From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752630AbZL3JcU (ORCPT ); Wed, 30 Dec 2009 04:32:20 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752566AbZL3JcQ (ORCPT ); Wed, 30 Dec 2009 04:32:16 -0500 Received: from hera.kernel.org ([140.211.167.34]:57482 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752575AbZL3JcO (ORCPT ); Wed, 30 Dec 2009 04:32:14 -0500 Date: Wed, 30 Dec 2009 09:31:25 GMT From: tip-bot for Li Zefan Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, lizf@cn.fujitsu.com, fweisbec@gmail.com, rostedt@goodmis.org, tglx@linutronix.de, mingo@elte.hu, prasad@linux.vnet.ibm.com Reply-To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, lizf@cn.fujitsu.com, fweisbec@gmail.com, rostedt@goodmis.org, tglx@linutronix.de, mingo@elte.hu, prasad@linux.vnet.ibm.com In-Reply-To: <4B3AF1EC.9010608@cn.fujitsu.com> References: <4B3AF1EC.9010608@cn.fujitsu.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:tracing/urgent] ksym_tracer: Fix race when incrementing count Message-ID: Git-Commit-ID: e6d9491bf8ba6728cc86aeabbc688d20ec0563b5 X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: e6d9491bf8ba6728cc86aeabbc688d20ec0563b5 Gitweb: http://git.kernel.org/tip/e6d9491bf8ba6728cc86aeabbc688d20ec0563b5 Author: Li Zefan AuthorDate: Wed, 30 Dec 2009 14:23:40 +0800 Committer: Ingo Molnar CommitDate: Wed, 30 Dec 2009 07:50:49 +0100 ksym_tracer: Fix race when incrementing count 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 Cc: Steven Rostedt Cc: K.Prasad Cc: Frederic Weisbecker LKML-Reference: <4B3AF1EC.9010608@cn.fujitsu.com> Signed-off-by: Ingo Molnar --- 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; }