Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751549AbdIOShM (ORCPT ); Fri, 15 Sep 2017 14:37:12 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:51210 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751201AbdIOShL (ORCPT ); Fri, 15 Sep 2017 14:37:11 -0400 Message-ID: <59BC1D7F.4090107@arm.com> Date: Fri, 15 Sep 2017 19:35:43 +0100 From: James Morse User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.6.0 MIME-Version: 1.0 To: Stephen Boyd CC: Will Deacon , Catalin Marinas , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Tyler Baicar , Jonathan Zhang Subject: Re: [PATCH] arm64: Unconditionally support ARCH_HAVE_NMI_SAFE_CMPXCHG References: <20170915011915.7993-1-sboyd@codeaurora.org> In-Reply-To: <20170915011915.7993-1-sboyd@codeaurora.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1271 Lines: 45 Hi Stephen, On 15/09/17 02:19, Stephen Boyd wrote: > From what I can see there isn't anything about ACPI_APEI_SEA that > means the arm64 architecture can or cannot support NMI safe > cmpxchg, so the if condition here is not important. Yup, it was to match 'HAVE_NMI', which was new with ACPI_APEI_SEA and pulls in some printk() stuff. ... how come you don't need to change HAVE_NMI too? > Let's remove > it. Doing that allows us to support ftrace histograms via > CONFIG_HIST_TRIGGERS that depends on the arch having this config > selected. What does CONFIG_HIST_TRIGGERS need this for? I can't see any cmpxchg use in kernel/trace/trace_events_hist.c Regardless, Acked-by: James Morse Thanks, James > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 0df64a6a56d4..27ce2ab7b080 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -21,7 +21,7 @@ config ARM64 > select ARCH_HAS_STRICT_KERNEL_RWX > select ARCH_HAS_STRICT_MODULE_RWX > select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST > - select ARCH_HAVE_NMI_SAFE_CMPXCHG if ACPI_APEI_SEA > + select ARCH_HAVE_NMI_SAFE_CMPXCHG > select ARCH_USE_CMPXCHG_LOCKREF > select ARCH_SUPPORTS_MEMORY_FAILURE > select ARCH_SUPPORTS_ATOMIC_RMW >