mirrors/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2025-11-04 02:30:34 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions

tracing: Rewrite filter logic to be simpler and faster

Browse source 
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>
This commit is contained in:
Steven Rostedt (VMware) 2018-03-09 13:19:28 -05:00
parent 478325f188
commit 80765597bc
2 changed files with 1005 additions and 1223 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

15
kernel/trace/trace.h
View file

@ -1216,12 +1216,11 @@ struct ftrace_event_field {
int is_signed; int is_signed;
}; };
struct prog_entry;
struct event_filter { struct event_filter {
int n_preds; /* Number assigned */ struct prog_entry __rcu *prog;
int a_preds; /* allocated */ char *filter_string;
struct filter_pred __rcu *preds;
struct filter_pred __rcu *root;
char *filter_string;
}; };
struct event_subsystem { struct event_subsystem {
@ -1413,12 +1412,8 @@ struct filter_pred {
unsigned short *ops; unsigned short *ops;
struct ftrace_event_field *field; struct ftrace_event_field *field;
int offset; int offset;
int not; int not;
int op; 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) static inline bool is_string_field(struct ftrace_event_field *field)

2213
kernel/trace/trace_events_filter.c
View file

File diff suppressed because it is too large Load diff