Re: [RFC PATCH v3 2/4] trace: Add an entry for printing trace log to STM

From: Steven Rostedt
Date: Tue Jul 07 2015 - 11:58:51 EST


On Tue, 7 Jul 2015 18:10:41 +0800
Chunyan Zhang <zhang.chunyan@xxxxxxxxxx> wrote:

> output_stm is a link which is used to connect trace event
> logging with STMs, will be used in the upcoming patches.
>
> Signed-off-by: Chunyan Zhang <zhang.chunyan@xxxxxxxxxx>
> ---
> include/linux/trace_events.h | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
> index 1063c85..28dcdff 100644
> --- a/include/linux/trace_events.h
> +++ b/include/linux/trace_events.h
> @@ -14,6 +14,7 @@ struct trace_buffer;
> struct tracer;
> struct dentry;
> struct bpf_prog;
> +struct trace_buffer_stm;
>
> struct trace_print_flags {
> unsigned long mask;
> @@ -293,6 +294,9 @@ struct trace_event_call {
> */
> int flags; /* static flags of different events */
>
> + void (*output_stm)(struct trace_seq *tmp_seq, void *entry,
> + struct trace_buffer_stm *tb);
> +

Shouldn't the above also have a #ifdef CONFIG_STM_TRACE_EVENT
encompassing it? Otherwise we are adding 8 bytes to every trace event.

-- Steve

> #ifdef CONFIG_PERF_EVENTS
> int perf_refcount;
> struct hlist_head __percpu *perf_events;
> @@ -412,6 +416,10 @@ enum event_trigger_type {
> ETT_EVENT_ENABLE = (1 << 3),
> };
>
> +#ifdef CONFIG_STM_TRACE_EVENT
> +extern void stm_trace_event_write(const char *buf, unsigned len);
> +#endif
> +
> extern int filter_match_preds(struct event_filter *filter, void *rec);
>
> extern int filter_check_discard(struct trace_event_file *file, void *rec,

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