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=-3.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 5131CC34047 for ; Wed, 19 Feb 2020 15:14:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2810B24670 for ; Wed, 19 Feb 2020 15:14:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="AB3UkHBv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727747AbgBSPO3 (ORCPT ); Wed, 19 Feb 2020 10:14:29 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:36008 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727656AbgBSPO1 (ORCPT ); Wed, 19 Feb 2020 10:14:27 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-Id:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To; bh=eg1eQJ//SprCAwF+hza1bycJo6HO/QF3v0sPZ8+K7tU=; b=AB3UkHBv4jxJTjf4ebuLCqaJJu Gwq824YHf2XWIWgNDSWUeHfWS/ws+dyvj196JS8sitvvfuPYgjLkOEWU77HOhPnOfcn9IIBeQJs/m Bef8GUrIJY9xClyu46Qyyc5gWD6zGSoKKb7nlO2S9qXW3WsSzj9qbgNXsNj2fVJK2z+WX7dNvhJml jgqz5VR+6gDG6aXxyoilDI4RPVeSDP6vPkFeGNVxYJ0uDsTps/V/+H3RSKGo/yXWMdG2gm0HjNcyg nfe8KvZvhf9HjbgV7tpScL1V/MgJ+GSWcHdY4DlNLc6GmaY6gq5rtFVrhTAqxYM5WQWnnNtZa0ARp 7UpKEEIA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1j4R39-000112-99; Wed, 19 Feb 2020 15:14:07 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id DB35030743A; Wed, 19 Feb 2020 16:12:11 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id 7785429E09C0A; Wed, 19 Feb 2020 16:14:03 +0100 (CET) Message-Id: <20200219150744.661923520@infradead.org> User-Agent: quilt/0.65 Date: Wed, 19 Feb 2020 15:47:29 +0100 From: Peter Zijlstra To: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, rostedt@goodmis.org Cc: peterz@infradead.org, mingo@kernel.org, joel@joelfernandes.org, gregkh@linuxfoundation.org, gustavo@embeddedor.com, tglx@linutronix.de, paulmck@kernel.org, josh@joshtriplett.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, luto@kernel.org, tony.luck@intel.com, frederic@kernel.org, dan.carpenter@oracle.com, mhiramat@kernel.org Subject: [PATCH v3 05/22] rcu: Make RCU IRQ enter/exit functions rely on in_nmi() References: <20200219144724.800607165@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Paul E. McKenney The rcu_nmi_enter_common() and rcu_nmi_exit_common() functions take an "irq" parameter that indicates whether these functions are invoked from an irq handler (irq==true) or an NMI handler (irq==false). However, recent changes have applied notrace to a few critical functions such that rcu_nmi_enter_common() and rcu_nmi_exit_common() many now rely on in_nmi(). Note that in_nmi() works no differently than before, but rather that tracing is now prohibited in code regions where in_nmi() would incorrectly report NMI state. This commit therefore removes the "irq" parameter and inlines rcu_nmi_enter_common() and rcu_nmi_exit_common() into rcu_nmi_enter() and rcu_nmi_exit(), respectively. Signed-off-by: Paul E. McKenney Signed-off-by: Peter Zijlstra (Intel) --- kernel/rcu/tree.c | 45 ++++++++++++++------------------------------- 1 file changed, 14 insertions(+), 31 deletions(-) --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -614,16 +614,18 @@ void rcu_user_enter(void) } #endif /* CONFIG_NO_HZ_FULL */ -/* +/** + * rcu_nmi_exit - inform RCU of exit from NMI context + * * If we are returning from the outermost NMI handler that interrupted an * RCU-idle period, update rdp->dynticks and rdp->dynticks_nmi_nesting * to let the RCU grace-period handling know that the CPU is back to * being RCU-idle. * - * If you add or remove a call to rcu_nmi_exit_common(), be sure to test + * If you add or remove a call to rcu_nmi_exit(), be sure to test * with CONFIG_RCU_EQS_DEBUG=y. */ -static __always_inline void rcu_nmi_exit_common(bool irq) +void rcu_nmi_exit(void) { struct rcu_data *rdp = this_cpu_ptr(&rcu_data); @@ -651,27 +653,16 @@ static __always_inline void rcu_nmi_exit trace_rcu_dyntick(TPS("Startirq"), rdp->dynticks_nmi_nesting, 0, atomic_read(&rdp->dynticks)); WRITE_ONCE(rdp->dynticks_nmi_nesting, 0); /* Avoid store tearing. */ - if (irq) + if (!in_nmi()) rcu_prepare_for_idle(); rcu_dynticks_eqs_enter(); - if (irq) + if (!in_nmi()) rcu_dynticks_task_enter(); } /** - * rcu_nmi_exit - inform RCU of exit from NMI context - * - * If you add or remove a call to rcu_nmi_exit(), be sure to test - * with CONFIG_RCU_EQS_DEBUG=y. - */ -void rcu_nmi_exit(void) -{ - rcu_nmi_exit_common(false); -} - -/** * rcu_irq_exit - inform RCU that current CPU is exiting irq towards idle * * Exit from an interrupt handler, which might possibly result in entering @@ -693,7 +684,7 @@ void rcu_nmi_exit(void) void rcu_irq_exit(void) { lockdep_assert_irqs_disabled(); - rcu_nmi_exit_common(true); + rcu_nmi_exit(); } /* @@ -777,7 +768,7 @@ void rcu_user_exit(void) #endif /* CONFIG_NO_HZ_FULL */ /** - * rcu_nmi_enter_common - inform RCU of entry to NMI context + * rcu_nmi_enter - inform RCU of entry to NMI context * @irq: Is this call from rcu_irq_enter? * * If the CPU was idle from RCU's viewpoint, update rdp->dynticks and @@ -786,10 +777,10 @@ void rcu_user_exit(void) * long as the nesting level does not overflow an int. (You will probably * run out of stack space first.) * - * If you add or remove a call to rcu_nmi_enter_common(), be sure to test + * If you add or remove a call to rcu_nmi_enter(), be sure to test * with CONFIG_RCU_EQS_DEBUG=y. */ -static __always_inline void rcu_nmi_enter_common(bool irq) +void rcu_nmi_enter(void) { long incby = 2; struct rcu_data *rdp = this_cpu_ptr(&rcu_data); @@ -807,12 +798,12 @@ static __always_inline void rcu_nmi_ente */ if (rcu_dynticks_curr_cpu_in_eqs()) { - if (irq) + if (!in_nmi()) rcu_dynticks_task_exit(); rcu_dynticks_eqs_exit(); - if (irq) + if (!in_nmi()) rcu_cleanup_after_idle(); incby = 1; @@ -834,14 +825,6 @@ static __always_inline void rcu_nmi_ente rdp->dynticks_nmi_nesting + incby); barrier(); } - -/** - * rcu_nmi_enter - inform RCU of entry to NMI context - */ -void rcu_nmi_enter(void) -{ - rcu_nmi_enter_common(false); -} NOKPROBE_SYMBOL(rcu_nmi_enter); /** @@ -869,7 +852,7 @@ NOKPROBE_SYMBOL(rcu_nmi_enter); void rcu_irq_enter(void) { lockdep_assert_irqs_disabled(); - rcu_nmi_enter_common(true); + rcu_nmi_enter(); } /*