Re: [PATCH v3 0/3] tracing: Add dynamic strings for synthetic events

[Steven Rostedt]

On Thu,  1 Oct 2020 16:46:43 -0500
Tom Zanussi <zanu...@kernel.org> wrote:

> Hi,
> 
> This is v3 of the dynamic string support for synthetic events.
> 
> No code changes since v2, just added Fixes: tag for 'tracing: Fix
> parse_synth_field() error handling' as suggested by Masami along with
> his Reviewed-by, and Axel's Tested-bys.
> 

I added the following to make it work with trace-cmd. Dynamic strings
must have __get_str() for events in the print_fmt otherwise it can't be
parsed correctly.

-- Steve

diff --git a/kernel/trace/trace_events_synth.c 
b/kernel/trace/trace_events_synth.c
index 4b3ec570147a..24bc6d61aa40 100644
--- a/kernel/trace/trace_events_synth.c
+++ b/kernel/trace/trace_events_synth.c
@@ -489,8 +489,13 @@ static int __set_synth_event_print_fmt(struct synth_event 
*event,
        pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
 
        for (i = 0; i < event->n_fields; i++) {
-               pos += snprintf(buf + pos, LEN_OR_ZERO,
-                               ", REC->%s", event->fields[i]->name);
+               if (event->fields[i]->is_dynamic &&
+                   event->fields[i]->is_dynamic)
+                       pos += snprintf(buf + pos, LEN_OR_ZERO,
+                               ", __get_str(%s)", event->fields[i]->name);
+               else
+                       pos += snprintf(buf + pos, LEN_OR_ZERO,
+                                       ", REC->%s", event->fields[i]->name);
        }
 
 #undef LEN_OR_ZERO