From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755237Ab0ASHfa (ORCPT ); Tue, 19 Jan 2010 02:35:30 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754964Ab0ASHfY (ORCPT ); Tue, 19 Jan 2010 02:35:24 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:49871 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1755092Ab0ASHfU (ORCPT ); Tue, 19 Jan 2010 02:35:20 -0500 Message-ID: <4B556064.7080700@cn.fujitsu.com> Date: Tue, 19 Jan 2010 15:33:56 +0800 From: Lai Jiangshan User-Agent: Thunderbird 2.0.0.6 (Windows/20070728) MIME-Version: 1.0 To: Steven Rostedt , linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton , Frederic Weisbecker Subject: [PATCH 1/6] : bug fix, remove partial zero out 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 partial-zero-out a struct is very dangerous, we should zero out field by field directly when need. partial-zero-out for struct trace_iterator exists when ftrace was first introduced into mainline kernel. But in this few years, the code of ftrace is changed a lot, and: 1) partial-zero-out for struct trace_iterator has a bug now, cpumask_var_t started should not be zeroed out. 2) I viewed the codes and found that fields below "/* The below is zeroed out in pipe_read */" don't need to be zeroed out or initialized now. So, we remove the code of "partial zero out" Signed-off-by: Lai Jiangshan --- diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h index 3ca9485..c6d0e1a 100644 --- a/include/linux/ftrace_event.h +++ b/include/linux/ftrace_event.h @@ -54,7 +54,6 @@ struct trace_iterator { struct ring_buffer_iter *buffer_iter[NR_CPUS]; unsigned long iter_flags; - /* The below is zeroed out in pipe_read */ struct trace_seq seq; struct trace_entry *ent; int leftover; diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 5314c90..27fecf8 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3124,12 +3124,6 @@ waitagain: if (cnt >= PAGE_SIZE) cnt = PAGE_SIZE - 1; - /* reset all but tr, trace, and overruns */ - memset(&iter->seq, 0, - sizeof(struct trace_iterator) - - offsetof(struct trace_iterator, seq)); - iter->pos = -1; - trace_event_read_lock(); trace_access_lock(iter->cpu_file); while (find_next_entry_inc(iter) != NULL) { @@ -4398,12 +4392,7 @@ static void __ftrace_dump(bool disable_tracing) cnt++; - /* reset all but tr, trace, and overruns */ - memset(&iter.seq, 0, - sizeof(struct trace_iterator) - - offsetof(struct trace_iterator, seq)); iter.iter_flags |= TRACE_FILE_LAT_FMT; - iter.pos = -1; if (find_next_entry_inc(&iter) != NULL) { int ret;