From nobody Sun Nov 9 14:46:30 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1550805410802675.5519842938658; Thu, 21 Feb 2019 19:16:50 -0800 (PST) Received: from localhost ([127.0.0.1]:43414 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gx1KM-00028C-B7 for importer@patchew.org; Thu, 21 Feb 2019 22:16:42 -0500 Received: from eggs.gnu.org ([209.51.188.92]:39928) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gx1Il-0001IW-IV for qemu-devel@nongnu.org; Thu, 21 Feb 2019 22:15:04 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gx1Ik-0000gx-70 for qemu-devel@nongnu.org; Thu, 21 Feb 2019 22:15:03 -0500 Received: from mx1.redhat.com ([209.132.183.28]:55594) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gx1Ij-0008VM-Fi for qemu-devel@nongnu.org; Thu, 21 Feb 2019 22:15:01 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 5644A3005FC5 for ; Fri, 22 Feb 2019 03:14:33 +0000 (UTC) Received: from xz-x1.redhat.com (ovpn-12-57.pek2.redhat.com [10.72.12.57]) by smtp.corp.redhat.com (Postfix) with ESMTP id DCA315D9D4; Fri, 22 Feb 2019 03:14:30 +0000 (UTC) From: Peter Xu To: qemu-devel@nongnu.org Date: Fri, 22 Feb 2019 11:14:10 +0800 Message-Id: <20190222031413.20250-2-peterx@redhat.com> In-Reply-To: <20190222031413.20250-1-peterx@redhat.com> References: <20190222031413.20250-1-peterx@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.40]); Fri, 22 Feb 2019 03:14:33 +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 1/4] iothread: replace init_done_cond with a semaphore 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: Paolo Bonzini , peterx@redhat.com, Stefan Hajnoczi , =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Only sending an init-done message using lock+cond seems an overkill to me. Replacing it with a simpler semaphore. Meanwhile, init the semaphore unconditionally, then we can destroy it unconditionally too in finalize which seems cleaner. Signed-off-by: Peter Xu Reviewed-by: Stefan Hajnoczi --- include/sysemu/iothread.h | 3 +-- iothread.c | 17 ++++------------- 2 files changed, 5 insertions(+), 15 deletions(-) diff --git a/include/sysemu/iothread.h b/include/sysemu/iothread.h index 8a7ac2c528..50411ba54a 100644 --- a/include/sysemu/iothread.h +++ b/include/sysemu/iothread.h @@ -27,8 +27,7 @@ typedef struct { GMainContext *worker_context; GMainLoop *main_loop; GOnce once; - QemuMutex init_done_lock; - QemuCond init_done_cond; /* is thread initialization done? */ + QemuSemaphore init_done_sem; /* is thread init done? */ bool stopping; /* has iothread_stop() been called? */ bool running; /* should iothread_run() continue? */ int thread_id; diff --git a/iothread.c b/iothread.c index e615b7ae52..6e297e9ef1 100644 --- a/iothread.c +++ b/iothread.c @@ -55,10 +55,8 @@ static void *iothread_run(void *opaque) rcu_register_thread(); =20 my_iothread =3D iothread; - qemu_mutex_lock(&iothread->init_done_lock); iothread->thread_id =3D qemu_get_thread_id(); - qemu_cond_signal(&iothread->init_done_cond); - qemu_mutex_unlock(&iothread->init_done_lock); + qemu_sem_post(&iothread->init_done_sem); =20 while (iothread->running) { aio_poll(iothread->ctx, true); @@ -115,6 +113,7 @@ static void iothread_instance_init(Object *obj) =20 iothread->poll_max_ns =3D IOTHREAD_POLL_MAX_NS_DEFAULT; iothread->thread_id =3D -1; + qemu_sem_init(&iothread->init_done_sem, 0); } =20 static void iothread_instance_finalize(Object *obj) @@ -123,10 +122,6 @@ static void iothread_instance_finalize(Object *obj) =20 iothread_stop(iothread); =20 - if (iothread->thread_id !=3D -1) { - qemu_cond_destroy(&iothread->init_done_cond); - qemu_mutex_destroy(&iothread->init_done_lock); - } /* * Before glib2 2.33.10, there is a glib2 bug that GSource context * pointer may not be cleared even if the context has already been @@ -145,6 +140,7 @@ static void iothread_instance_finalize(Object *obj) g_main_context_unref(iothread->worker_context); iothread->worker_context =3D NULL; } + qemu_sem_destroy(&iothread->init_done_sem); } =20 static void iothread_complete(UserCreatable *obj, Error **errp) @@ -173,8 +169,6 @@ static void iothread_complete(UserCreatable *obj, Error= **errp) return; } =20 - qemu_mutex_init(&iothread->init_done_lock); - qemu_cond_init(&iothread->init_done_cond); iothread->once =3D (GOnce) G_ONCE_INIT; =20 /* This assumes we are called from a thread with useful CPU affinity f= or us @@ -188,12 +182,9 @@ static void iothread_complete(UserCreatable *obj, Erro= r **errp) g_free(name); =20 /* Wait for initialization to complete */ - qemu_mutex_lock(&iothread->init_done_lock); while (iothread->thread_id =3D=3D -1) { - qemu_cond_wait(&iothread->init_done_cond, - &iothread->init_done_lock); + qemu_sem_wait(&iothread->init_done_sem); } - qemu_mutex_unlock(&iothread->init_done_lock); } =20 typedef struct { --=20 2.17.1