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tracing: Use the ring-buffer nesting to allow synthetic events to be traced 

Synthetic events can be done within the recording of other events. Notify
the ring buffer via ring_buffer_nest_start() and ring_buffer_nest_end() that
this is intended and not to block it due to its recursion protection.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (VMware) 2018-02-07 17:29:46 -05:00
parent 8e012066fe
commit 4708abc6c6
1 changed files with 11 additions and 1 deletions
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12
kernel/trace/trace_events_hist.c
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@ -640,6 +640,7 @@ static notrace void trace_event_raw_event_synth(void *__data,
struct trace_event_file *trace_file = __data;
struct synth_trace_event *entry;
struct trace_event_buffer fbuffer;
struct ring_buffer *buffer;
struct synth_event *event;
unsigned int i, n_u64;
int fields_size = 0;
@ -651,10 +652,17 @@ static notrace void trace_event_raw_event_synth(void *__data,
fields_size = event->n_u64 * sizeof(u64);
/*
* Avoid ring buffer recursion detection, as this event
* is being performed within another event.
*/
buffer = trace_file->tr->trace_buffer.buffer;
ring_buffer_nest_start(buffer);
entry = trace_event_buffer_reserve(&fbuffer, trace_file,
sizeof(*entry) + fields_size);
if (!entry)
return;
goto out;
for (i = 0, n_u64 = 0; i < event->n_fields; i++) {
if (event->fields[i]->is_string) {
@ -670,6 +678,8 @@ static notrace void trace_event_raw_event_synth(void *__data,
}
trace_event_buffer_commit(&fbuffer);
out:
ring_buffer_nest_end(buffer);
}
static void free_synth_event_print_fmt(struct trace_event_call *call)