tracing/filter: Optimize short ciruit check

The test if we should break out early for OR and AND operations
can be optimized by comparing the current result with
  (pred->op == OP_OR)

That is if the result is true and the op is an OP_OR, or
if the result is false and the op is not an OP_OR (thus an OP_AND)
we can break out early in either case. Otherwise we continue
processing.

Cc: Tom Zanussi <tzanussi@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 9 insertions, 3 deletions

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 10390491b6d0..0a3e0502b507 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -426,9 +426,15 @@ int filter_match_preds(struct event_filter *filter, void *rec)
                                                pred->parent, &move);
                         continue;
                 case MOVE_UP_FROM_LEFT:
-                        /* Check for short circuits */
-                        if ((match && pred->op == OP_OR) ||
-                            (!match && pred->op == OP_AND)) {
+                        /*
+                         * Check for short circuits.
+                         *
+                         * Optimization: !!match == (pred->op == OP_OR)
+                         *   is the same as:
+                         * if ((match && pred->op == OP_OR) ||
+                         *     (!match && pred->op == OP_AND))
+                         */
+                        if (!!match == (pred->op == OP_OR)) {
                                 if (pred == root)
                                         break;
                                 pred = get_pred_parent(pred, preds,