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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 97B75C3279D for ; Sat, 10 Oct 2020 23:09:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5EC882075E for ; Sat, 10 Oct 2020 23:09:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602371377; bh=qcgYt92nQkQECI+HSkkYIfU5hZxl0DXeMxKwadsTjS4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=N0Ixvs5mzvMJRjgEqF20AW2z/h/pkclLVEC9sEJv5BYeJ5MTnSDPmygHzOKCmj52j n0Q5ExMcw/DQLXA8NNq1q+K9r1plAk1PDQQlzJNK3tRD9KwRhg9VxJK4R0+4l2rhMK CRkPizOwu6iSwbjK88s0ItndJWlNGHI9nrUXRI1Q= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390195AbgJJW4r (ORCPT ); Sat, 10 Oct 2020 18:56:47 -0400 Received: from mail.kernel.org ([198.145.29.99]:53930 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731823AbgJJTh1 (ORCPT ); Sat, 10 Oct 2020 15:37:27 -0400 Received: from kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com (unknown [163.114.132.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C760522314; Sat, 10 Oct 2020 15:22:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602343370; bh=qcgYt92nQkQECI+HSkkYIfU5hZxl0DXeMxKwadsTjS4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=P2znDrM/eqI7D3XAYTGy+DDuXoYOsarn/0w5SeAeyGMDJuOc3oJ5A9w8cZQR809Wm ZVn8r62q0eG1jkIdrYAmzpw98cz3ABmuA8euZAR8Wl2RUzIRmtN1cLYKpa2eY1s887 dgtgpnjl+iQrP2ufB5ThOwYF7vKbV0N7T7a6G/Ik= Date: Sat, 10 Oct 2020 08:22:48 -0700 From: Jakub Kicinski To: Heiner Kallweit Cc: John Keeping , netdev@vger.kernel.org, Giuseppe Cavallaro , Alexandre Torgue , Jose Abreu , "David S. Miller" , Maxime Coquelin , linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Eric Dumazet Subject: Re: [PATCH] net: stmmac: Don't call _irqoff() with hardirqs enabled Message-ID: <20201010082248.22cc7656@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> In-Reply-To: <070b2b87-f38c-088d-4aaf-12045dbd92f7@gmail.com> References: <20201008162749.860521-1-john@metanate.com> <8036d473-68bd-7ee7-e2e9-677ff4060bd3@gmail.com> <20201009085805.65f9877a@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> <725ba7ca-0818-074b-c380-15abaa5d037b@gmail.com> <070b2b87-f38c-088d-4aaf-12045dbd92f7@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 10 Oct 2020 15:08:15 +0200 Heiner Kallweit wrote: > On 09.10.2020 18:06, Heiner Kallweit wrote: > > On 09.10.2020 17:58, Jakub Kicinski wrote: > >> On Fri, 9 Oct 2020 16:54:06 +0200 Heiner Kallweit wrote: > >>> I'm thinking about a __napi_schedule version that disables hard irq's > >>> conditionally, based on variable force_irqthreads, exported by the irq > >>> subsystem. This would allow to behave correctly with threadirqs set, > >>> whilst not loosing the _irqoff benefit with threadirqs unset. > >>> Let me come up with a proposal. > >> > >> I think you'd need to make napi_schedule_irqoff() behave like that, > >> right? Are there any uses of napi_schedule_irqoff() that are disabling > >> irqs and not just running from an irq handler? > >> > > Right, the best approach depends on the answer to the latter question. > > I didn't check this yet, therefore I described the least intrusive approach. > > > > With some help from coccinelle I identified the following functions that > call napi_schedule_irqoff() or __napi_schedule_irqoff() and do not run > from an irq handler (at least not at the first glance). > > dpaa2_caam_fqdan_cb > qede_simd_fp_handler > mlx4_en_rx_irq > mlx4_en_tx_irq Don't know the others but FWIW the mlx4 ones run from an IRQ handler, AFAICT: static irqreturn_t mlx4_interrupt(int irq, void *dev_ptr) static irqreturn_t mlx4_msi_x_interrupt(int irq, void *eq_ptr) mlx4_eq_int() mlx4_cq_completion cq->comp() > qeth_qdio_poll > netvsc_channel_cb > napi_watchdog This one runs from a hrtimer, which I believe will be a hard irq context on anything but RT. I could be wrong.