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 C919DFF886F for ; Thu, 30 Apr 2026 09:24:46 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1wINdL-0001IN-W0; Thu, 30 Apr 2026 05:24:36 -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 1wINdJ-0001GD-8v for qemu-devel@nongnu.org; Thu, 30 Apr 2026 05:24:33 -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 1wINdH-00079h-O3 for qemu-devel@nongnu.org; Thu, 30 Apr 2026 05:24:33 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1777541069; 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=BhzmE3u3CLkUJhsld6R8ow20RZ1LxbQpFZFMvQSuSY8=; b=FThLdQwH3ZHSPduXps9S8VyBKEyhjmw+sUL0dOpbZVAMkngqREJowMR9kBPblGu3a7POaw KO7zt6L6KzhEooz+mNBQlD4Hl9P5Mnr8JJhklkOvKCZLIT7BVhS5RIfSBR6rhyPYsxySqw au4dTjd56DWoTWyg5FK65BGoJ3jZfIY= Received: from mx-prod-mc-06.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-654-ciSBvCZYOm6sNg3moSZVgQ-1; Thu, 30 Apr 2026 05:24:26 -0400 X-MC-Unique: ciSBvCZYOm6sNg3moSZVgQ-1 X-Mimecast-MFC-AGG-ID: ciSBvCZYOm6sNg3moSZVgQ_1777541065 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-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 269F3180034C; Thu, 30 Apr 2026 09:24:25 +0000 (UTC) Received: from redhat.com (unknown [10.44.48.62]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id A5805300019F; Thu, 30 Apr 2026 09:24:23 +0000 (UTC) Date: Thu, 30 Apr 2026 10:24:20 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Richard Henderson Cc: qemu-devel@nongnu.org Subject: Re: [PATCH 1/3] qom/object: merge double hash table traversal in object_property_del_child Message-ID: References: <20260429062004.36582-1-guobin@linux.alibaba.com> <20260429062004.36582-2-guobin@linux.alibaba.com> <81772bda-5aed-43a0-ab2d-ac9b95b518d5@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <81772bda-5aed-43a0-ab2d-ac9b95b518d5@linaro.org> User-Agent: Mutt/2.3.1 (2026-03-20) X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham 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, Apr 30, 2026 at 07:07:03AM +1000, Richard Henderson wrote: > On 4/29/26 16:20, Bin Guo wrote: > > object_property_del_child() previously performed two full iterations > > over obj->properties: the first to find the matching child property and > > call its release callback, the second to find the same property again > > and remove it from the hash table. > > > > Merge the two loops into one: when the matching property is found, call > > the release callback and immediately remove the entry via > > g_hash_table_iter_remove(), then break. This halves the number of hash > > table operations in the common case and avoids the redundant second scan. > > > > Signed-off-by: Bin Guo > > --- > > qom/object.c | 7 ------- > > 1 file changed, 7 deletions(-) > > > > diff --git a/qom/object.c b/qom/object.c > > index f981e27044..9c0e8dfd02 100644 > > --- a/qom/object.c > > +++ b/qom/object.c > > @@ -629,13 +629,6 @@ static void object_property_del_child(Object *obj, Object *child) > > prop->release(obj, prop->name, prop->opaque); > > prop->release = NULL; > > } > > - break; > > - } > > - } > > - g_hash_table_iter_init(&iter, obj->properties); > > - while (g_hash_table_iter_next(&iter, &key, &value)) { > > - prop = value; > > - if (object_property_is_child(prop) && prop->opaque == child) { > > g_hash_table_iter_remove(&iter); > > break; > > } > > Fixes: b604a854e84 ("qom: Replace object property list with GHashTable") On the contrary, this proposed patch breaks that commit. The original proposal for that old commit had a single iteration, but it was discovered that this broke cleanup for certain devices, as prop->release can have side-effects that trigger assertions in g_hash_table_iter_remove. This requires a two phase iteration to be safe. A test for that problem was added in 8c4d156c187c84b574d287bd4b9ddf9a6975de7c and this new patch proposal duly breaks the check-qom-proplist test. With regards, Daniel