From 80765597bc587feae8dbc8ce97a0f32e12a6e625 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Fri, 9 Mar 2018 13:19:28 -0500 Subject: 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 Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace.h | 15 +++++---------- 1 file changed, 5 insertions(+), 10 deletions(-) (limited to 'kernel/trace/trace.h') 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) -- cgit v1.2.3