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From: Lai Jiangshan <laijs@cn.fujitsu.com>
To: Steven Rostedt <rostedt@goodmis.org>, Ingo Molnar <mingo@elte.hu>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: [PATCH] tracing: fix warning in s_next
Date: Tue, 02 Mar 2010 17:54:50 +0800	[thread overview]
Message-ID: <4B8CE06A.9090207@cn.fujitsu.com> (raw)

This warning in s_next() can be triggered by lseek():
 [<c018b3f7>] ? s_next+0x77/0x80
 [<c013e3c1>] warn_slowpath_common+0x81/0xa0
 [<c018b3f7>] ? s_next+0x77/0x80
 [<c013e3fa>] warn_slowpath_null+0x1a/0x20
 [<c018b3f7>] s_next+0x77/0x80
 [<c01efa77>] traverse+0x117/0x200
 [<c01eff13>] seq_lseek+0xa3/0x120
 [<c01efe70>] ? seq_lseek+0x0/0x120
 [<c01d7081>] vfs_llseek+0x41/0x50
 [<c01d8116>] sys_llseek+0x66/0xa0
 [<c0102bd0>] sysenter_do_call+0x12/0x26

It is because s_start() calls s_next() without reset leftover.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 032c57c..5edf410 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1703,6 +1703,7 @@ static void *s_start(struct seq_file *m, loff_t *pos)
 
 		ftrace_enable_cpu();
 
+		iter->leftover = 0;
 		for (p = iter; p && l < *pos; p = s_next(m, p, &l))
 			;
 

             reply	other threads:[~2010-03-02  9:55 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-03-02  9:54 Lai Jiangshan [this message]
2010-03-02 14:33 ` [PATCH] tracing: fix warning in s_next Steven Rostedt
2010-03-04 16:30 ` [tip:tracing/urgent] tracing: Fix warning in s_next of trace file ops tip-bot for Lai Jiangshan

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