From patchwork Tue May 12 14:43:17 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 282945 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2E977C54E4A for ; Tue, 12 May 2020 14:45:35 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id F1F0C206A3 for ; Tue, 12 May 2020 14:45:34 +0000 (UTC) Authentication-Results: mail.kernel.org; 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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) 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 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+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" 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, CoroutineEntry *entry, void *opaque, int *ret) { if (qemu_in_coroutine()) { - /* Fast-path if already in coroutine context */ + Coroutine *self = qemu_coroutine_self(); + AioContext *bs_ctx = bdrv_get_aio_context(bs); + AioContext *co_ctx = qemu_coroutine_get_aio_context(self); + + if (bs_ctx != co_ctx) { + /* Move to the iothread of the node */ + aio_co_schedule(bs_ctx, self); + qemu_coroutine_yield(); + } entry(opaque); + if (bs_ctx != co_ctx) { + /* Move back to the original AioContext */ + aio_co_schedule(bs_ctx, self); + qemu_coroutine_yield(); + } } else { Coroutine *co = qemu_coroutine_create(entry, opaque); *ret = NOT_DONE;