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 08DB9D5B172 for ; Mon, 15 Dec 2025 14:53:40 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vV9wC-000317-LN; Mon, 15 Dec 2025 09:52:36 -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 1vV9wB-00030o-Ke for qemu-devel@nongnu.org; Mon, 15 Dec 2025 09:52:35 -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 1vV9w9-0008Pu-MM for qemu-devel@nongnu.org; Mon, 15 Dec 2025 09:52:35 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1765810352; 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:autocrypt:autocrypt; bh=zF8JgN4tWbVCAWjS2x+UG6gULrYPoT5c49LyU7Nv77s=; b=d9CUk2Jo/ok5gs0BTzfaUnfPfgdOJXoibSODuPe4eACCa0OjLkqSL4OI7H+i/VIxX77R6S IhVOGml3dnt3xT3egy42nIVPv81mESr7yEpfbiLutGHCk+hUONECi6W2wt2sm4bgysHUxw VgXTi2xR3ySg3Anj/sDc6bpXhF8uVjQ= Received: from mail-ej1-f69.google.com (mail-ej1-f69.google.com [209.85.218.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-591-enIjNg1FMz-AIBHnXJE8UA-1; Mon, 15 Dec 2025 09:52:31 -0500 X-MC-Unique: enIjNg1FMz-AIBHnXJE8UA-1 X-Mimecast-MFC-AGG-ID: enIjNg1FMz-AIBHnXJE8UA_1765810350 Received: by mail-ej1-f69.google.com with SMTP id a640c23a62f3a-b7fe37056e1so50859466b.2 for ; Mon, 15 Dec 2025 06:52:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1765810350; x=1766415150; darn=nongnu.org; h=content-transfer-encoding:in-reply-to:autocrypt:content-language :from:references:cc:to:subject:user-agent:mime-version:date :message-id:from:to:cc:subject:date:message-id:reply-to; bh=zF8JgN4tWbVCAWjS2x+UG6gULrYPoT5c49LyU7Nv77s=; b=YhdH5ukMTxQFhm5DL/dhb9PWQhMrLNyLUXQ0E4N8lgozmERPZO3uzxtx165cZfp1G4 87CBG+Mwh6+ftknfnygoGOyXFR4b35e+lZa+RnYykx1YHMyhwXGZSGctDszmdBEo9I/2 tT5RlGb4QM7TGPnuNNySczstGRMMLK1dr/nHEuIjYq0CNakCq2AAEIURu9hk+xbZZELA 9Ngf+nIio+6eyq1+qofsfuwSyEtzYuDMI7qjNJAfvHh2Vq2eWF54hYuBBuvEW+wUoAFh dPOZSDjaYYTQ51b9rG+M//BMdmTLfz9IPASXJ75VfpuU31/p4ElBpglCXDbv8Bwa70dA fRbg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1765810350; x=1766415150; h=content-transfer-encoding:in-reply-to:autocrypt:content-language :from:references:cc:to:subject:user-agent:mime-version:date :message-id:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=zF8JgN4tWbVCAWjS2x+UG6gULrYPoT5c49LyU7Nv77s=; b=soO8BIwhFYESJAbqlIScfomUv7F6XDUrz8xXAdSdSSHVCmgqp0gerqbbpzD+plUHgg hO/39hFgH+iD0knsJ9+WOiKUQzHGweAWP2DCzMvc6d9dN6hmHi05GpQdDrxTcisMakK3 qTRJmB/+FbKN1LKgnSPUam7xQHXTvc/xgMCBqV+zOsShbtLsP4MK5DXcVkJ7urnDg+zW zfnIpulgAaxhx74VbJDZxBbzsEGDuJctzX/bcKKn2OWhCSYbhiXwzKQnYtfllX29ESbB 7UtrDDuABlFNU/iRYxdXkEe24DanCXvRMds01G8Vb1/d4p+GdmizpBNZfX7fMoeCkhD6 lzXg== X-Forwarded-Encrypted: i=1; AJvYcCVsz0KOY3PUZI6iCP1gy9nSh48a2ButUIdxpTpCwM2v6ODMR4xCLXi5PDTLH08Z9YfngOuYVbN9QeyQ@nongnu.org X-Gm-Message-State: AOJu0YwkcKYvXnN4KUTWEaOJL7Emeq5SZ0PtnZyfS5tbHlhAYGTdNujF Yc22J3m9ng4RH2ZY2wFxb3aPu598jsIccbs7P6rJYH1JSezWv0lDK+SHwZQDyXldJ7pKAQESanJ wj4v8n1NOhvTitGuBhB1V8rpeLyahRpTb/p7vxgBGE9TQwj0+CZdqyI60 X-Gm-Gg: AY/fxX5/2OPiN6SgUVjlWDKHxPmasezRK/I8G7s+wtZ7tpQ6xAvqiuiYNcVjAPWOLRO cgWeMfiBTt148KRGbC+Gc/Nq+jsaLsbx9etAzHlpmrwOZ5pgIL5cg3VKSykZRR545J+BHtuOfDb 2Qz4Y8tI0iRAJRO0UEU7NeuWRH148cmyE6V9Ay7foh7Mh9Fahvx71177B7BBjN5Kf7CLPCxbKX/ uFoHZInZloqcBpdzlNloZp0KoEkAmPShSifu0t4wcDM+18FBcX5SShZW/TIgrQ+Dgbj9PJLrfRQ SvtmfHSM5XPWJd32MOob5vgXKTxMeJpGU8zujQ5iiv2c1UA1/S/28bskvS3EjbL3NMnE3yeNsfS sbdRUg2Q1lY57fMDDQaKZlDTGAR0WvWwxxpa4Y90idJZh2/FHePEAScf5QNi4f7QxHefg4voHXX oYygI4rNeL0aYQW2k= X-Received: by 2002:a17:907:2d29:b0:b70:c190:62e1 with SMTP id a640c23a62f3a-b7d23ad635bmr1137591266b.35.1765810349949; Mon, 15 Dec 2025 06:52:29 -0800 (PST) X-Google-Smtp-Source: AGHT+IHn8J0an9IDgB1tsnPyFoLwVTjx3kNnmLGSz0vmlk7BO5WUjHzTh7WRzivAGmyoQORHhuQEcw== X-Received: by 2002:a17:907:2d29:b0:b70:c190:62e1 with SMTP id a640c23a62f3a-b7d23ad635bmr1137588366b.35.1765810349548; Mon, 15 Dec 2025 06:52:29 -0800 (PST) Received: from [192.168.10.48] ([151.95.145.106]) by smtp.googlemail.com with ESMTPSA id a640c23a62f3a-b7cfa2ed80dsm1416551566b.16.2025.12.15.06.52.28 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 15 Dec 2025 06:52:29 -0800 (PST) Message-ID: Date: Mon, 15 Dec 2025 15:52:27 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 3/4] qmp: Fix thread race To: Marc Morcos , Richard Henderson , Eduardo Habkost , "Dr . David Alan Gilbert" Cc: "Michael S . Tsirkin" , Marcel Apfelbaum , Markus Armbruster , Marcelo Tosatti , qemu-devel@nongnu.org, kvm@vger.kernel.org References: <20251213001443.2041258-1-marcmorcos@google.com> <20251213001443.2041258-4-marcmorcos@google.com> From: Paolo Bonzini Content-Language: en-US Autocrypt: addr=pbonzini@redhat.com; keydata= xsEhBFRCcBIBDqDGsz4K0zZun3jh+U6Z9wNGLKQ0kSFyjN38gMqU1SfP+TUNQepFHb/Gc0E2 CxXPkIBTvYY+ZPkoTh5xF9oS1jqI8iRLzouzF8yXs3QjQIZ2SfuCxSVwlV65jotcjD2FTN04 hVopm9llFijNZpVIOGUTqzM4U55sdsCcZUluWM6x4HSOdw5F5Utxfp1wOjD/v92Lrax0hjiX DResHSt48q+8FrZzY+AUbkUS+Jm34qjswdrgsC5uxeVcLkBgWLmov2kMaMROT0YmFY6A3m1S P/kXmHDXxhe23gKb3dgwxUTpENDBGcfEzrzilWueOeUWiOcWuFOed/C3SyijBx3Av/lbCsHU Vx6pMycNTdzU1BuAroB+Y3mNEuW56Yd44jlInzG2UOwt9XjjdKkJZ1g0P9dwptwLEgTEd3Fo UdhAQyRXGYO8oROiuh+RZ1lXp6AQ4ZjoyH8WLfTLf5g1EKCTc4C1sy1vQSdzIRu3rBIjAvnC tGZADei1IExLqB3uzXKzZ1BZ+Z8hnt2og9hb7H0y8diYfEk2w3R7wEr+Ehk5NQsT2MPI2QBd wEv1/Aj1DgUHZAHzG1QN9S8wNWQ6K9DqHZTBnI1hUlkp22zCSHK/6FwUCuYp1zcAEQEAAc0j UGFvbG8gQm9uemluaSA8cGJvbnppbmlAcmVkaGF0LmNvbT7CwU0EEwECACMFAlRCcBICGwMH CwkIBwMCAQYVCAIJCgsEFgIDAQIeAQIXgAAKCRB+FRAMzTZpsbceDp9IIN6BIA0Ol7MoB15E 11kRz/ewzryFY54tQlMnd4xxfH8MTQ/mm9I482YoSwPMdcWFAKnUX6Yo30tbLiNB8hzaHeRj jx12K+ptqYbg+cevgOtbLAlL9kNgLLcsGqC2829jBCUTVeMSZDrzS97ole/YEez2qFpPnTV0 VrRWClWVfYh+JfzpXmgyhbkuwUxNFk421s4Ajp3d8nPPFUGgBG5HOxzkAm7xb1cjAuJ+oi/K CHfkuN+fLZl/u3E/fw7vvOESApLU5o0icVXeakfSz0LsygEnekDbxPnE5af/9FEkXJD5EoYG SEahaEtgNrR4qsyxyAGYgZlS70vkSSYJ+iT2rrwEiDlo31MzRo6Ba2FfHBSJ7lcYdPT7bbk9 AO3hlNMhNdUhoQv7M5HsnqZ6unvSHOKmReNaS9egAGdRN0/GPDWr9wroyJ65ZNQsHl9nXBqE AukZNr5oJO5vxrYiAuuTSd6UI/xFkjtkzltG3mw5ao2bBpk/V/YuePrJsnPFHG7NhizrxttB nTuOSCMo45pfHQ+XYd5K1+Cv/NzZFNWscm5htJ0HznY+oOsZvHTyGz3v91pn51dkRYN0otqr bQ4tlFFuVjArBZcapSIe6NV8C4cEiSTOwE0EVEJx7gEIAMeHcVzuv2bp9HlWDp6+RkZe+vtl KwAHplb/WH59j2wyG8V6i33+6MlSSJMOFnYUCCL77bucx9uImI5nX24PIlqT+zasVEEVGSRF m8dgkcJDB7Tps0IkNrUi4yof3B3shR+vMY3i3Ip0e41zKx0CvlAhMOo6otaHmcxr35sWq1Jk tLkbn3wG+fPQCVudJJECvVQ//UAthSSEklA50QtD2sBkmQ14ZryEyTHQ+E42K3j2IUmOLriF dNr9NvE1QGmGyIcbw2NIVEBOK/GWxkS5+dmxM2iD4Jdaf2nSn3jlHjEXoPwpMs0KZsgdU0pP JQzMUMwmB1wM8JxovFlPYrhNT9MAEQEAAcLBMwQYAQIACQUCVEJx7gIbDAAKCRB+FRAMzTZp sadRDqCctLmYICZu4GSnie4lKXl+HqlLanpVMOoFNnWs9oRP47MbE2wv8OaYh5pNR9VVgyhD OG0AU7oidG36OeUlrFDTfnPYYSF/mPCxHttosyt8O5kabxnIPv2URuAxDByz+iVbL+RjKaGM GDph56ZTswlx75nZVtIukqzLAQ5fa8OALSGum0cFi4ptZUOhDNz1onz61klD6z3MODi0sBZN Aj6guB2L/+2ZwElZEeRBERRd/uommlYuToAXfNRdUwrwl9gRMiA0WSyTb190zneRRDfpSK5d usXnM/O+kr3Dm+Ui+UioPf6wgbn3T0o6I5BhVhs4h4hWmIW7iNhPjX1iybXfmb1gAFfjtHfL xRUr64svXpyfJMScIQtBAm0ihWPltXkyITA92ngCmPdHa6M1hMh4RDX+Jf1fiWubzp1voAg0 JBrdmNZSQDz0iKmSrx8xkoXYfA3bgtFN8WJH2xgFL28XnqY4M6dLhJwV3z08tPSRqYFm4NMP dRsn0/7oymhneL8RthIvjDDQ5ktUjMe8LtHr70OZE/TT88qvEdhiIVUogHdo4qBrk41+gGQh b906Dudw5YhTJFU3nC6bbF2nrLlB4C/XSiH76ZvqzV0Z/cAMBo5NF/w= In-Reply-To: <20251213001443.2041258-4-marcmorcos@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.129.124; envelope-from=pbonzini@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_H2=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=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: 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 On 12/13/25 01:14, Marc Morcos wrote: > @@ -346,7 +347,15 @@ static void monitor_qapi_event_emit(QAPIEvent event, QDict *qdict) > } > > qmp_mon = container_of(mon, MonitorQMP, common); > - if (qmp_mon->commands != &qmp_cap_negotiation_commands) { > + do_send = false; > + > + WITH_QEMU_LOCK_GUARD(&mon->mon_lock) { > + if (qmp_mon->commands != &qmp_cap_negotiation_commands) { > + do_send = true; > + } > + } > + > + if (do_send) { > qmp_send_response(qmp_mon, qdict); > } > } We cannot use WITH_QEMU_LOCK_GUARD with "continue" or "break" inside, but we can use QEMU_LOCK_GUARD: @@ -347,17 +346,13 @@ static void monitor_qapi_event_emit(QAPIEvent event, QDict *qdict) } qmp_mon = container_of(mon, MonitorQMP, common); - do_send = false; - - WITH_QEMU_LOCK_GUARD(&mon->mon_lock) { - if (qmp_mon->commands != &qmp_cap_negotiation_commands) { - do_send = true; + { + QEMU_LOCK_GUARD(&mon->mon_lock); + if (qmp_mon->commands == &qmp_cap_negotiation_commands) { + continue; } } - - if (do_send) { - qmp_send_response(qmp_mon, qdict); - } + qmp_send_response(qmp_mon, qdict); } } Let me know if this is okay for you! Paolo