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=-16.1 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,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 57DC0C433E0 for ; Tue, 2 Feb 2021 23:13:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EF0E9601FB for ; Tue, 2 Feb 2021 23:13:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236305AbhBBXNa (ORCPT ); Tue, 2 Feb 2021 18:13:30 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:58838 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236183AbhBBXN2 (ORCPT ); Tue, 2 Feb 2021 18:13:28 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612307520; 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: in-reply-to:in-reply-to:references:references; bh=p990RZMi8C61rNselXGUhwIY4CsNl6vMdGACytrGF44=; b=IxxOvpDvWKHf52hs2fWvV15gMWpcGgsYtKsOoMDQAv5tYcb2Pd7tXMiB9zTGSCgE0lVnyd bKZXbsmyKlloVOYphCTRBIBeZdInRlY3z50NBX1P2kMAiSpqXK4DKref0mclBakORUwRJ+ pXTkY68HNpzUnZsV+FBTsCCs8Z1ww0w= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-532-DCXHAo0kO3etvf7jBQI4rg-1; Tue, 02 Feb 2021 18:11:58 -0500 X-MC-Unique: DCXHAo0kO3etvf7jBQI4rg-1 Received: by mail-wm1-f69.google.com with SMTP id q24so2172816wmc.1 for ; Tue, 02 Feb 2021 15:11:58 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=p990RZMi8C61rNselXGUhwIY4CsNl6vMdGACytrGF44=; b=hKpH0yDMxE6699NkmqIlwNt/vQGSM9huHQtxPkR6UiO7ArDblOSy8hWMCyJg/ST5+e E3UcCdr6E0XjbxUTR5g35oh5MsVur27M2T5pmyhvnl38T77AoIQpjJY2/wzySZwkE06U 0pgrKZGuGNBCYBTBAc58cc/mmC51c+6ajFY160Tday4nIKlj7/PrFlKsnbPArFD32IoV /nZPV2OeeBQJkYNniQfgOYvPO9FGZZ9zz/kMsrGoWI1vhaDnq80tUGW4ESLbZ3pP7CmP 4P2xnxfYXMvpULAgY0SmF/hB8rkKRgPB0a6mv2B08HeWUdAxFYzkpyBzodmtSiOJ90+l qyfA== X-Gm-Message-State: AOAM5304oI7qd3JY0H/z2Ao34LY7xh1WQNA1g+PRpuCTiGpnyxper9x0 ub58IqrQcKktYt9fIPibC7wBk1Scah1T8Cjt8JKMmAhEMlvi8wG9VwGO+nsyW8afdRwbvP1Vxnf 2+/lmH7EuhDmhJ+uQ X-Received: by 2002:a1c:6602:: with SMTP id a2mr272111wmc.74.1612307517586; Tue, 02 Feb 2021 15:11:57 -0800 (PST) X-Google-Smtp-Source: ABdhPJz5PAplDAsbPdIMbTXF8udNdAvRTiXJ/fkDLcpjYpRjHB4MQwPRwuGC1G/4OqNgJfEKU8YTzw== X-Received: by 2002:a1c:6602:: with SMTP id a2mr272088wmc.74.1612307517225; Tue, 02 Feb 2021 15:11:57 -0800 (PST) Received: from redhat.com (bzq-79-177-39-148.red.bezeqint.net. [79.177.39.148]) by smtp.gmail.com with ESMTPSA id n15sm212671wrx.2.2021.02.02.15.11.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Feb 2021 15:11:56 -0800 (PST) Date: Tue, 2 Feb 2021 18:11:54 -0500 From: "Michael S. Tsirkin" To: Wei Wang Cc: David Miller , netdev@vger.kernel.org, Jakub Kicinski , Willem de Bruijn , virtualization@lists.linux-foundation.org Subject: Re: [PATCH net] virtio-net: suppress bad irq warning for tx napi Message-ID: <20210202180807-mutt-send-email-mst@kernel.org> References: <20210129002136.70865-1-weiwan@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210129002136.70865-1-weiwan@google.com> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, Jan 28, 2021 at 04:21:36PM -0800, 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 This description does not make sense to me. irq X: nobody cared only triggers after an interrupt is unhandled repeatedly. So something causes a storm of useless tx interrupts here. Let's find out what it was please. What you are doing is just preventing linux from complaining. > --- > 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); > } > > -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; > + > /* 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); > + if (vq->work_steal) > + return IRQ_HANDLED; > + > 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); > -- > 2.30.0.365.g02bc693789-goog >