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=-18.0 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 4EA42C433DB for ; Thu, 4 Feb 2021 03:07:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 12FCF64F4D for ; Thu, 4 Feb 2021 03:07:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234486AbhBDDHn (ORCPT ); Wed, 3 Feb 2021 22:07:43 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:55593 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234232AbhBDDHj (ORCPT ); Wed, 3 Feb 2021 22:07:39 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612407972; 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=VP2C7mfebrEmwVn94wtq4kLWLgP8Sp1nVsZO1XYRiLY=; b=ARacZeKDmfvodtY0LaS29Y7mR6inJEjrgjg/Pr29Ry4i26bdN/3d5M1mVlRaIEdtsYzts2 9C2dN6hacdWBmQjTWfUA7ikPql9kqYK6oFM/+/idY/TXH7AzfMRtHT1u8D6nnfZmWKNRcp s+8CJFPNUkmV1torcNSio8bh/IwtBQs= 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-71-te9GeJ2CMHCLm2hLyOpPNw-1; Wed, 03 Feb 2021 22:06:07 -0500 X-MC-Unique: te9GeJ2CMHCLm2hLyOpPNw-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 5EB34107ACE6; Thu, 4 Feb 2021 03:06:06 +0000 (UTC) Received: from [10.72.14.1] (ovpn-14-1.pek2.redhat.com [10.72.14.1]) by smtp.corp.redhat.com (Postfix) with ESMTP id D0E946091B; Thu, 4 Feb 2021 03:06:03 +0000 (UTC) Subject: Re: [PATCH net] virtio-net: suppress bad irq warning for tx napi To: Willem de Bruijn Cc: Wei Wang , David Miller , Network Development , Jakub Kicinski , Willem de Bruijn , virtualization@lists.linux-foundation.org References: <20210129002136.70865-1-weiwan@google.com> <3a3e005d-f9b2-c16a-5ada-6e04242c618e@redhat.com> From: Jason Wang Message-ID: <9b0b8f2a-8476-697e-9002-e9947e3eab63@redhat.com> Date: Thu, 4 Feb 2021 11:06:02 +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: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 2021/2/4 上午2:28, Willem de Bruijn wrote: > On Wed, Feb 3, 2021 at 12:33 AM Jason Wang wrote: >> >> On 2021/2/2 下午10:37, Willem de Bruijn wrote: >>> On Mon, Feb 1, 2021 at 10:09 PM Jason Wang wrote: >>>> 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. >>> Will do. Sorry about that. I suggested just the virtualization list, my bad. >>> >>>>> --- >>>>> 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? >>> The warning only occurs after one hundred spurious interrupts, so not >>> really. >> >> Ok, so it looks like a hint. Then I wonder how much value do we need to >> introduce helper like virtqueue_set_work_steal() that allows the caller >> to toggle. How about disable the check forever during virtqueue >> initialization? > Yes, that is even simpler. > > We still need the helper, as the internal variables of vring_virtqueue > are not accessible from virtio-net. An earlier patch added the > variable to virtqueue itself, but I think it belongs in > vring_virtqueue. And the helper is not a lot of code. It's better to do this before the allocating the irq. But it looks not easy unless we extend find_vqs(). Thanks >