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 8AC72C44512 for ; Thu, 16 Jul 2026 15:12:08 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1wkNkF-0005Dx-5q; Thu, 16 Jul 2026 11:11:27 -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 1wkNkD-0005DW-Sg for qemu-devel@nongnu.org; Thu, 16 Jul 2026 11:11:25 -0400 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 1wkNkA-0004xv-LT for qemu-devel@nongnu.org; Thu, 16 Jul 2026 11:11:25 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1784214680; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:in-reply-to:in-reply-to: references:references; bh=YFsxFnklmO+X5ASco9yOrMosB76tHtUzWdpaJDXp+Ng=; b=RNaoDdgvFU01O2BLow1eZdQh3P4yE0/hJ3pPmuvy+KziY349kf6L9xzPARwa0iD12Ich9L jPCUTfW+ga1KvAEgflJanbQhDOxk9SWXR5cZtzIsKR1Cfseg5UnVIuhVGstNtYq/u8T4cn tPhNPbahqbMg0jZl+OySg6nYp9ocmIA= Received: from mx-prod-mc-05.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-63-DaFYEHUSPdGxIXK9m4JXfg-1; Thu, 16 Jul 2026 11:11:19 -0400 X-MC-Unique: DaFYEHUSPdGxIXK9m4JXfg-1 X-Mimecast-MFC-AGG-ID: DaFYEHUSPdGxIXK9m4JXfg_1784214677 Received: from mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.95]) (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-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 5C29D1955DC7; Thu, 16 Jul 2026 15:11:17 +0000 (UTC) Received: from redhat.com (unknown [10.44.34.221]) by mx-prod-int-10.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 8B85242E; Thu, 16 Jul 2026 15:11:12 +0000 (UTC) Date: Thu, 16 Jul 2026 16:11:09 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Zhang Chen Cc: qemu-devel , "Dr . David Alan Gilbert" , Eric Blake , Markus Armbruster , "Michael S . Tsirkin" , Stefan Hajnoczi , Paolo Bonzini , Kevin Wolf , Jason Wang , Fam Zheng Subject: Re: [PATCH V10 06/15] monitor: Update tracking iothread users with holder Message-ID: References: <20260716144043.76414-1-zhangckid@gmail.com> <20260716144043.76414-7-zhangckid@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260716144043.76414-7-zhangckid@gmail.com> User-Agent: Mutt/2.4.0 (2026-06-19) X-Scanned-By: MIMEDefang 3.6 on 10.30.177.95 Received-SPF: permerror client-ip=170.10.129.124; envelope-from=berrange@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_H2=-0.01, RCVD_IN_SBL_CSS=3.335, SPF_HELO_PASS=-0.001, T_SPF_PERMERROR=0.01 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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Thu, Jul 16, 2026 at 10:40:31PM +0800, Zhang Chen wrote: > Based on monitor QOM path tracking iothread users with holder. > Introduce the AioContext in the Monitor struct to avoid repeated calls to > iothread_get_aio_context() and ensure symmetrical ref/unref during > monitor lifecycle. > > Signed-off-by: Zhang Chen > --- > monitor/monitor-internal.h | 3 +++ > monitor/monitor.c | 22 ++++++++++++++++++++-- > monitor/qmp.c | 5 +++-- > 3 files changed, 26 insertions(+), 4 deletions(-) > > diff --git a/monitor/monitor-internal.h b/monitor/monitor-internal.h > index 23829f32f9..caecceec93 100644 > --- a/monitor/monitor-internal.h > +++ b/monitor/monitor-internal.h > @@ -153,6 +153,9 @@ struct Monitor { > guint out_watch; > int mux_out; > int reset_seen; > + > + /* iothread context */ > + AioContext *ctx; > }; > > struct MonitorHMPClass { > diff --git a/monitor/monitor.c b/monitor/monitor.c > index ed195fd97b..688bb85c81 100644 > --- a/monitor/monitor.c > +++ b/monitor/monitor.c > @@ -573,7 +573,7 @@ void monitor_suspend(Monitor *mon) > * Kick I/O thread to make sure this takes effect. It'll be > * evaluated again in prepare() of the watch object. > */ > - aio_notify(iothread_get_aio_context(mon_iothread)); > + aio_notify(mon->ctx); > } > > trace_monitor_suspend(mon, 1); > @@ -668,6 +668,17 @@ void monitor_cleanup(void) > qemu_mutex_unlock(&monitor_lock); > monitor_flush(mon); > qemu_mutex_lock(&monitor_lock); > + > + if (mon_iothread) { > + g_autofree char *path = object_get_canonical_path(OBJECT(mon)); > + const IOThreadHolder io_holder = { > + .type = IO_THREAD_HOLDER_KIND_QOM_OBJECT, > + .u.qom_object.qom_path = path, > + }; > + > + iothread_put_aio_context(mon_iothread, &io_holder); > + mon->ctx = NULL; > + } > object_unparent(OBJECT(mon)); > } > qemu_mutex_unlock(&monitor_lock); > @@ -732,7 +743,14 @@ static void monitor_complete(UserCreatable *uc, Error **errp) > mon_iothread = iothread_create("mon_iothread", &error_abort); > } > > - ctx = iothread_get_aio_context(mon_iothread); > + g_autofree char *path = object_get_canonical_path(OBJECT(mon)); > + const IOThreadHolder io_holder = { > + .type = IO_THREAD_HOLDER_KIND_QOM_OBJECT, > + .u.qom_object.qom_path = path, > + }; > + > + mon->ctx = iothread_ref_and_get_aio_context(mon_iothread, &io_holder); > + ctx = mon->ctx; > } else { > ctx = qemu_get_aio_context(); > } Even though QMP only takes the first branch, I'd be more comfortable if we set mon->ctx in both branches of this condition, so we can always assume that mon->ctx is non-NULL. > diff --git a/monitor/qmp.c b/monitor/qmp.c > index 223e0643c2..b16bd77688 100644 > --- a/monitor/qmp.c > +++ b/monitor/qmp.c > @@ -732,7 +732,8 @@ static void monitor_qmp_complete(UserCreatable *uc, Error **errp) > * thread. Schedule a bottom half. > */ > mon->setup_pending = true; > - aio_bh_schedule_oneshot(iothread_get_aio_context(mon_iothread), > + > + aio_bh_schedule_oneshot(MONITOR(mon)->ctx, > monitor_qmp_setup_handlers_bh, mon); > /* The bottom half will add @mon to @mon_list */ > } else { > @@ -787,7 +788,7 @@ static bool monitor_qmp_prepare_delete(UserCreatable *uc, Error **errp) > > /* Synchronize with in-flight iothread callbacks. */ > if (monitor_requires_iothread(mon)) { > - aio_wait_bh_oneshot(iothread_get_aio_context(mon_iothread), > + aio_wait_bh_oneshot(MONITOR(mon)->ctx, > monitor_qmp_iothread_quiesce, NULL); > } ...this unconditionally accesses mon->ctx, and so will surely hit a NULL > > -- > 2.49.0 > With regards, Daniel -- |: https://berrange.com ~~ https://hachyderm.io/@berrange :| |: https://libvirt.org ~~ https://entangle-photo.org :| |: https://pixelfed.art/berrange ~~ https://fstop138.berrange.com :|