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 2B292A00C3; Tue, 20 Sep 2022 09:19:22 +0200 (CEST) Received: from [217.70.189.124] (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id C519440DFB; Tue, 20 Sep 2022 09:19:21 +0200 (CEST) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by mails.dpdk.org (Postfix) with ESMTP id E7BAE4069B for ; Tue, 20 Sep 2022 09:19:19 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1663658359; 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=t2muB0MazITSDh5x41gCSrxOTVO6kFyiOg1bVRx5Xaw=; b=Eod16y9WMLW9FsztJkvK7gMlmF/iOV97JLkPk98sNcyZ27GJ20P9FWNeW02L+J+DVBbu/k RJCoHHosejHS/OpyKeicxple0jkZsKAKNLj3i0aUViRzP8uLoae+kMTTCtCsdzEEjS1DS+ aqrocNqhOU6vcMMySxZ4L60gxIk0GmI= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-138-oxgU1MbWMTKmkQCzhprugA-1; Tue, 20 Sep 2022 03:19:18 -0400 X-MC-Unique: oxgU1MbWMTKmkQCzhprugA-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 DAEFD29ABA3A; Tue, 20 Sep 2022 07:19:17 +0000 (UTC) Received: from [10.39.208.16] (unknown [10.39.208.16]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2A9CB492CA2; Tue, 20 Sep 2022 07:19:17 +0000 (UTC) Message-ID: <2a63f996-84f4-434f-1b19-5dd035870e9d@redhat.com> Date: Tue, 20 Sep 2022 09:19:15 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.2.0 Subject: Re: [PATCH] vhost: use try_lock in rte_vhost_vring_call To: Changpeng Liu , dev@dpdk.org Cc: Chenbo Xia References: <20220906022225.17215-1-changpeng.liu@intel.com> From: Maxime Coquelin In-Reply-To: <20220906022225.17215-1-changpeng.liu@intel.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 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: 7bit 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 9/6/22 04:22, Changpeng Liu wrote: > Note that this function is in data path, so the thread context > may not same as socket messages processing context, by using > try_lock here, users can have another try in case of VQ's access > lock is held by `vhost-events` thread. > > Signed-off-by: Changpeng Liu > --- > lib/vhost/vhost.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/lib/vhost/vhost.c b/lib/vhost/vhost.c > index 60cb05a0ff..072d2acb7b 100644 > --- a/lib/vhost/vhost.c > +++ b/lib/vhost/vhost.c > @@ -1329,7 +1329,11 @@ rte_vhost_vring_call(int vid, uint16_t vring_idx) > if (!vq) > return -1; > > - rte_spinlock_lock(&vq->access_lock); > + if (!rte_spinlock_trylock(&vq->access_lock)) { > + VHOST_LOG_CONFIG(dev->ifname, DEBUG, > + "failed to kick guest, virtqueue busy.\n"); > + return -1; > + } > > if (vq_is_packed(dev)) > vhost_vring_call_packed(dev, vq); I think that's problematic, because it will break other applications that currently rely on the API to block until the call is done. Just some internal DPDK usage of this API: ./drivers/vdpa/ifc/ifcvf_vdpa.c:871: rte_vhost_vring_call(internal->vid, qid); ./examples/vhost/virtio_net.c:236: rte_vhost_vring_call(dev->vid, queue_id); ./examples/vhost/virtio_net.c:446: rte_vhost_vring_call(dev->vid, queue_id); ./examples/vhost_blk/vhost_blk.c:99: rte_vhost_vring_call(task->ctrlr->vid, vq->id); ./examples/vhost_blk/vhost_blk.c:134: rte_vhost_vring_call(task->ctrlr->vid, vq->id); This change will break all the above uses. And that's not counting external projects. ou should better introduce a new API that does not block. Regards, Maxime