From nobody Tue Oct 28 02:08:43 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; 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 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1516116641963797.4030599116509; Tue, 16 Jan 2018 07:30:41 -0800 (PST) Received: from localhost ([::1]:40951 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ebTCC-0005YQ-F1 for importer@patchew.org; Tue, 16 Jan 2018 10:30:40 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52481) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ebS9D-0007xL-Jl for qemu-devel@nongnu.org; Tue, 16 Jan 2018 09:23:35 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ebS99-0007hf-MT for qemu-devel@nongnu.org; Tue, 16 Jan 2018 09:23:31 -0500 Received: from mx1.redhat.com ([209.132.183.28]:43274) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ebS99-0007hJ-Dn for qemu-devel@nongnu.org; Tue, 16 Jan 2018 09:23:27 -0500 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A55A62D1EF7 for ; Tue, 16 Jan 2018 14:23:21 +0000 (UTC) Received: from donizetti.redhat.com (ovpn-116-234.ams2.redhat.com [10.36.116.234]) by smtp.corp.redhat.com (Postfix) with ESMTP id E376F5C1AB for ; Tue, 16 Jan 2018 14:23:20 +0000 (UTC) From: Paolo Bonzini To: qemu-devel@nongnu.org Date: Tue, 16 Jan 2018 15:23:15 +0100 Message-Id: <20180116142316.30486-4-pbonzini@redhat.com> In-Reply-To: <20180116142316.30486-1-pbonzini@redhat.com> References: <20180116142316.30486-1-pbonzini@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Tue, 16 Jan 2018 14:23:26 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH 3/4] coroutine-lock: make qemu_co_enter_next thread-safe 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: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" qemu_co_queue_next does not need to release and re-acquire the mutex, because the queued coroutine does not run immediately. However, this does not hold for qemu_co_enter_next. Now that qemu_co_queue_wait can synchronize (via QemuLockable) with code that is not running in coroutine context, it's important that code using qemu_co_enter_next can easily use a standardized locking idiom. First of all, qemu_co_enter_next must use aio_co_wake to restart the coroutine. Second, the function gains a second argument, a QemuLockable*, and the comments of qemu_co_queue_next and qemu_co_queue_restart_all are adjusted to clarify the difference. Signed-off-by: Paolo Bonzini --- fsdev/qemu-fsdev-throttle.c | 4 ++-- include/qemu/coroutine.h | 15 ++++++++++----- util/qemu-coroutine-lock.c | 10 ++++++++-- 3 files changed, 20 insertions(+), 9 deletions(-) diff --git a/fsdev/qemu-fsdev-throttle.c b/fsdev/qemu-fsdev-throttle.c index 49eebb5412..1dc07fbc12 100644 --- a/fsdev/qemu-fsdev-throttle.c +++ b/fsdev/qemu-fsdev-throttle.c @@ -20,13 +20,13 @@ static void fsdev_throttle_read_timer_cb(void *opaque) { FsThrottle *fst =3D opaque; - qemu_co_enter_next(&fst->throttled_reqs[false]); + qemu_co_enter_next(&fst->throttled_reqs[false], NULL); } =20 static void fsdev_throttle_write_timer_cb(void *opaque) { FsThrottle *fst =3D opaque; - qemu_co_enter_next(&fst->throttled_reqs[true]); + qemu_co_enter_next(&fst->throttled_reqs[true], NULL); } =20 void fsdev_throttle_parse_opts(QemuOpts *opts, FsThrottle *fst, Error **er= rp) diff --git a/include/qemu/coroutine.h b/include/qemu/coroutine.h index 1e5f0957e6..6fdbc837c0 100644 --- a/include/qemu/coroutine.h +++ b/include/qemu/coroutine.h @@ -188,21 +188,26 @@ void qemu_co_queue_init(CoQueue *queue); void coroutine_fn qemu_co_queue_wait_impl(CoQueue *queue, QemuLockable *lo= ck); =20 /** - * Restarts the next coroutine in the CoQueue and removes it from the queu= e. + * Removes the next coroutine from the CoQueue; it will run as soon as the + * current one yields. * - * Returns true if a coroutine was restarted, false if the queue is empty. + * Returns true if a coroutine was removed, false if the queue is empty. */ bool coroutine_fn qemu_co_queue_next(CoQueue *queue); =20 /** - * Restarts all coroutines in the CoQueue and leaves the queue empty. + * Empties the CoQueue; all coroutines in it will run in FIFO orer as soon + * as the current one yields. */ void coroutine_fn qemu_co_queue_restart_all(CoQueue *queue); =20 /** - * Enter the next coroutine in the queue + * Immediately enter the next coroutine in the queue. Release the mutex + * while it runs. */ -bool qemu_co_enter_next(CoQueue *queue); +#define qemu_co_enter_next(queue, lock) \ + qemu_co_enter_next_impl(queue, QEMU_MAKE_LOCKABLE(lock)) +bool qemu_co_enter_next_impl(CoQueue *queue, QemuLockable *lock); =20 /** * Checks if the CoQueue is empty. diff --git a/util/qemu-coroutine-lock.c b/util/qemu-coroutine-lock.c index 2a66fc1467..78fb79acf8 100644 --- a/util/qemu-coroutine-lock.c +++ b/util/qemu-coroutine-lock.c @@ -132,7 +132,7 @@ void coroutine_fn qemu_co_queue_restart_all(CoQueue *qu= eue) qemu_co_queue_do_restart(queue, false); } =20 -bool qemu_co_enter_next(CoQueue *queue) +bool qemu_co_enter_next_impl(CoQueue *queue, QemuLockable *lock) { Coroutine *next; =20 @@ -142,7 +142,13 @@ bool qemu_co_enter_next(CoQueue *queue) } =20 QSIMPLEQ_REMOVE_HEAD(&queue->entries, co_queue_next); - qemu_coroutine_enter(next); + if (lock) { + qemu_lockable_unlock(lock); + } + aio_co_wake(next); + if (lock) { + qemu_lockable_lock(lock); + } return true; } =20 --=20 2.14.3