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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 07827C32753 for ; Wed, 14 Aug 2019 10:41:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DC392204EC for ; Wed, 14 Aug 2019 10:41:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727424AbfHNKlu (ORCPT ); Wed, 14 Aug 2019 06:41:50 -0400 Received: from foss.arm.com ([217.140.110.172]:51906 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726230AbfHNKlt (ORCPT ); Wed, 14 Aug 2019 06:41:49 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id EB6AE28; Wed, 14 Aug 2019 03:41:48 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 210CD3F706; Wed, 14 Aug 2019 03:41:47 -0700 (PDT) From: Mark Rutland To: linux-kernel@vger.kernel.org Cc: ak@linux.intel.com, akpm@linux-foundation.org, bigeasy@linutronix.de, bp@suse.de, catalin.marinas@arm.com, davem@davemloft.net, hch@lst.de, kan.liang@intel.com, mark.rutland@arm.com, mingo@kernel.org, peterz@infradead.org, riel@surriel.com, will@kernel.org Subject: [PATCH 4/9] arm/perf: correctly check for kthreads Date: Wed, 14 Aug 2019 11:41:26 +0100 Message-Id: <20190814104131.20190-5-mark.rutland@arm.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20190814104131.20190-1-mark.rutland@arm.com> References: <20190814104131.20190-1-mark.rutland@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The arm perf_callchain_user() functions looks at current->mm, apparently to determine whether the thread is a kthread without any valid user context. In general, a non-NULL current->mm doesn't imply that current is a kthread, as kthreads can install an mm via use_mm(), and so it's preferable to use is_kthread() to determine whether a thread is a kthread. For consistency, let's use is_kthread() here. Signed-off-by: Mark Rutland Cc: Will Deacon Cc: Ingo Molnar Cc: Peter Zijlstra --- arch/arm/kernel/perf_callchain.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm/kernel/perf_callchain.c b/arch/arm/kernel/perf_callchain.c index 3b69a76d341e..5c920f2c46a8 100644 --- a/arch/arm/kernel/perf_callchain.c +++ b/arch/arm/kernel/perf_callchain.c @@ -71,7 +71,7 @@ perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs perf_callchain_store(entry, regs->ARM_pc); - if (!current->mm) + if (is_kthread(current)) return; tail = (struct frame_tail __user *)regs->ARM_fp - 1; -- 2.11.0