From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753477AbYKPFAP (ORCPT ); Sun, 16 Nov 2008 00:00:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753406AbYKPFAA (ORCPT ); Sun, 16 Nov 2008 00:00:00 -0500 Received: from fg-out-1718.google.com ([72.14.220.154]:35141 "EHLO fg-out-1718.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751916AbYKPE77 (ORCPT ); Sat, 15 Nov 2008 23:59:59 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:cc:subject :content-type:content-transfer-encoding; b=ROau2neGJ5z9Jyf1KGN7290uYuxoPWpyI23wTKK45rFw24fDLiLs04S7Z7GMIlbXHe h278zPuzIkPfeCLx5uq0NN3K9Bm8N3VfWofi7hppxWBmG/y4vbU+nhuh//SoTdH1Wln0 anQv2Z1n76HLvPcvDR2+fw+aDoEF6HCjFfxqg= Message-ID: <491FA8C8.1040905@gmail.com> Date: Sun, 16 Nov 2008 05:59:52 +0100 From: Frederic Weisbecker User-Agent: Thunderbird 2.0.0.17 (X11/20080925) MIME-Version: 1.0 To: Ingo Molnar CC: Steven Rostedt , Linux Kernel Subject: [PATCH 3/4] tracing/branch-tracer: Fix a trace recursion on branch tracer Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Impact: Make the branch tracer use raw irq save/restore When the branch tracer inserts an event through probe_likely_condition(), it calls local_irq_save() and then results in a trace recursion. local_irq_save() -> trace_hardirqs_off() -> trace_hardirqs_off_caller() -> unlikely() The trace_branch.c file is protected by DISABLE_BRANCH_PROFILING but that doesn't prevent from external call to functions that use unlikely(). My box crashed each time I tried to set this tracer (sudden and hard reboot). Signed-off-by: Frederic Weisbecker Cc: Steven Rostedt --- kernel/trace/trace_branch.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/trace/trace_branch.c b/kernel/trace/trace_branch.c index 44bd395..23f9b02 100644 --- a/kernel/trace/trace_branch.c +++ b/kernel/trace/trace_branch.c @@ -41,7 +41,7 @@ probe_likely_condition(struct ftrace_branch_data *f, int val, int expect) if (unlikely(!tr)) return; - local_irq_save(flags); + raw_local_irq_save(flags); cpu = raw_smp_processor_id(); if (atomic_inc_return(&tr->data[cpu]->disabled) != 1) goto out; @@ -73,7 +73,7 @@ probe_likely_condition(struct ftrace_branch_data *f, int val, int expect) out: atomic_dec(&tr->data[cpu]->disabled); - local_irq_restore(flags); + raw_local_irq_restore(flags); } static inline -- 1.5.2.5