From 60206944ca1ab9c7b2c8519324e07e1a76a8f936 Mon Sep 17 00:00:00 2001
From: Francis Deslauriers <francis.deslauriers@efficios.com>
Date: Wed, 13 May 2020 12:56:03 -0400
Subject: [PATCH] Generalize `lttng_enabler_link_bytecode()` bytecode list

So it can be used for both filter and capture bytecode runtimes

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I14dd5eb1eb018d358446d68ba14aa376d1647545
---
 include/lttng/events.h |  4 ++--
 src/lttng-bytecode.c   | 41 ++++++++++++++++++++++++++---------------
 src/lttng-events.c     |  4 ++--
 3 files changed, 30 insertions(+), 19 deletions(-)

diff --git a/include/lttng/events.h b/include/lttng/events.h
index bb3f9363..f4c9212c 100644
--- a/include/lttng/events.h
+++ b/include/lttng/events.h
@@ -903,8 +903,8 @@ int lttng_event_notifier_enabler_attach_filter_bytecode(
 
 void lttng_enabler_link_bytecode(const struct lttng_event_desc *event_desc,
 		struct lttng_ctx *ctx,
-		struct list_head *bytecode_runtime_head,
-		struct lttng_enabler *enabler);
+		struct list_head *instance_bytecode_runtime_head,
+		struct list_head *enabler_bytecode_runtime_head);
 
 int lttng_probes_init(void);
 
diff --git a/src/lttng-bytecode.c b/src/lttng-bytecode.c
index 4e6e9528..5b6cb117 100644
--- a/src/lttng-bytecode.c
+++ b/src/lttng-bytecode.c
@@ -493,32 +493,43 @@ void lttng_bytecode_filter_sync_state(struct lttng_bytecode_runtime *runtime)
 }
 
 /*
- * Link bytecode for all enablers referenced by an event.
+ * Given the lists of bytecode programs of an instance (trigger or event) and
+ * of a matching enabler, try to link all the enabler's bytecode programs with
+ * the instance.
+ *
+ * This function is called after we confirmed that name enabler and the
+ * instance are matching names (or glob pattern matching).
  */
 void lttng_enabler_link_bytecode(const struct lttng_event_desc *event_desc,
 		struct lttng_ctx *ctx,
-		struct list_head *bytecode_runtime_head,
-		struct lttng_enabler *enabler)
+		struct list_head *instance_bytecode_head,
+		struct list_head *enabler_bytecode_head)
 {
-	struct lttng_bytecode_node *bc;
+	struct lttng_bytecode_node *enabler_bc;
 	struct lttng_bytecode_runtime *runtime;
 
-	/* Can only be called for events with desc attached */
 	WARN_ON_ONCE(!event_desc);
 
-	/* Link each bytecode. */
-	list_for_each_entry(bc, &enabler->filter_bytecode_head, node) {
+	/* Go over all the bytecode programs of the enabler.  */
+	list_for_each_entry(enabler_bc, enabler_bytecode_head, node) {
 		int found = 0, ret;
 		struct list_head *insert_loc;
 
-		list_for_each_entry(runtime,
-				bytecode_runtime_head, node) {
-			if (runtime->bc == bc) {
+		/*
+		 * Check if the current enabler bytecode program is already
+		 * linked with the instance.
+		 */
+		list_for_each_entry(runtime, instance_bytecode_head, node) {
+			if (runtime->bc == enabler_bc) {
 				found = 1;
 				break;
 			}
 		}
-		/* Skip bytecode already linked */
+
+		/*
+		 * Skip bytecode already linked, go to the next enabler
+		 * bytecode program.
+		 */
 		if (found)
 			continue;
 
@@ -528,18 +539,18 @@ void lttng_enabler_link_bytecode(const struct lttng_event_desc *event_desc,
 		 * insert the new bytecode right after it.
 		 */
 		list_for_each_entry_reverse(runtime,
-				bytecode_runtime_head, node) {
-			if (runtime->bc->bc.seqnum <= bc->bc.seqnum) {
+				instance_bytecode_head, node) {
+			if (runtime->bc->bc.seqnum <= enabler_bc->bc.seqnum) {
 				/* insert here */
 				insert_loc = &runtime->node;
 				goto add_within;
 			}
 		}
 		/* Add to head to list */
-		insert_loc = bytecode_runtime_head;
+		insert_loc = instance_bytecode_head;
 	add_within:
 		dbg_printk("linking bytecode\n");
-		ret = link_bytecode(event_desc, ctx, bc, insert_loc);
+		ret = link_bytecode(event_desc, ctx, enabler_bc, insert_loc);
 		if (ret) {
 			dbg_printk("[lttng filter] warning: cannot link event bytecode\n");
 		}
diff --git a/src/lttng-events.c b/src/lttng-events.c
index 54d7a0d0..d1a0706e 100644
--- a/src/lttng-events.c
+++ b/src/lttng-events.c
@@ -2032,7 +2032,7 @@ int lttng_event_enabler_ref_events(struct lttng_event_enabler *event_enabler)
 		lttng_enabler_link_bytecode(event->desc,
 			lttng_static_ctx,
 			&event->filter_bytecode_runtime_head,
-			lttng_event_enabler_as_enabler(event_enabler));
+			&lttng_event_enabler_as_enabler(event_enabler)->filter_bytecode_head);
 
 		/* TODO: merge event context. */
 	}
@@ -2119,7 +2119,7 @@ int lttng_event_notifier_enabler_ref_event_notifiers(
 		 */
 		lttng_enabler_link_bytecode(event_notifier->desc,
 			lttng_static_ctx, &event_notifier->filter_bytecode_runtime_head,
-			lttng_event_notifier_enabler_as_enabler(event_notifier_enabler));
+			&lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)->filter_bytecode_head);
 	}
 	return 0;
 }
-- 
2.34.1