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=-20.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 1BCCBC11F99 for ; Tue, 6 Jul 2021 11:44:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0A06D61ED5 for ; Tue, 6 Jul 2021 11:44:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239852AbhGFLp1 (ORCPT ); Tue, 6 Jul 2021 07:45:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:42402 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235075AbhGFLb0 (ORCPT ); Tue, 6 Jul 2021 07:31:26 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id E758961C99; Tue, 6 Jul 2021 11:22:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1625570545; bh=YfO+ILk/xfSGs3uV8mw0YqMe/28CtrVO21a5gF/WaOo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=P/ATx0Xl5QhkfASoTW7QwiHntcl3mYFctXThIwPsBXWXtcoBLnhhEOjum+qacXi9A 1DYy6RBqAA0B2AB2qdIvlDzdsLZdScFgjaBSCWCHnYbYdLuqpLK60w2dHXHM1U4c3r PfDfkc6boIN1/ru3W1I/0fvcvpiraDcb96+eZIarg1eQWkSKZZK7oj4GNry3Nqdza4 DLatEgqOj2cFhAa61Xok5i4/cVLyIqQ5uM266dcAtFABTG+Wns5ADGGfyAftawUq3K 2FMTjcrl/oOSkdKo7Yoylz6GXdsbkrscQh1tlNDnGkExSq6164MHseK0osxNVNO1bm bMRBApDlxi9/w== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Sebastian Andrzej Siewior , Juri Lelli , Thomas Gleixner , "David S . Miller" , Sasha Levin , netdev@vger.kernel.org Subject: [PATCH AUTOSEL 5.10 016/137] net: Treat __napi_schedule_irqoff() as __napi_schedule() on PREEMPT_RT Date: Tue, 6 Jul 2021 07:20:02 -0400 Message-Id: <20210706112203.2062605-16-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210706112203.2062605-1-sashal@kernel.org> References: <20210706112203.2062605-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Sebastian Andrzej Siewior [ Upstream commit 8380c81d5c4fced6f4397795a5ae65758272bbfd ] __napi_schedule_irqoff() is an optimized version of __napi_schedule() which can be used where it is known that interrupts are disabled, e.g. in interrupt-handlers, spin_lock_irq() sections or hrtimer callbacks. On PREEMPT_RT enabled kernels this assumptions is not true. Force- threaded interrupt handlers and spinlocks are not disabling interrupts and the NAPI hrtimer callback is forced into softirq context which runs with interrupts enabled as well. Chasing all usage sites of __napi_schedule_irqoff() is a whack-a-mole game so make __napi_schedule_irqoff() invoke __napi_schedule() for PREEMPT_RT kernels. The callers of ____napi_schedule() in the networking core have been audited and are correct on PREEMPT_RT kernels as well. Reported-by: Juri Lelli Signed-off-by: Sebastian Andrzej Siewior Reviewed-by: Thomas Gleixner Reviewed-by: Juri Lelli Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/core/dev.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index 0c9ce36afc8c..2fdf30eefc59 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -6433,11 +6433,18 @@ EXPORT_SYMBOL(napi_schedule_prep); * __napi_schedule_irqoff - schedule for receive * @n: entry to schedule * - * Variant of __napi_schedule() assuming hard irqs are masked + * Variant of __napi_schedule() assuming hard irqs are masked. + * + * On PREEMPT_RT enabled kernels this maps to __napi_schedule() + * because the interrupt disabled assumption might not be true + * due to force-threaded interrupts and spinlock substitution. */ void __napi_schedule_irqoff(struct napi_struct *n) { - ____napi_schedule(this_cpu_ptr(&softnet_data), n); + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + ____napi_schedule(this_cpu_ptr(&softnet_data), n); + else + __napi_schedule(n); } EXPORT_SYMBOL(__napi_schedule_irqoff); -- 2.30.2