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ftrace: Using FTRACE_WARN_ON() to check "freed record" in ftrace_release()

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"Because when we call ftrace_free_rec we change the rec->ip to point to the
  next record in the chain. Something is very wrong if rec->ip >= s &&
  rec->ip < e and the record is already free."

 "Note, use FTRACE_WARN_ON() macro. This way it shuts down ftrace if it is
  hit and helps to avoid further damage later."
                   -- Steven Rostedt <rostedt@goodmis.org>

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
This commit is contained in:
Zhaolei 2009-03-25 12:06:05 +08:00 committed by Steven Rostedt
parent 759ee0915d
commit 2a4efa4245
1 changed files with 7 additions and 2 deletions
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9
kernel/trace/ftrace.c
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@ -358,9 +358,14 @@ void ftrace_release(void *start, unsigned long size)
mutex_lock(&ftrace_lock);
do_for_each_ftrace_rec(pg, rec) {
if ((rec->ip >= s) && (rec->ip < e) &&
!(rec->flags & FTRACE_FL_FREE))
if ((rec->ip >= s) && (rec->ip < e)) {
/*
* rec->ip is changed in ftrace_free_rec()
* It should not between s and e if record was freed.
*/
FTRACE_WARN_ON(rec->flags & FTRACE_FL_FREE);
ftrace_free_rec(rec);
}
} while_for_each_ftrace_rec();
mutex_unlock(&ftrace_lock);
}