From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752473AbZL3GXw (ORCPT ); Wed, 30 Dec 2009 01:23:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752428AbZL3GXv (ORCPT ); Wed, 30 Dec 2009 01:23:51 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:56824 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752453AbZL3GXu (ORCPT ); Wed, 30 Dec 2009 01:23:50 -0500 Message-ID: <4B3AF1EC.9010608@cn.fujitsu.com> Date: Wed, 30 Dec 2009 14:23:40 +0800 From: Li Zefan User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1b3pre) Gecko/20090513 Fedora/3.0-2.3.beta2.fc11 Thunderbird/3.0b2 MIME-Version: 1.0 To: Frederic Weisbecker CC: Steven Rostedt , Ingo Molnar , "K.Prasad" , LKML Subject: [PATCH 3/4] ksym_tracer: Fix race when incrementing count References: <4B3AF19E.1010201@cn.fujitsu.com> In-Reply-To: <4B3AF19E.1010201@cn.fujitsu.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We are under rcu read section but not holding the write lock, so count++ is not atomic. Use atomic64_t instead. Signed-off-by: Li Zefan --- kernel/trace/trace_ksym.c | 12 +++++++----- 1 files changed, 7 insertions(+), 5 deletions(-) diff --git a/kernel/trace/trace_ksym.c b/kernel/trace/trace_ksym.c index 160a8d8..67d79f7 100644 --- a/kernel/trace/trace_ksym.c +++ b/kernel/trace/trace_ksym.c @@ -32,6 +32,8 @@ #include #include +#include + /* * For now, let us restrict the no. of symbols traced simultaneously to number * of available hardware breakpoint registers. @@ -44,7 +46,7 @@ struct trace_ksym { struct perf_event **ksym_hbp; struct perf_event_attr attr; #ifdef CONFIG_PROFILE_KSYM_TRACER - unsigned long counter; + atomic64_t counter; #endif struct hlist_node ksym_hlist; }; @@ -69,9 +71,8 @@ void ksym_collect_stats(unsigned long hbp_hit_addr) rcu_read_lock(); hlist_for_each_entry_rcu(entry, node, &ksym_filter_head, ksym_hlist) { - if ((entry->attr.bp_addr == hbp_hit_addr) && - (entry->counter <= MAX_UL_INT)) { - entry->counter++; + if (entry->attr.bp_addr == hbp_hit_addr) { + atomic64_inc(&entry->counter); break; } } @@ -501,7 +502,8 @@ static int ksym_tracer_stat_show(struct seq_file *m, void *v) seq_printf(m, " %-36s", fn_name); else seq_printf(m, " %-36s", ""); - seq_printf(m, " %15lu\n", entry->counter); + seq_printf(m, " %15llu\n", + (unsigned long long)atomic64_read(&entry->counter)); return 0; } -- 1.6.3