From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 99E3BCEE341 for ; Tue, 18 Nov 2025 17:07:32 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vLP7Q-0000kB-NQ; Tue, 18 Nov 2025 12:03:56 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vLP7K-0000hd-Bu for qemu-devel@nongnu.org; Tue, 18 Nov 2025 12:03:46 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vLP7I-0004ql-Gd for qemu-devel@nongnu.org; Tue, 18 Nov 2025 12:03:46 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1763485423; 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=RE/4zH9RR79g8ij8X4dGR2gR7vQk03dSUvTg97qFcAI=; b=Iz0Ksn/oe4zDb6QSLs7ySlq1a/tgMncFSGF+kAhzuSg6mezdFVKn0XK1c7YsIT9mFIPbri lvSX1J/oSkZzXM5S7I+As3IsE14C4pFEtDOEsuCGk4Vcig4J8nqJ+MVN2GWgXSjC7IqAhp //EQRan0GlGW9mYwXBlLt39UElYx7pM= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-117-vTH9o_mDONOPagyCj6wV2g-1; Tue, 18 Nov 2025 12:03:39 -0500 X-MC-Unique: vTH9o_mDONOPagyCj6wV2g-1 X-Mimecast-MFC-AGG-ID: vTH9o_mDONOPagyCj6wV2g_1763485418 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 73A111800451; Tue, 18 Nov 2025 17:03:38 +0000 (UTC) Received: from merkur.fritz.box (unknown [10.44.32.26]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id DEF8B300ABAF; Tue, 18 Nov 2025 17:03:36 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, richard.henderson@linaro.org, qemu-devel@nongnu.org Subject: [PULL 16/19] block: Note in which AioContext AIO CBs are called Date: Tue, 18 Nov 2025 18:02:53 +0100 Message-ID: <20251118170256.272087-17-kwolf@redhat.com> In-Reply-To: <20251118170256.272087-1-kwolf@redhat.com> References: <20251118170256.272087-1-kwolf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 Received-SPF: pass client-ip=170.10.129.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com 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_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org From: Hanna Czenczek This doesn’t seem to be specified anywhere, but is something we probably want to be clear. I believe it is reasonable to implicitly assume that callbacks are run in the current thread (unless explicitly noted otherwise), so codify that assumption. Some implementations don’t actually fulfill this contract yet. The next patches should rectify that. Note: I don’t know of any user-visible bugs produced by not running AIO callbacks in the original context. AIO functionality is generally mapped to coroutines through the use of bdrv_co_io_em_complete(), which can run in any AioContext, and will always wake the yielding coroutine in its original context. The only benefit here is that running bdrv_co_io_em_complete() in the original context will make that aio_co_wake() most likely a simpler qemu_coroutine_enter() instead of scheduling the wakeup through AioContext.co_schedule_bh. Signed-off-by: Hanna Czenczek Message-ID: <20251110154854.151484-17-hreitz@redhat.com> Reviewed-by: Stefan Hajnoczi Reviewed-by: Kevin Wolf Signed-off-by: Kevin Wolf --- include/block/block_int-common.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h index f2a4e863fc..cb0143ea77 100644 --- a/include/block/block_int-common.h +++ b/include/block/block_int-common.h @@ -508,7 +508,12 @@ struct BlockDriver { BlockDriverState *bs, BlockdevAmendOptions *opts, bool force, Error **errp); - /* aio */ + /* + * AIO + * The given completion callback will be run in the same AioContext as the + * one in which the AIO function was called. + */ + BlockAIOCB * GRAPH_RDLOCK_PTR (*bdrv_aio_preadv)(BlockDriverState *bs, int64_t offset, int64_t bytes, QEMUIOVector *qiov, BdrvRequestFlags flags, BlockCompletionFunc *cb, void *opaque); -- 2.51.1