qemu/coroutine_int.h | 1 + util/qemu-coroutine-lock.c | 11 +++++++++++ util/qemu-coroutine.c | 1 + 3 files changed, 13 insertions(+) diff --git a/include/qemu/coroutine_int.h b/include/qemu/coroutine_int.h index 581a7f5..6df9d33 100644 --- a/include/qemu/coroutine_int.h +++ b/include/qemu/coroutine_int.h @@ -39,6 +39,7 @@ struct Coroutine { void *entry_arg; Coroutine *caller; QSLIST_ENTRY(Coroutine) pool_next; + size_t locks_held; /* Coroutines that should be woken up when we yield or terminate */ QSIMPLEQ_HEAD(, Coroutine) co_queue_wakeup; diff --git a/util/qemu-coroutine-lock.c b/util/qemu-coroutine-lock.c index f30ee81..14cf9ce 100644 --- a/util/qemu-coroutine-lock.c +++ b/util/qemu-coroutine-lock.c @@ -130,6 +130,7 @@ void coroutine_fn qemu_co_mutex_lock(CoMutex *mutex) mutex->locked = true; mutex->holder = self; + self->locks_held++; trace_qemu_co_mutex_lock_return(mutex, self); } @@ -146,6 +147,7 @@ void coroutine_fn qemu_co_mutex_unlock(CoMutex *mutex) mutex->locked = false; mutex->holder = NULL; + self->locks_held--; qemu_co_queue_next(&mutex->queue); trace_qemu_co_mutex_unlock_return(mutex, self); @@ -159,14 +161,19 @@ void qemu_co_rwlock_init(CoRwlock *lock) void qemu_co_rwlock_rdlock(CoRwlock *lock) { + Coroutine *self = qemu_coroutine_self(); + while (lock->writer) { qemu_co_queue_wait(&lock->queue); } lock->reader++; + self->locks_held++; } void qemu_co_rwlock_unlock(CoRwlock *lock) { + Coroutine *self = qemu_coroutine_self(); + assert(qemu_in_coroutine()); if (lock->writer) { lock->writer = false; @@ -179,12 +186,16 @@ void qemu_co_rwlock_unlock(CoRwlock *lock) qemu_co_queue_next(&lock->queue); } } + self->locks_held--; } void qemu_co_rwlock_wrlock(CoRwlock *lock) { + Coroutine *self = qemu_coroutine_self(); + while (lock->writer || lock->reader) { qemu_co_queue_wait(&lock->queue); } lock->writer = true; + self->locks_held++; } diff --git a/util/qemu-coroutine.c b/util/qemu-coroutine.c index 89f21a9..3cbf225 100644 --- a/util/qemu-coroutine.c +++ b/util/qemu-coroutine.c @@ -122,6 +122,7 @@ void qemu_coroutine_enter(Coroutine *co) case COROUTINE_YIELD: return; case COROUTINE_TERMINATE: + assert(!co->locks_held); trace_qemu_coroutine_terminate(co); coroutine_delete(co); return;