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 X-Spam-Level: X-Spam-Status: No, score=-17.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 28D9BC433E6 for ; Tue, 2 Feb 2021 03:08:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C1AF864E91 for ; Tue, 2 Feb 2021 03:08:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230088AbhBBDId (ORCPT ); Mon, 1 Feb 2021 22:08:33 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:60985 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229819AbhBBDIc (ORCPT ); Mon, 1 Feb 2021 22:08:32 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612235224; 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=DYZ9+aRJ8bVLHVHjWPczPcqQ8T3GglKCO0MI3Vvvxx4=; b=JnD7jhx7KSrNzFll2giITjLkvHTtJJaH1INPlP5Sw/0YDoYmdFvzUyBQwrasTx9n/zEX2k l2l/GptlObfXh/LrwvQm/oRZfeE879ToUggAMhg7xo/3omSm9IeECv9bEz2XXInPCI/OLj n9lM5NU4flWrWCyiwMTbavsUyYKmE5A= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-561-AAfjKhMDO0mF1p6SU-u6-Q-1; Mon, 01 Feb 2021 22:07:01 -0500 X-MC-Unique: AAfjKhMDO0mF1p6SU-u6-Q-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id DEED659; Tue, 2 Feb 2021 03:06:59 +0000 (UTC) Received: from [10.72.13.250] (ovpn-13-250.pek2.redhat.com [10.72.13.250]) by smtp.corp.redhat.com (Postfix) with ESMTP id A1C6360BE5; Tue, 2 Feb 2021 03:06:57 +0000 (UTC) Subject: Re: [PATCH net] virtio-net: suppress bad irq warning for tx napi To: Wei Wang , David Miller , netdev@vger.kernel.org, Jakub Kicinski Cc: Willem de Bruijn , virtualization@lists.linux-foundation.org References: <20210129002136.70865-1-weiwan@google.com> From: Jason Wang Message-ID: Date: Tue, 2 Feb 2021 11:06:56 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210129002136.70865-1-weiwan@google.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 2021/1/29 上午8:21, Wei Wang wrote: > With the implementation of napi-tx in virtio driver, we clean tx > descriptors from rx napi handler, for the purpose of reducing tx > complete interrupts. But this could introduce a race where tx complete > interrupt has been raised, but the handler found there is no work to do > because we have done the work in the previous rx interrupt handler. > This could lead to the following warning msg: > [ 3588.010778] irq 38: nobody cared (try booting with the > "irqpoll" option) > [ 3588.017938] CPU: 4 PID: 0 Comm: swapper/4 Not tainted > 5.3.0-19-generic #20~18.04.2-Ubuntu > [ 3588.017940] Call Trace: > [ 3588.017942] > [ 3588.017951] dump_stack+0x63/0x85 > [ 3588.017953] __report_bad_irq+0x35/0xc0 > [ 3588.017955] note_interrupt+0x24b/0x2a0 > [ 3588.017956] handle_irq_event_percpu+0x54/0x80 > [ 3588.017957] handle_irq_event+0x3b/0x60 > [ 3588.017958] handle_edge_irq+0x83/0x1a0 > [ 3588.017961] handle_irq+0x20/0x30 > [ 3588.017964] do_IRQ+0x50/0xe0 > [ 3588.017966] common_interrupt+0xf/0xf > [ 3588.017966] > [ 3588.017989] handlers: > [ 3588.020374] [<000000001b9f1da8>] vring_interrupt > [ 3588.025099] Disabling IRQ #38 > > This patch adds a new param to struct vring_virtqueue, and we set it for > tx virtqueues if napi-tx is enabled, to suppress the warning in such > case. > > Fixes: 7b0411ef4aa6 ("virtio-net: clean tx descriptors from rx napi") > Reported-by: Rick Jones > Signed-off-by: Wei Wang > Signed-off-by: Willem de Bruijn Please use get_maintainer.pl to make sure Michael and me were cced. > --- > drivers/net/virtio_net.c | 19 ++++++++++++++----- > drivers/virtio/virtio_ring.c | 16 ++++++++++++++++ > include/linux/virtio.h | 2 ++ > 3 files changed, 32 insertions(+), 5 deletions(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index 508408fbe78f..e9a3f30864e8 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -1303,13 +1303,22 @@ static void virtnet_napi_tx_enable(struct virtnet_info *vi, > return; > } > > + /* With napi_tx enabled, free_old_xmit_skbs() could be called from > + * rx napi handler. Set work_steal to suppress bad irq warning for > + * IRQ_NONE case from tx complete interrupt handler. > + */ > + virtqueue_set_work_steal(vq, true); > + > return virtnet_napi_enable(vq, napi); Do we need to force the ordering between steal set and napi enable? > } > > -static void virtnet_napi_tx_disable(struct napi_struct *napi) > +static void virtnet_napi_tx_disable(struct virtqueue *vq, > + struct napi_struct *napi) > { > - if (napi->weight) > + if (napi->weight) { > napi_disable(napi); > + virtqueue_set_work_steal(vq, false); > + } > } > > static void refill_work(struct work_struct *work) > @@ -1835,7 +1844,7 @@ static int virtnet_close(struct net_device *dev) > for (i = 0; i < vi->max_queue_pairs; i++) { > xdp_rxq_info_unreg(&vi->rq[i].xdp_rxq); > napi_disable(&vi->rq[i].napi); > - virtnet_napi_tx_disable(&vi->sq[i].napi); > + virtnet_napi_tx_disable(vi->sq[i].vq, &vi->sq[i].napi); > } > > return 0; > @@ -2315,7 +2324,7 @@ static void virtnet_freeze_down(struct virtio_device *vdev) > if (netif_running(vi->dev)) { > for (i = 0; i < vi->max_queue_pairs; i++) { > napi_disable(&vi->rq[i].napi); > - virtnet_napi_tx_disable(&vi->sq[i].napi); > + virtnet_napi_tx_disable(vi->sq[i].vq, &vi->sq[i].napi); > } > } > } > @@ -2440,7 +2449,7 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog, > if (netif_running(dev)) { > for (i = 0; i < vi->max_queue_pairs; i++) { > napi_disable(&vi->rq[i].napi); > - virtnet_napi_tx_disable(&vi->sq[i].napi); > + virtnet_napi_tx_disable(vi->sq[i].vq, &vi->sq[i].napi); > } > } > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index 71e16b53e9c1..f7c5d697c302 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -105,6 +105,9 @@ struct vring_virtqueue { > /* Host publishes avail event idx */ > bool event; > > + /* Tx side napi work could be done from rx side. */ > + bool work_steal; So vring_vritqueue is a general structure, let's avoid mentioning network specific stuffs here. And we need a better name like "no_interrupt_check"? And we need a separate patch for virtio core changes. > + > /* Head of free buffer list. */ > unsigned int free_head; > /* Number we've added since last sync. */ > @@ -1604,6 +1607,7 @@ static struct virtqueue *vring_create_virtqueue_packed( > vq->notify = notify; > vq->weak_barriers = weak_barriers; > vq->broken = false; > + vq->work_steal = false; > vq->last_used_idx = 0; > vq->num_added = 0; > vq->packed_ring = true; > @@ -2038,6 +2042,9 @@ irqreturn_t vring_interrupt(int irq, void *_vq) > > if (!more_used(vq)) { > pr_debug("virtqueue interrupt with no work for %p\n", vq); Do we still need to keep this warning? > + if (vq->work_steal) > + return IRQ_HANDLED; So I wonder instead of doing trick like this, maybe it's time to unify TX/RX NAPI with the help of[1] (virtio-net use queue pairs). Thanks [1] https://lkml.org/lkml/2014/12/25/169 > + > return IRQ_NONE; > } > > @@ -2082,6 +2089,7 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index, > vq->notify = notify; > vq->weak_barriers = weak_barriers; > vq->broken = false; > + vq->work_steal = false; > vq->last_used_idx = 0; > vq->num_added = 0; > vq->use_dma_api = vring_use_dma_api(vdev); > @@ -2266,6 +2274,14 @@ bool virtqueue_is_broken(struct virtqueue *_vq) > } > EXPORT_SYMBOL_GPL(virtqueue_is_broken); > > +void virtqueue_set_work_steal(struct virtqueue *_vq, bool val) > +{ > + struct vring_virtqueue *vq = to_vvq(_vq); > + > + vq->work_steal = val; > +} > +EXPORT_SYMBOL_GPL(virtqueue_set_work_steal); > + > /* > * This should prevent the device from being used, allowing drivers to > * recover. You may need to grab appropriate locks to flush. > diff --git a/include/linux/virtio.h b/include/linux/virtio.h > index 55ea329fe72a..091c30f21ff9 100644 > --- a/include/linux/virtio.h > +++ b/include/linux/virtio.h > @@ -84,6 +84,8 @@ unsigned int virtqueue_get_vring_size(struct virtqueue *vq); > > bool virtqueue_is_broken(struct virtqueue *vq); > > +void virtqueue_set_work_steal(struct virtqueue *vq, bool val); > + > const struct vring *virtqueue_get_vring(struct virtqueue *vq); > dma_addr_t virtqueue_get_desc_addr(struct virtqueue *vq); > dma_addr_t virtqueue_get_avail_addr(struct virtqueue *vq);