script: Make native script disable uftrace record

This patch makes the given script to disable the actual uftrace record to shared memory. It allows the script control the behavior of uftrace. Signed-off-by: Honggyu Kim <[email protected]>
namhyung · Oct 3, 2020 · cb05efc · cb05efc
1 parent ab13871
commit cb05efc
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Showing 3 changed files with 13 additions and 0 deletions.
diff --git a/libmcount/mcount.c b/libmcount/mcount.c
@@ -74,6 +74,9 @@ static int __maybe_unused mcount_depth = MCOUNT_DEFAULT_DEPTH;
 /* boolean flag to turn on/off recording */
 static bool __maybe_unused mcount_enabled = true;
 
+/* boolean flag to turn on/off recording, but keep script working */
+bool __maybe_unused record_enabled = true;
+
 /* function filtering mode - inclusive or exclusive */
 static enum filter_mode __maybe_unused mcount_filter_mode = FILTER_MODE_NONE;
 
@@ -1641,6 +1644,8 @@ static void mcount_script_init(enum uftrace_pattern_type patt_type)
 
 	if (script_init(&info, patt_type) < 0)
 		script_str = NULL;
+	else if (!info.record)
+		record_enabled = false;
 }
 
 static __used void mcount_startup(void)

diff --git a/libmcount/record.c b/libmcount/record.c
@@ -24,6 +24,8 @@
 
 #define ARG_STR_MAX	98
 
+extern bool __maybe_unused record_enabled;
+
 static struct mcount_shmem_buffer *allocate_shmem_buffer(char *sess_id, size_t size,
 							 int tid, int idx)
 {
@@ -1016,6 +1018,9 @@ int record_trace_data(struct mcount_thread_data *mtdp,
 
 #define SKIP_FLAGS  (MCOUNT_FL_NORECORD | MCOUNT_FL_DISABLED)
 
+	if (unlikely(!record_enabled))
+		return 0;
+
 	if (mrstack < mtdp->rstack)
 		return 0;
 

diff --git a/scripts/info.c b/scripts/info.c
@@ -9,6 +9,9 @@ void uftrace_begin(struct script_info *sc_info)
 	printf("%s\n", sc_info->version);
 	printf("%s\n", sc_info->name);
 	printf("%s\n", sc_info->cmds);
+
+	/* disable actual data record by uftrace */
+	sc_info->record = false;
 }
 
 void uftrace_entry(struct script_context *sc_ctx)