From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756149AbZFXBxf (ORCPT ); Tue, 23 Jun 2009 21:53:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753418AbZFXBx1 (ORCPT ); Tue, 23 Jun 2009 21:53:27 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:60562 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752250AbZFXBx0 (ORCPT ); Tue, 23 Jun 2009 21:53:26 -0400 Message-ID: <4A41874B.4090507@cn.fujitsu.com> Date: Wed, 24 Jun 2009 09:54:19 +0800 From: Li Zefan User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: Ingo Molnar CC: Steven Rostedt , Frederic Weisbecker , Liming Wang , LKML Subject: [PATCH 6/7] ftrace: don't manipulate @pos in t_start() References: <4A4186C6.9090706@cn.fujitsu.com> In-Reply-To: <4A4186C6.9090706@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 It's rather confusing that in t_start(), in some cases @pos is incremented, and in some cases it's decremented and then incremented. This patch rewrites t_start() in a much more general way. Thus we fix a bug that if ftrace_filtered == 1, functions have tracer hooks won't be printed, because the branch is always unreachable: static void *t_start(...) { ... if (!p) return t_hash_start(m, pos); return p; } Before: # echo 'sys_open' > /mnt/tracing/set_ftrace_filter # echo 'sys_write:traceon:4' >> /mnt/tracing/set_ftrace_filter sys_open After: # echo 'sys_open' > /mnt/tracing/set_ftrace_filter # echo 'sys_write:traceon:4' >> /mnt/tracing/set_ftrace_filter sys_open sys_write:traceon:count=4 [ Impact: show selected functions when filter is on ] Reviewed-by: Liming Wang Signed-off-by: Li Zefan --- kernel/trace/ftrace.c | 19 ++++++++----------- 1 files changed, 8 insertions(+), 11 deletions(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index c06e9ab..7946938 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1466,8 +1466,6 @@ t_next(struct seq_file *m, void *v, loff_t *pos) iter->pg = iter->pg->next; iter->idx = 0; goto retry; - } else { - iter->idx = -1; } } else { rec = &iter->pg->records[iter->idx++]; @@ -1496,6 +1494,7 @@ static void *t_start(struct seq_file *m, loff_t *pos) { struct ftrace_iterator *iter = m->private; void *p = NULL; + loff_t l; mutex_lock(&ftrace_lock); /* @@ -1507,23 +1506,21 @@ static void *t_start(struct seq_file *m, loff_t *pos) if (*pos > 0) return t_hash_start(m, pos); iter->flags |= FTRACE_ITER_PRINTALL; - (*pos)++; return iter; } if (iter->flags & FTRACE_ITER_HASH) return t_hash_start(m, pos); - if (*pos > 0) { - if (iter->idx < 0) - return p; - (*pos)--; - iter->idx--; + iter->pg = ftrace_pages_start; + iter->idx = 0; + for (l = 0; l <= *pos; ) { + p = t_next(m, p, &l); + if (!p) + break; } - p = t_next(m, p, pos); - - if (!p) + if (!p && iter->flags & FTRACE_ITER_FILTER) return t_hash_start(m, pos); return p; -- 1.5.4.rc3