[Qemu-devel] [PATCH 5/6] trace: Enable "-trace events" argument to control initial state of groups

[Mark Wu <wudxw@linux.vnet.ibm.com>]

A group of trace events can be enabled in early running stage through
adding its group name prefixed with "group:" to trace events list file
which is passed to "-trace events".

Signed-off-by: Mark Wu <wudxw@linux.vnet.ibm.com>
---
 trace/control.c |   17 +++++++++++++++++
 1 files changed, 17 insertions(+), 0 deletions(-)

diff --git a/trace/control.c b/trace/control.c
index 4c5527d..5043c83 100644
--- a/trace/control.c
+++ b/trace/control.c
@@ -23,10 +23,27 @@ void trace_backend_init_events(const char *fname)
         exit(1);
     }
     char line_buf[1024];
+    char *group;
+
     while (fgets(line_buf, sizeof(line_buf), fp)) {
         size_t len = strlen(line_buf);
         if (len > 1) {              /* skip empty lines */
             line_buf[len - 1] = '\0';
+	    group = strstr(line_buf, "group:");
+	    if (group != NULL) {
+		group += strlen("group:");
+                if (group == NULL) {
+                   fprintf(stderr, "error: empty group name\n");
+                   exit(1);
+                }
+                if (!trace_event_group_set_state(group, true)) {
+                    fprintf(stderr, "error: trace event group '%s'"
+                            "does not exist\n", group);
+                    exit(1);
+                }
+                continue;
+            }
+
             if (!trace_event_set_state(line_buf, true)) {
                 fprintf(stderr,
                         "error: trace event '%s' does not exist\n", line_buf);
-- 
1.7.1