From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Tue, 20 Nov 2012 21:21:18 +0000 (-0500)
Subject: Filter: use only single lower bit of filter return value
X-Git-Tag: v2.1.0-rc2~4
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=8a92ed2aba5250d41e31d1af5620a2317105c91a;p=lttng-ust.git

Filter: use only single lower bit of filter return value

Implementation change: use a uint64_t as filter return value, and test
with a mask for this bit. This reserves other bits for future use.

Reviewed-by: David Goulet <dgoulet@efficios.com>
Reviewed-by: Christian Babeux <christian.babeux@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/include/lttng/ust-events.h b/include/lttng/ust-events.h
index f501fd14..331506bd 100644
--- a/include/lttng/ust-events.h
+++ b/include/lttng/ust-events.h
@@ -299,10 +299,19 @@ struct lttng_ust_filter_bytecode_node {
 	struct lttng_ust_filter_bytecode bc;
 };
 
+/*
+ * Filter return value masks.
+ */
+enum lttng_filter_ret {
+	LTTNG_FILTER_DISCARD = 0,
+	LTTNG_FILTER_RECORD_FLAG = (1ULL << 0),
+	/* Other bits are kept for future use. */
+};
+
 struct lttng_bytecode_runtime {
 	/* Associated bytecode */
 	struct lttng_ust_filter_bytecode_node *bc;
-	int (*filter)(void *filter_data, const char *filter_stack_data);
+	uint64_t (*filter)(void *filter_data, const char *filter_stack_data);
 	int link_failed;
 	struct cds_list_head node;	/* list of bytecode runtime in event */
 };
diff --git a/include/lttng/ust-tracepoint-event.h b/include/lttng/ust-tracepoint-event.h
index fdecda70..8f804d62 100644
--- a/include/lttng/ust-tracepoint-event.h
+++ b/include/lttng/ust-tracepoint-event.h
@@ -489,16 +489,16 @@ void __event_probe__##_provider##___##_name(_TP_ARGS_DATA_PROTO(_args))	      \
 		return;							      \
 	if (caa_unlikely(!cds_list_empty(&__event->bytecode_runtime_head))) { \
 		struct lttng_bytecode_runtime *bc_runtime;		      \
-		int __filter_result = 0;				      \
+		int __filter_record = 0;				      \
 									      \
 		__event_prepare_filter_stack__##_provider##___##_name(__stackvar.__filter_stack_data, \
 			_TP_ARGS_DATA_VAR(_args));			      \
 		cds_list_for_each_entry_rcu(bc_runtime, &__event->bytecode_runtime_head, node) { \
 			if (caa_unlikely(bc_runtime->filter(bc_runtime,	      \
-					__stackvar.__filter_stack_data)))     \
-				__filter_result = 1;			      \
+					__stackvar.__filter_stack_data) & LTTNG_FILTER_RECORD_FLAG)) \
+				__filter_record = 1;			      \
 		}							      \
-		if (caa_likely(!__filter_result))			      \
+		if (caa_likely(!__filter_record))			      \
 			return;						      \
 	}								      \
 	__event_len = __event_get_size__##_provider##___##_name(__stackvar.__dynamic_len, \
diff --git a/liblttng-ust/lttng-filter-interpreter.c b/liblttng-ust/lttng-filter-interpreter.c
index e6e96dbf..690ebde9 100644
--- a/liblttng-ust/lttng-filter-interpreter.c
+++ b/liblttng-ust/lttng-filter-interpreter.c
@@ -105,7 +105,7 @@ int stack_strcmp(struct estack *stack, int top, const char *cmp_type)
 	return diff;
 }
 
-int lttng_filter_false(void *filter_data,
+uint64_t lttng_filter_false(void *filter_data,
 		const char *filter_stack_data)
 {
 	return 0;
@@ -157,7 +157,12 @@ LABEL_##name
 
 #endif
 
-int lttng_filter_interpret_bytecode(void *filter_data,
+/*
+ * Return 0 (discard), or raise the 0x1 flag (log event).
+ * Currently, other flags are kept for future extensions and have no
+ * effect.
+ */
+uint64_t lttng_filter_interpret_bytecode(void *filter_data,
 		const char *filter_stack_data)
 {
 	struct bytecode_runtime *bytecode = filter_data;
@@ -279,6 +284,7 @@ int lttng_filter_interpret_bytecode(void *filter_data,
 			goto end;
 
 		OP(FILTER_OP_RETURN):
+			/* LTTNG_FILTER_DISCARD  or LTTNG_FILTER_RECORD_FLAG */
 			retval = !!estack_ax_v;
 			ret = 0;
 			goto end;
diff --git a/liblttng-ust/lttng-filter.h b/liblttng-ust/lttng-filter.h
index 7b7213c9..fdc8ac67 100644
--- a/liblttng-ust/lttng-filter.h
+++ b/liblttng-ust/lttng-filter.h
@@ -190,9 +190,9 @@ const char *print_op(enum filter_op op);
 int lttng_filter_validate_bytecode(struct bytecode_runtime *bytecode);
 int lttng_filter_specialize_bytecode(struct bytecode_runtime *bytecode);
 
-int lttng_filter_false(void *filter_data,
+uint64_t lttng_filter_false(void *filter_data,
 		const char *filter_stack_data);
-int lttng_filter_interpret_bytecode(void *filter_data,
+uint64_t lttng_filter_interpret_bytecode(void *filter_data,
 		const char *filter_stack_data);
 
 #endif /* _LTTNG_FILTER_H */