From: Lai Jiangshan Date: Tue, 2 Mar 2010 09:54:50 +0000 (+0800) Subject: tracing: Fix warning in s_next of trace file ops X-Git-Tag: upstream/snapshot3+hdmi~15076^2~6^2 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=ac91d85456372a90af5b85eb6620fd2efb1e431b;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git tracing: Fix warning in s_next of trace file ops This warning in s_next() can be triggered by lseek(): [] ? s_next+0x77/0x80 [] warn_slowpath_common+0x81/0xa0 [] ? s_next+0x77/0x80 [] warn_slowpath_null+0x1a/0x20 [] s_next+0x77/0x80 [] traverse+0x117/0x200 [] seq_lseek+0xa3/0x120 [] ? seq_lseek+0x0/0x120 [] vfs_llseek+0x41/0x50 [] sys_llseek+0x66/0xa0 [] 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(). Cc: stable@kernel.org Signed-off-by: Lai Jiangshan LKML-Reference: <4B8CE06A.9090207@cn.fujitsu.com> Signed-off-by: Steven Rostedt --- 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)) ;