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=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 BEA13C8B4C6 for ; Mon, 16 Nov 2020 12:42:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5885120E65 for ; Mon, 16 Nov 2020 12:42:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="OgrOPH8I" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727422AbgKPMmv (ORCPT ); Mon, 16 Nov 2020 07:42:51 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:21610 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726598AbgKPMmv (ORCPT ); Mon, 16 Nov 2020 07:42:51 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1605530569; 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=ebTze6DX+bt9ao6H/89yHeOnEFANqz0oC2+q+FvQf/4=; b=OgrOPH8IOs4DWTuyxIbebon/7SAT9rUfoqLuOtgj5dXNezjBB1Ch+1LN+2IrxLZu3lLb+m USCBr/VCaMirS117CLyAGXzvtZFwVkvcfZu5QOiUZJPpiYTqQocKVKzjy76+aISjVFRC/1 W5rKZ3yszADd/nknW/d+Oq3FYGo9LQE= Received: from mail-wr1-f71.google.com (mail-wr1-f71.google.com [209.85.221.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-7-S_wHj3GDM1mxp4ui5L5nFA-1; Mon, 16 Nov 2020 07:42:47 -0500 X-MC-Unique: S_wHj3GDM1mxp4ui5L5nFA-1 Received: by mail-wr1-f71.google.com with SMTP id z7so9831696wrl.14 for ; Mon, 16 Nov 2020 04:42:47 -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:content-transfer-encoding :in-reply-to; bh=ebTze6DX+bt9ao6H/89yHeOnEFANqz0oC2+q+FvQf/4=; b=WiLgMjy7CMBH1IxQPR64+n8DnbnBY9cX1YMImW4og0/MDv+BydqdA5fSL0XOgcGwTj PV34yWM3dKZluJG8ppstIm6ZZQosnRyenzSD4FV8Mlu7JBvzbQZ3HIEple++lONUhx9n qOIYzyFgrpA+ONrQOj/P0tE6DYySIxRZUllNW7g6UeD+rLKhKrq6KfTXeiiwnCPaDM5B 6VaOPSTzjaYIz2e04cnGOXkyNeRS70WFHQpKduqrkgiBvcc3ztf86fysyHPP4RUxvA6f XONbh+UFtC+gyACuUDNcmJR5jIDkm3jWslbSZflAX5ZzhFrTqL2AJxI0BMpvJXS5etfd tSUQ== X-Gm-Message-State: AOAM532fgLdMEKPrsJ7AQuAa5Qxb/7GMvjnl6fR7CVe1QEsRiz0YLRT2 foHipH86XhbJPLJfyxtBdz6c+UHU7/jWGDzfZ0GYWiBprF2C6cJDeQTFR9N+B3Z9Bypt4BLHApy +/MeZ1d3N0lvv2SZX X-Received: by 2002:adf:cd8d:: with SMTP id q13mr19546280wrj.61.1605530566741; Mon, 16 Nov 2020 04:42:46 -0800 (PST) X-Google-Smtp-Source: ABdhPJzvLNvqw2PCiGnQ/AnYIf9wyKk6yla1iwqBK5/HgTes54MIdQk05hIzkeOYR0tQ+cjEhCV+5Q== X-Received: by 2002:adf:cd8d:: with SMTP id q13mr19546248wrj.61.1605530566524; Mon, 16 Nov 2020 04:42:46 -0800 (PST) Received: from redhat.com ([147.161.8.56]) by smtp.gmail.com with ESMTPSA id w21sm19377559wmi.29.2020.11.16.04.42.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 Nov 2020 04:42:45 -0800 (PST) Date: Mon, 16 Nov 2020 07:42:34 -0500 From: "Michael S. Tsirkin" To: =?iso-8859-1?Q?Bj=F6rn_T=F6pel?= Cc: =?iso-8859-1?Q?Bj=F6rn_T=F6pel?= , netdev@vger.kernel.org, bpf@vger.kernel.org, magnus.karlsson@intel.com, ast@kernel.org, daniel@iogearbox.net, maciej.fijalkowski@intel.com, sridhar.samudrala@intel.com, jesse.brandeburg@intel.com, qi.z.zhang@intel.com, kuba@kernel.org, edumazet@google.com, jonathan.lemon@gmail.com, maximmi@nvidia.com, intel-wired-lan@lists.osuosl.org, netanel@amazon.com, akiyano@amazon.com, michael.chan@broadcom.com, sgoutham@marvell.com, ioana.ciornei@nxp.com, ruxandra.radulescu@nxp.com, thomas.petazzoni@bootlin.com, mcroce@microsoft.com, saeedm@nvidia.com, tariqt@nvidia.com, aelior@marvell.com, ecree@solarflare.com, ilias.apalodimas@linaro.org, grygorii.strashko@ti.com, sthemmin@microsoft.com, kda@linux-powerpc.org Subject: Re: [PATCH bpf-next v2 06/10] xsk: propagate napi_id to XDP socket Rx path Message-ID: <20201116073848-mutt-send-email-mst@kernel.org> References: <20201116110416.10719-1-bjorn.topel@gmail.com> <20201116110416.10719-7-bjorn.topel@gmail.com> <20201116064953-mutt-send-email-mst@kernel.org> <614a7ce4-2b6b-129b-de7d-71428f7a71f6@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <614a7ce4-2b6b-129b-de7d-71428f7a71f6@intel.com> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, Nov 16, 2020 at 01:01:40PM +0100, Björn Töpel wrote: > > On 2020-11-16 12:55, Michael S. Tsirkin wrote: > > On Mon, Nov 16, 2020 at 12:04:12PM +0100, Björn Töpel wrote: > > > From: Björn Töpel > > > > > > Add napi_id to the xdp_rxq_info structure, and make sure the XDP > > > socket pick up the napi_id in the Rx path. The napi_id is used to find > > > the corresponding NAPI structure for socket busy polling. > > > > > > Acked-by: Ilias Apalodimas > > > Signed-off-by: Björn Töpel > > > > A bunch of drivers just pass in 0. could you explain when > > is that ok? how bad is it if the wrong id is used? > > > > If zero is passed, which is a non-valid NAPI_ID, busy-polling will never > be performed. > > Depending on the structure of the driver, napi might or might not be > initialized (napi_id != 0) or even available. When it wasn't obvious, I > simply set it to zero. > > So, short; No harm if zero, but busy-polling cannot be used in an XDP > context. > > > [...] > > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > > > index 21b71148c532..d71fe41595b7 100644 > > > --- a/drivers/net/virtio_net.c > > > +++ b/drivers/net/virtio_net.c > > > @@ -1485,7 +1485,7 @@ static int virtnet_open(struct net_device *dev) > > > if (!try_fill_recv(vi, &vi->rq[i], GFP_KERNEL)) > > > schedule_delayed_work(&vi->refill, 0); > > > - err = xdp_rxq_info_reg(&vi->rq[i].xdp_rxq, dev, i); > > > + err = xdp_rxq_info_reg(&vi->rq[i].xdp_rxq, dev, i, 0); > > > if (err < 0) > > > return err; > > > > Should this be rq.napi.napi_id ? > > > > Yes, if rq.napi.napi_id is valid here! Is it? What initializes it? netif_napi_add? Then I think yes, it's initialized for all queues ... Needs to be tested naturally. > > Cheers, > Björn