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authorLai Jiangshan <laijs@cn.fujitsu.com>2010-03-02 17:54:50 +0800
committerGreg Kroah-Hartman <gregkh@suse.de>2010-04-01 16:01:16 -0700
commitfe030f50c598ffd9476da37d35a7dd7301487795 (patch)
tree728d2b4462739ee00803f2865bffe2654a1890a3
parenta86a83770fe3cc858f91b0ae6406477dc8d0bf17 (diff)
tracing: Fix warning in s_next of trace file ops
commit ac91d85456372a90af5b85eb6620fd2efb1e431b upstream. 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 The iterator "leftover" variable is zeroed in the opening of the trace file. But lseek can call s_start() which will call s_next() without reseting the "leftover" variable back to zero, which might trigger the WARN_ON_ONCE(iter->leftover) that is in s_next(). Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> LKML-Reference: <4B8CE06A.9090207@cn.fujitsu.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--kernel/trace/trace.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index eac6875cb990..1069dcb935e3 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1628,6 +1628,7 @@ 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))
;