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 lists1p.gnu.org (lists1p.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 2D7A4C79F8C for ; Wed, 9 Sep 2026 10:42:08 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1x4FkR-0001qp-Hu; Wed, 09 Sep 2026 06:41:47 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1x4FkQ-0001qO-2U for qemu-devel@nongnu.org; Wed, 09 Sep 2026 06:41:46 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1x4FkO-0002Rl-Iz for qemu-devel@nongnu.org; Wed, 09 Sep 2026 06:41:45 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1788950503; 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=8zaOUwy1a6as5Flcg2yEZa5MseELqYhBAEHnIpjVOMQ=; b=HuCBGnTGEBrReEN0mJM+HUgWMI5AJP+oMN9wcPyT2jLXJ8u8SvKD0KDoa3X3OOnkdIJSSk CFSO9exztxdcdrNqPA3y+jUSGaXZlgb/C0iWikBnRbZYUHOyc0LNlT5YwwhqVhuW+yfoiP QInYBQ0QmSHfZMlL5Ob85VCVWdDL87A= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-14-NoKrpFgCMtiGfQv35-N4Xw-1; Wed, 09 Sep 2026 06:41:42 -0400 X-MC-Unique: NoKrpFgCMtiGfQv35-N4Xw-1 X-Mimecast-MFC-AGG-ID: NoKrpFgCMtiGfQv35-N4Xw_1788950501 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-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id CFB551955E7B; Wed, 9 Sep 2026 10:41:40 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.44.22.5]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 890A130001BB; Wed, 9 Sep 2026 10:41:40 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 4493621E6A04; Wed, 09 Sep 2026 12:41:38 +0200 (CEST) From: Markus Armbruster To: Zhang Chen Cc: qemu-devel , Eric Blake , "Michael S . Tsirkin" , Stefan Hajnoczi , Paolo Bonzini , Daniel P . =?utf-8?Q?Berrang=C3=A9?= , Jason Wang Subject: Re: [PATCH V15 13/14] iothread: make legacy AioContext getter explicitly unsafe In-Reply-To: (Zhang Chen's message of "Wed, 9 Sep 2026 14:24:03 +0800") References: <20260907063725.626685-1-zhangckid@gmail.com> <20260907063725.626685-14-zhangckid@gmail.com> <87zextw78o.fsf@pond.sub.org> Date: Wed, 09 Sep 2026 12:41:38 +0200 Message-ID: <87bja6n1ul.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 Received-SPF: pass client-ip=170.10.133.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: 12 X-Spam_score: 1.2 X-Spam_bar: + X-Spam_report: (1.2 / 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_SBL_CSS=3.335, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development 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 Zhang Chen writes: > On Mon, Sep 7, 2026 at 8:55=E2=80=AFPM Markus Armbruster wrote: >> >> Zhang Chen writes: >> >> > Now that holder-aware callers have been converted, rename >> > iothread_get_aio_context() to iothread_unsafe_get_aio_context() and >> > update qmp_x_blockdev_set_iothread(). This avoids adding a duplicate >> > accessor only to remove the old one later. >> >> The last sentence appears to justify the change since v14. If that's >> the intent, drop it, please. If not, what is the intent? > > Thanks. Yes, that sentence was about the changes since v14; I'll > drop it from the commit message. > >> >> > The block graph retains only the AioContext, while detachment happens >> > outside qmp_x_blockdev_set_iothread(), so this call site cannot provide >> > a matching holder lifecycle. The new name makes its existing lifetime >> > assumption explicit. >> >> Suggest to start like "The only remaining user is >> qmp_x_blockdev_set_iothread()" and then explain why this caller cannot >> use iothread_ref_and_get_aio_context(). >> >> > New code should use iothread_ref_and_get_aio_context(). >> > >> > Reviewed-by: Stefan Hajnoczi >> > Signed-off-by: Zhang Chen >> > --- >> > blockdev.c | 7 ++++++- >> > include/system/iothread.h | 11 ++++++++++- >> > iothread.c | 2 +- >> > 3 files changed, 17 insertions(+), 3 deletions(-) >> > >> > diff --git a/blockdev.c b/blockdev.c >> > index 6e86c6262f..97d161079a 100644 >> > --- a/blockdev.c >> > +++ b/blockdev.c >> > @@ -3683,7 +3683,12 @@ void qmp_x_blockdev_set_iothread(const char *no= de_name, StrOrNull *iothread, >> > goto out; >> > } >> > >> > - new_context =3D iothread_get_aio_context(obj); >> > + /* >> > + * The block graph retains only the AioContext, not the IOThr= ead. >> > + * Context detachment happens outside this command, so there = is no >> > + * point here where a matching IOThread holder can be release= d. >> > + */ >> >> This is fine for readers who already know what this is about: why we >> can't use iothread_ref_and_get_aio_context() / >> iothread_unsafe_get_aio_context() here. Others will lack context. >> >> Suggest to start like >> >> /* >> * We cannot use iothread_ref_and_get_aio_context() / >> * iothread_unref_and_put_aio_context() here. >> >> then explain why. > > OK, will change it to: > /* > * We cannot use iothread_ref_and_get_aio_context() / > * iothread_unref_and_put_aio_context() here. The block graph stores > * the AioContext but not the IOThread, and continues using the > * context after this command returns. A matching put would need > * to be tied to the block graph's context lifecycle. > */ Works for me, thanks!