From nobody Sun Feb 8 11:40:39 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id ACB54EB64D7 for ; Tue, 20 Jun 2023 13:01:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232844AbjFTNBp (ORCPT ); Tue, 20 Jun 2023 09:01:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41596 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232662AbjFTNBR (ORCPT ); Tue, 20 Jun 2023 09:01:17 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BB03119AB; Tue, 20 Jun 2023 06:00:53 -0700 (PDT) Date: Tue, 20 Jun 2023 13:00:51 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1687266052; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=FqBcLkeqh5aYZLHq2KtPr0BsS5m73Epy5K0pPEmT8hY=; b=YxdR8RPnZuF2m0qhyttRSqTE0GAnxOzZMGGaR+mZGxt+pznxLT8620EZuTHDN4XdELdGFM wWHpkZuswoq22IU5M4TXUS+Bc7tLdTxvqLfoQqPnIkCihTldbhKkdAV699HKTB7+c15V9D WjxApCK0zbfBS4XDw6GlNM3xeLVVOJ42i5e4GuMDaWqRJf6XMbOL2iTO0BuS0gVWTRIs0H f7LxyEm2dJc/9sevhAzNWwR7OWo9V/ck//uP4c+bHzWxJKKr9lcXeZUEjvL2FXhDFu6NIm wbUQCQQJyxkAgVs/CYny8/VgNzAvIwPPtm2oGopeYrMUEELi86gKjBKyy2lyYw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1687266052; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=FqBcLkeqh5aYZLHq2KtPr0BsS5m73Epy5K0pPEmT8hY=; b=UGUxET9Ks98DFFpDaso9wT9wK9vHuEaJMlVWCgZMtbcI8VQ4RqD5vHTMJzNbAJWRVpYJnY C0c2iap+OtZC8aDg== From: "tip-bot2 for Thomas Gleixner" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/core] x86/smp: Remove pointless wmb()s from native_stop_other_cpus() Cc: Thomas Gleixner , "Borislav Petkov (AMD)" , stable@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20230615193330.378358382@linutronix.de> References: <20230615193330.378358382@linutronix.de> MIME-Version: 1.0 Message-ID: <168726605177.404.10010804348087139293.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the x86/core branch of tip: Commit-ID: 2affa6d6db28855e6340b060b809c23477aa546e Gitweb: https://git.kernel.org/tip/2affa6d6db28855e6340b060b809c2347= 7aa546e Author: Thomas Gleixner AuthorDate: Thu, 15 Jun 2023 22:33:54 +02:00 Committer: Thomas Gleixner CommitterDate: Tue, 20 Jun 2023 14:51:46 +02:00 x86/smp: Remove pointless wmb()s from native_stop_other_cpus() The wmb()s before sending the IPIs are not synchronizing anything. If at all then the apic IPI functions have to provide or act as appropriate barriers. Remove these cargo cult barriers which have no explanation of what they are synchronizing. Signed-off-by: Thomas Gleixner Reviewed-by: Borislav Petkov (AMD) Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20230615193330.378358382@linutronix.de --- arch/x86/kernel/smp.c | 6 ------ 1 file changed, 6 deletions(-) diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c index 935bc65..d842875 100644 --- a/arch/x86/kernel/smp.c +++ b/arch/x86/kernel/smp.c @@ -184,9 +184,6 @@ static void native_stop_other_cpus(int wait) cpumask_clear_cpu(cpu, &cpus_stop_mask); =20 if (!cpumask_empty(&cpus_stop_mask)) { - /* sync above data before sending IRQ */ - wmb(); - apic_send_IPI_allbutself(REBOOT_VECTOR); =20 /* @@ -208,9 +205,6 @@ static void native_stop_other_cpus(int wait) * CPUs to stop. */ if (!smp_no_nmi_ipi && !register_stop_handler()) { - /* Sync above data before sending IRQ */ - wmb(); - pr_emerg("Shutting down cpus with NMI\n"); =20 for_each_cpu(cpu, &cpus_stop_mask)