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 DB1EA43F52; Tue, 30 Apr 2024 08:24:43 +0200 (CEST) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id A24CC402A8; Tue, 30 Apr 2024 08:24:43 +0200 (CEST) Received: from out30-131.freemail.mail.aliyun.com (out30-131.freemail.mail.aliyun.com [115.124.30.131]) by mails.dpdk.org (Postfix) with ESMTP id 2EB3740262 for ; Tue, 30 Apr 2024 05:46:08 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1714448767; h=Message-ID:Subject:Date:From:To; bh=XC+SFAprH1ZWRSqtogcDAC+ZpbhKBb7j6Uwl3GoX3Ps=; b=pbn1vFNOScUDqsamAWAQpIdFnhTyetqSfVedFh2l7bVITsO0w2LlDUDMMPov1qTumfmEBK/29R9u005KIu78MQjLUmbmz5AXsLeQkfbLKQIdUPH0Bg2KKdeqo6/rCpyRvH6+tDmkzdzRVptisfRKkNm6ipQsytGX6cA7Rl5uSdM= X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R151e4; CH=green; DM=||false|; DS=||; FP=0|-1|-1|-1|0|-1|-1|-1; HT=maildocker-contentspam033032014031; MF=xuanzhuo@linux.alibaba.com; NM=1; PH=DS; RN=8; SR=0; TI=SMTPD_---0W5b.6TA_1714448765; Received: from localhost(mailfrom:xuanzhuo@linux.alibaba.com fp:SMTPD_---0W5b.6TA_1714448765) by smtp.aliyun-inc.com; Tue, 30 Apr 2024 11:46:06 +0800 Message-ID: <1714448630.5571823-1-xuanzhuo@linux.alibaba.com> Subject: Re: [PATCH v3 1/2] vhost: destroy device when all vqs are inactive Date: Tue, 30 Apr 2024 11:43:50 +0800 From: Xuan Zhuo To: Stephen Hemminger Cc: Kangjie Xu , chenbo.xia@intel.com, dev@dpdk.org, hengqi@linux.alibaba.com, jasowang@redhat.com, mst@redhat.com, Maxime Coquelin References: <0383bb821dd65d8511a91e9f13b193230be59557.1662952732.git.kangjie.xu@linux.alibaba.com> <72b778f6-c813-4b20-1b9c-834d22191a5b@redhat.com> <20240429092742.3e717890@hermes.local> In-Reply-To: <20240429092742.3e717890@hermes.local> X-Mailman-Approved-At: Tue, 30 Apr 2024 08:24:42 +0200 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 Mon, 29 Apr 2024 09:27:42 -0700, Stephen Hemminger wrote: > On Tue, 11 Oct 2022 18:44:28 +0200 > Maxime Coquelin wrote: > > > On 9/12/22 05:36, Kangjie Xu wrote: > > > We change the behavior of vhost_user_get_vring_base(). Previosly, > > > destroying a virtqueue will cause the whole device to be destroyed. > > > The behavior is not specified in the vhost-user protocol. > > > > > > Thus, we refactor this part. The device will be destroyed only when > > > all virtqueues in the device are going to be destroyed. > > > > > > This helps us to simplify the implementation when resetting a virtqueue. > > > > > > Signed-off-by: Kangjie Xu > > > Signed-off-by: Xuan Zhuo > > > --- > > > lib/vhost/vhost_user.c | 10 ++++++++-- > > > 1 file changed, 8 insertions(+), 2 deletions(-) > > > > > > diff --git a/lib/vhost/vhost_user.c b/lib/vhost/vhost_user.c > > > index 4ad28bac45..a9f0709f94 100644 > > > --- a/lib/vhost/vhost_user.c > > > +++ b/lib/vhost/vhost_user.c > > > @@ -2088,10 +2088,16 @@ vhost_user_get_vring_base(struct virtio_net **pdev, > > > { > > > struct virtio_net *dev = *pdev; > > > struct vhost_virtqueue *vq = dev->virtqueue[ctx->msg.payload.state.index]; > > > + uint32_t i, num_live_vring = 0; > > > uint64_t val; > > > > > > - /* We have to stop the queue (virtio) if it is running. */ > > > - vhost_destroy_device_notify(dev); > > > + /* Stop the device when vq is the last active queue */ > > > + for (i = 0; i < dev->nr_vring; i++) > > > + if (dev->virtqueue[i]->access_ok) > > > + num_live_vring++; > > > + > > > + if (num_live_vring == 1 && vq->access_ok) > > > + vhost_destroy_device_notify(dev); > > > > > > dev->flags &= ~VIRTIO_DEV_READY; > > > dev->flags &= ~VIRTIO_DEV_VDPA_CONFIGURED; > > > > I think we are missing something here. > > > > We used to send the device destroy notification before getting the ring > > indexes, in order to ensure that the application has stopped processing > > the rings. > > > > With this patch, the application may still be polling the ring while we > > get the ring indexes (e.g. a thread in the application may be in the > > middle of rte_vhost_dequeue_burst() on that ring). So at best the ring > > indexes returned to the Vhost-user master will be outdated. At worst, it > > will crash the application because we call vring_invalidate() without > > the vq's lock being taken. > > > > I think you should protect all the VQ indexes fetching and VQ deinit > > using its access_lock. > > > > Maxime > > > > Please address Maxime's feedback. Kangjie has already resigned. Sorry, we don't have anyone in charge of this. If you need it, you can propose a new patch to solve this problem. Thanks.