From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932515AbeASRmJ (ORCPT ); Fri, 19 Jan 2018 12:42:09 -0500 Received: from mail.kernel.org ([198.145.29.99]:43902 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932166AbeASRmB (ORCPT ); Fri, 19 Jan 2018 12:42:01 -0500 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EE15021719 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=rostedt@goodmis.org Message-Id: <20180119174159.986942954@goodmis.org> User-Agent: quilt/0.63-1 Date: Fri, 19 Jan 2018 12:41:32 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Linus Torvalds , Ingo Molnar , Andrew Morton Subject: [PATCH 1/2] ring-buffer: Fix duplicate results in mapping context to bits in recursive lock References: <20180119174131.963752801@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Disposition: inline; filename=0001-ring-buffer-Fix-duplicate-results-in-mapping-context.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Steven Rostedt (VMware)" In bringing back the context checks, the code checks first if its normal (non-interrupt) context, and then for NMI then IRQ then softirq. The final check is redundant. Since the if branch is only hit if the context is one of NMI, IRQ, or SOFTIRQ, if it's not NMI or IRQ there's no reason to check if it is SOFTIRQ. The current code returns the same result even if its not a SOFTIRQ. Which is confusing. pc & SOFTIRQ_OFFSET ? 2 : RB_CTX_SOFTIRQ Is redundant as RB_CTX_SOFTIRQ *is* 2! Fixes: a0e3a18f4baf ("ring-buffer: Bring back context level recursive checks") Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/ring_buffer.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 0cddf60186da..5af2842dea96 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -2579,8 +2579,7 @@ trace_recursive_lock(struct ring_buffer_per_cpu *cpu_buffer) bit = RB_CTX_NORMAL; else bit = pc & NMI_MASK ? RB_CTX_NMI : - pc & HARDIRQ_MASK ? RB_CTX_IRQ : - pc & SOFTIRQ_OFFSET ? 2 : RB_CTX_SOFTIRQ; + pc & HARDIRQ_MASK ? RB_CTX_IRQ : RB_CTX_SOFTIRQ; if (unlikely(val & (1 << bit))) return 1; -- 2.13.2