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=-2.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 400E5C433E0 for ; Fri, 15 Jan 2021 03:39:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0EABC23772 for ; Fri, 15 Jan 2021 03:39:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729096AbhAODjl (ORCPT ); Thu, 14 Jan 2021 22:39:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37498 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726311AbhAODjk (ORCPT ); Thu, 14 Jan 2021 22:39:40 -0500 Received: from mail-io1-xd30.google.com (mail-io1-xd30.google.com [IPv6:2607:f8b0:4864:20::d30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 88A30C061575 for ; Thu, 14 Jan 2021 19:39:00 -0800 (PST) Received: by mail-io1-xd30.google.com with SMTP id e22so15665926iom.5 for ; Thu, 14 Jan 2021 19:39:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=ToUJsMwDBuaHsW9Gv8sF8Wp8m3cG4OGDxZ84C52QhTg=; b=KvgZmNvYDisXkuSSUUTLi9XhFpXPFUBzQP94gBKHNsxjqdfyovIuBak325cfLGlxvM dLv/2FlC9zcz+iHNNJRsbvndDGctlkImuZpDLIbQ4GyzgumC9RUJXN9e1LQsumkG82tH xFiO5jcEqZEQbUKtJ6PQsAnpk6kuxqgyNgh4NILgYDi0bYlDoUWQaYRbAl0HEfLlBerT 0XXYVSarwv7hcGOsIse+4xEHFdeZiTQDC+tDzq05h8ElH3zsT+scOTm6k8MU3NQ1WYzD 1Ysuj4zeEL0EGRtXfzDfZGs5jkc9D7NVH2wbmCYi5IEpjqJAVz15elBmbewgptbI4VPW +wdQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=ToUJsMwDBuaHsW9Gv8sF8Wp8m3cG4OGDxZ84C52QhTg=; b=gbtgtM8l8kq/S8k5a6Dfaa8KlUgXxk40GVOkf23pugsvg+qeL/95If6Lb5QMC4MqIL C7+qqXtm1IAhq/sbtHwOlc4GswL2zcbpp9IyuXzO2F2f9NqFNQBP8QS5KGERuBl5iBq4 pU4tqTMx1g4dU59nGXBHTMqYGTsvp/oG5tiaIRXp30iyoKH3tJ/sCM6yL3FwQj4zh9Pd SKGO3BNkyADFprc9n1unq7UgIjr8YP9fZXrsxkieo8zmFiKFk39GW8lXIdggmZkIj040 BD5Epqazl6SpOZtpDh8g50r0jhErXt1xJkjp3NssIzEHYud3UuanMm3S+LnHbxG9GTlk 8zkA== X-Gm-Message-State: AOAM531cnYVZqhy92W6J2P7yL5ihI3b+vBmHdcDh0Cs9M+EF9gb6D/zU sod+4CUMXpDzWHcFhE2LRsXuk5wNK9vNiAVzXRg= X-Google-Smtp-Source: ABdhPJx/Bdwz7tTtP4cyJHfBEa/AYK5NdTPYk/LIz48SVXOhUT8T0ylHN1ynlFfwhE8DzIz+vfk5PgYKMCtLPeuAUl0= X-Received: by 2002:a92:d210:: with SMTP id y16mr9245356ily.97.1610681939931; Thu, 14 Jan 2021 19:38:59 -0800 (PST) MIME-Version: 1.0 References: <20210115003123.1254314-1-weiwan@google.com> <20210115003123.1254314-3-weiwan@google.com> In-Reply-To: From: Alexander Duyck Date: Thu, 14 Jan 2021 19:38:49 -0800 Message-ID: Subject: Re: [PATCH net-next v6 2/3] net: implement threaded-able napi poll loop support To: Wei Wang Cc: David Miller , Netdev , Jakub Kicinski , Eric Dumazet , Paolo Abeni , Hannes Frederic Sowa , Felix Fietkau Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, Jan 14, 2021 at 7:14 PM Alexander Duyck wrote: > > On Thu, Jan 14, 2021 at 4:33 PM Wei Wang wrote: > > > > +void napi_enable(struct napi_struct *n) > > +{ > > + BUG_ON(!test_bit(NAPI_STATE_SCHED, &n->state)); > > + smp_mb__before_atomic(); > > + clear_bit(NAPI_STATE_SCHED, &n->state); > > + clear_bit(NAPI_STATE_NPSVC, &n->state); > > + WARN_ON(napi_set_threaded(n, n->dev->threaded)); > > I am not sure what the point is in having a return value if you are > just using it to trigger a WARN_ON. It might make more sense to > actually set the WARN_ON inside of napi_set_threaded instead of having > it here as you could then identify the error much more easily. Or for > that matter you might be able to use something like pr_warn which > would allow you a more detailed message about the specific netdev that > experienced the failure. One additional change I would make here. The call to napi_set_threaded should be moved to before the smp_mb__before_atomic(). That way we can guarantee that the threaded flag and task_struct pointer are visible to all consumers before they can set NAPI_STATE_SCHED. Otherwise I think we run the risk of a race where a napi request could fire before we have finished configuring it.