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author | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2018-03-09 13:19:28 -0500 |
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committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2018-03-14 12:35:39 -0400 |
commit | 80765597bc587feae8dbc8ce97a0f32e12a6e625 (patch) | |
tree | 0a3823a6531798777eed0317f59660ac5495a73b /kernel/trace/trace.h | |
parent | 478325f188657d0e503d1f88cdaf516c792352c5 (diff) | |
download | linux-80765597bc587feae8dbc8ce97a0f32e12a6e625.tar.bz2 |
tracing: Rewrite filter logic to be simpler and faster
Al Viro reviewed the filter logic of ftrace trace events and found it to be
very troubling. It creates a binary tree based on the logic operators and
walks it during tracing. He sent myself and Tom Zanussi a long explanation
(and formal proof) of how to do the string parsing better and end up with a
program array that can be simply iterated to come up with the correct
results.
I took his ideas and his pseudo code and rewrote the filter logic based on
them. In doing so, I was able to remove a lot of code, and have a much more
condensed filter logic in the process. I wrote a very long comment
describing the methadology that Al proposed in my own words. For more info
on how this works, read the comment above predicate_parse().
Suggested-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace/trace.h')
-rw-r--r-- | kernel/trace/trace.h | 15 |
1 files changed, 5 insertions, 10 deletions
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 9de3e2a2f042..6fb46a06c9dc 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -1216,12 +1216,11 @@ struct ftrace_event_field { int is_signed; }; +struct prog_entry; + struct event_filter { - int n_preds; /* Number assigned */ - int a_preds; /* allocated */ - struct filter_pred __rcu *preds; - struct filter_pred __rcu *root; - char *filter_string; + struct prog_entry __rcu *prog; + char *filter_string; }; struct event_subsystem { @@ -1413,12 +1412,8 @@ struct filter_pred { unsigned short *ops; struct ftrace_event_field *field; int offset; - int not; + int not; int op; - unsigned short index; - unsigned short parent; - unsigned short left; - unsigned short right; }; static inline bool is_string_field(struct ftrace_event_field *field) |