Re: [PATCH] tracing/filters: allow event filters to be set onlywhen not tracing

From: Ingo Molnar
Date: Wed Apr 01 2009 - 08:24:29 EST



* Tom Zanussi <tzanussi@xxxxxxxxx> wrote:

> This patch adds code allowing the event filter to be set only if
> there's no active tracing going on.

> --- a/kernel/trace/trace_events.c
> +++ b/kernel/trace/trace_events.c
> @@ -498,6 +498,9 @@ event_filter_write(struct file *filp, const char __user *ubuf, size_t cnt,
> struct filter_pred *pred;
> int err;
>
> + if (tracing_is_enabled() && (!tracer_is_nop() || call->enabled))
> + return -EBUSY;

hm, but it would be the normal use-case to set filters on the fly.
To experiment around with them and shape them until the output is
just right. Having to turn the tracer on/off during that seems quite
counterproductive to that use-case.

Ingo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/