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author | Li Zefan <lizf@cn.fujitsu.com> | 2009-08-07 10:33:43 +0800 |
---|---|---|
committer | Steven Rostedt <rostedt@goodmis.org> | 2009-08-26 00:32:07 -0400 |
commit | 87a342f5db69d53ea70493bb1ec69c9047677038 (patch) | |
tree | 89ec97b3a32d6508d10f1598201e48a24c08c46e /include/linux/ftrace_event.h | |
parent | 43b51ead3f752a3935116e5b1a94254b8573734f (diff) | |
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tracing/filters: Support filtering for char * strings
Usually, char * entries are dangerous in traces because the string
can be released whereas a pointer to it can still wait to be read from
the ring buffer.
But sometimes we can assume it's safe, like in case of RO data
(eg: __file__ or __line__, used in bkl trace event). If these RO data
are in a module and so is the call to the trace event, then it's safe,
because the ring buffer will be flushed once this module get unloaded.
To allow char * to be treated as a string:
TRACE_EVENT(...,
TP_STRUCT__entry(
__field_ext(const char *, name, FILTER_PTR_STRING)
...
)
...
);
The filtering will not dereference "char *" unless the developer
explicitly sets FILTER_PTR_STR in __field_ext.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4A7B9287.90205@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'include/linux/ftrace_event.h')
-rw-r--r-- | include/linux/ftrace_event.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h index 0440bea..ace2da9 100644 --- a/include/linux/ftrace_event.h +++ b/include/linux/ftrace_event.h @@ -144,6 +144,7 @@ enum { FILTER_OTHER = 0, FILTER_STATIC_STRING, FILTER_DYN_STRING, + FILTER_PTR_STRING, }; extern int trace_define_field(struct ftrace_event_call *call, |