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Tue, 12 May 2020 10:44:05 -0400 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-234-SblDYKekP-WGsGPfSsEMcQ-1; Tue, 12 May 2020 10:44:00 -0400 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 mimecast-mx01.redhat.com (Postfix) with ESMTPS id D9D79EC1A1; Tue, 12 May 2020 14:43:59 +0000 (UTC) Received: from linux.fritz.box.com (ovpn-114-74.ams2.redhat.com [10.36.114.74]) by smtp.corp.redhat.com (Postfix) with ESMTP id 38CB35D9DD; Tue, 12 May 2020 14:43:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1589294642; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ybxicmw62WPTarXz7cdaSgDqp3JUN9/hShkGjxRS1qg=; b=QnH7U/8jBpa9dAlltB/DkKgY8lz5jlUuW2cTtzn3QBM/gqwXH8SnYE8y1w1puMqUx5Acxj uiKUEWz5GYTBjYzhFUeojkz8GS5fRHi8E8cl/ubgg/etD4Nv5dY0xSApYBnqAEbsQ26xZC m7ozT784Ytwfr3dQyfseGwojbkW6IcA= X-MC-Unique: SblDYKekP-WGsGPfSsEMcQ-1 From: Kevin Wolf To: qemu-block@nongnu.org Subject: [RFC PATCH 2/3] block: Allow bdrv_run_co() from different AioContext Date: Tue, 12 May 2020 16:43:17 +0200 Message-Id: <20200512144318.181049-3-kwolf@redhat.com> In-Reply-To: <20200512144318.181049-1-kwolf@redhat.com> References: <20200512144318.181049-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.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; Received-SPF: pass client-ip=205.139.110.61; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/12 02:02:05 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, qemu-devel@nongnu.org, s.reiter@proxmox.com, armbru@redhat.com, mreitz@redhat.com, stefanha@redhat.com, t.lamprecht@proxmox.com Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" Coroutine functions that are entered through bdrv_run_co() are already safe to call from synchronous code in a different AioContext because bdrv_coroutine_enter() will schedule them in the context of the node. However, the coroutine fastpath still requires that we're already in the right AioContext when called in coroutine context. In order to make the behaviour more consistent and to make life a bit easier for callers, let's check the AioContext and automatically move the current coroutine around if we're not in the right context yet. Signed-off-by: Kevin Wolf --- block/io.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/block/io.c b/block/io.c index c1badaadc9..7808e8bdc0 100644 --- a/block/io.c +++ b/block/io.c @@ -895,8 +895,21 @@ static int bdrv_run_co(BlockDriverState *bs, Coroutine= Entry *entry, void *opaque, int *ret) { if (qemu_in_coroutine()) { - /* Fast-path if already in coroutine context */ + Coroutine *self =3D qemu_coroutine_self(); + AioContext *bs_ctx =3D bdrv_get_aio_context(bs); + AioContext *co_ctx =3D qemu_coroutine_get_aio_context(self); + + if (bs_ctx !=3D co_ctx) { + /* Move to the iothread of the node */ + aio_co_schedule(bs_ctx, self); + qemu_coroutine_yield(); + } entry(opaque); + if (bs_ctx !=3D co_ctx) { + /* Move back to the original AioContext */ + aio_co_schedule(bs_ctx, self); + qemu_coroutine_yield(); + } } else { Coroutine *co =3D qemu_coroutine_create(entry, opaque); *ret =3D NOT_DONE; --=20 2.25.3