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=-5.1 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, URIBL_BLOCKED,USER_AGENT_SANE_1 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 DA8E1C433E7 for ; Sat, 17 Oct 2020 13:51:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 869452072D for ; Sat, 17 Oct 2020 13:51:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="YD6Xq6L9" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2438197AbgJQNqH (ORCPT ); Sat, 17 Oct 2020 09:46:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43616 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2438192AbgJQNqG (ORCPT ); Sat, 17 Oct 2020 09:46:06 -0400 Received: from mail-ej1-x62b.google.com (mail-ej1-x62b.google.com [IPv6:2a00:1450:4864:20::62b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8544DC061755 for ; Sat, 17 Oct 2020 06:46:06 -0700 (PDT) Received: by mail-ej1-x62b.google.com with SMTP id h24so7501835ejg.9 for ; Sat, 17 Oct 2020 06:46:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=to:cc:from:subject:message-id:date:user-agent:mime-version :content-language:content-transfer-encoding; bh=FPhEdIY5KuEMvseRGzglc0TnMkq8eN0fVBxf9t9vD5g=; b=YD6Xq6L9uo2dCF0d4GH1W7AaYY8jASnSXy0nNWzGn+xqSOiVK1aehGqWgRjOko4hnX ngt15q+s9eO11qmRpKM4EdnkmiVq9qdpvlCx2y5AbaPKaqow/EQmnvMTMVv3HhjGD6t8 Hvp4yvJdEp++vYijW9YJxU63425J3IWzRfEhJWXFPxfQNU+iowpfFlKhTDbnEDzuYiJl UioP4xsHAwk0Cuwk7Ag4srSq5GjImFoL30FHtDrNmDlR+zNWLYaxARQ2R9qvX1nl6Gz/ WJjbi7ka5BRjt/+b/HOpIQkD8P2ZpmkWUv1VOveatgm4kZBsfsjV0uskoNmkwaSZHbMP RQOw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:to:cc:from:subject:message-id:date:user-agent :mime-version:content-language:content-transfer-encoding; bh=FPhEdIY5KuEMvseRGzglc0TnMkq8eN0fVBxf9t9vD5g=; b=gcX+FvRgh6fxI9BxwatDfNLHwChH1UucAY8rd8qpaQ24Yk/6ioS76aTtVoS67ilOj0 yJXaqreuslH78Oz+FaO4myngv5KYmcfC0NKhe3/eP0eQT9rtY8I5FrdEOG1dsCw8r0SO H1DGE7hFQisZ+WtfwlY6UcjFDn3nAEjS6snRcCT6lS+opeQ6aOgWFKWCpakokCkwWMy/ N2rtoRbyUbgiXOgjbrgDpi+EdgVIzb++zUPIyXXWXQ7dPKHGfpMvu8GqdvoahGh5hHCU ZwKlrgs2Il4AjqtyGH9s3gsON5ldug+GR6EO3AAa6r30+gJtF3rfV3jTPTriymK3Rvx2 1fvg== X-Gm-Message-State: AOAM530fTzWP77Q84G8/x8a8MEbr/3iWw2vvdMjVsRrudaPb5K0pscwm IiHai4XTxuKFbNSDqyirRP1XNk0Z3bM= X-Google-Smtp-Source: ABdhPJw5gVweXS2zgH29uDh4ZR0xTYv7IACRS4dRVBO/Wcqh+FJJRv+YJCjooJPAS4RemrcmylBf4A== X-Received: by 2002:a17:907:104f:: with SMTP id oy15mr8833258ejb.261.1602942364902; Sat, 17 Oct 2020 06:46:04 -0700 (PDT) Received: from ?IPv6:2003:ea:8f23:2800:f845:b1c9:b817:f8d3? (p200300ea8f232800f845b1c9b817f8d3.dip0.t-ipconnect.de. [2003:ea:8f23:2800:f845:b1c9:b817:f8d3]) by smtp.googlemail.com with ESMTPSA id i5sm5052996ejv.54.2020.10.17.06.46.04 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 17 Oct 2020 06:46:04 -0700 (PDT) To: Eric Dumazet , Eric Dumazet , David Miller , Jakub Kicinski Cc: "netdev@vger.kernel.org" From: Heiner Kallweit Subject: Remove __napi_schedule_irqoff? Message-ID: <01af7f4f-bd05-b93e-57ad-c2e9b8726e90@gmail.com> Date: Sat, 17 Oct 2020 15:45:57 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.12.1 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org When __napi_schedule_irqoff was added with bc9ad166e38a ("net: introduce napi_schedule_irqoff()") the commit message stated: "Many NIC drivers can use it from their hard IRQ handler instead of generic variant." It turned out that this most of the time isn't safe in certain configurations: - if CONFIG_PREEMPT_RT is set - if command line parameter threadirqs is set Having said that drivers are being switched back to __napi_schedule(), see e.g. patch in [0] and related discussion. I thought about a __napi_schedule version checking dynamically whether interrupts are disabled. But checking e.g. variable force_irqthreads also comes at a cost, so that we may not see a benefit compared to calling local_irq_save/local_irq_restore. If more or less all users have to switch back, then the question is whether we should remove __napi_schedule_irqoff. Instead of touching all users we could make __napi_schedule_irqoff an alias for __napi_schedule for now. [0] https://lkml.org/lkml/2020/10/8/706