From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 75276A0540; Fri, 8 Jul 2022 11:25:15 +0200 (CEST) Received: from [217.70.189.124] (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 6998640A83; Fri, 8 Jul 2022 11:25:15 +0200 (CEST) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by mails.dpdk.org (Postfix) with ESMTP id BF4B74021E for ; Fri, 8 Jul 2022 11:25:13 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1657272313; 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=wp4+azDkSU3VCaZYOFmuqw7jKVpLSRUHW3HV8E9K4dc=; b=AkoFsF9zNH4nQGtfxSokxKTIAI0J3lMpq7sAwvUtl1l1zSXRtTrguZqwth3au7r5uKfMD4 iPYh6361YjF1eDxqH4uTWVcUt04P/wLjN/reOmeHyTQoO9eq3vo5+iiFoOPzoqMl//agVs C+LC08lnlMn0x+tqXk4+RBNEddwPUHg= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-53-4eAn3kNwOcWNo2MJbLab2g-1; Fri, 08 Jul 2022 05:25:08 -0400 X-MC-Unique: 4eAn3kNwOcWNo2MJbLab2g-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id B10F785A588; Fri, 8 Jul 2022 09:25:07 +0000 (UTC) Received: from [10.39.208.8] (unknown [10.39.208.8]) by smtp.corp.redhat.com (Postfix) with ESMTPS id CC7AA492CA2; Fri, 8 Jul 2022 09:25:06 +0000 (UTC) Message-ID: <4fdc44d3-d9af-88ee-ebc1-7109cc69ce41@redhat.com> Date: Fri, 8 Jul 2022 11:25:05 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH] vdpa/sfc: resolve race between libvhost and dev_conf From: Maxime Coquelin To: abhimanyu.saini@xilinx.com, dev@dpdk.org Cc: chenbo.xia@intel.com, andrew.rybchenko@oktetlabs.ru, Abhimanyu Saini References: <20220706092401.36815-1-asaini@xilinx.com> In-Reply-To: X-Scanned-By: MIMEDefang 2.85 on 10.11.54.9 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=maxime.coquelin@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org On 7/8/22 11:23, Maxime Coquelin wrote: > > > On 7/6/22 11:24, abhimanyu.saini@xilinx.com wrote: >> From: Abhimanyu Saini >> >> libvhost calls dev_conf() before prosessing the >> VHOST_USER_SET_VRING_CALL message for the last VQ. So >> this message is processed after dev_conf() returns. >> >> However, the dev_conf() function spawns a thread to set >> rte_vhost_host_notifier_ctrl() before returning control to >> libvhost. This parallel thread in turn invokes get_notify_area(). >> To get the notify_area, the vdpa driver needs to query the HW and >> for this query it needs an enabled VQ. >> >> But at the same time libvhost is processing the last >> VHOST_USER_SET_VRING_CALL, and to do that it disables the last VQ. >> >> Hence there is a race b/w the libvhost and the vdpa driver. >> >> To resolve this race condition, query the HW and cache notify_area >> inside dev_conf() instead of doing it the parallel thread. >> >> Signed-off-by: Abhimanyu Saini >> --- >>   drivers/vdpa/sfc/sfc_vdpa_ops.c | 36 >> ++++++++++++++++++------------------ >>   drivers/vdpa/sfc/sfc_vdpa_ops.h |  1 + >>   2 files changed, 19 insertions(+), 18 deletions(-) >> > > Applied to dpdk-next-virtio/main. Sorry, I notice it is missing the Fixes tag, and cc'ing stable. Can you confirm this is needed and provide the faulty commit? Thanks, Maxime > Thanks, > Maxime