Messages in this thread | | | Subject | Re: [PATCH] tracing/filters: allow event filters to be set only when not tracing | From | Tom Zanussi <> | Date | Thu, 02 Apr 2009 01:22:51 -0500 |
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On Wed, 2009-04-01 at 14:24 +0200, Ingo Molnar wrote: > * Tom Zanussi <tzanussi@gmail.com> 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. >
I didn't see anything that could be used to temporarily disable tracing (tracing_stop() and tracing_start() are 'quick' versions that mostly just disable recording), so did it this way to avoid adding any overhead to the filter-checking code.
But anyway, I'll post a new patch shortly that uses rcu and does allow the filters to be set on the fly.
Tom
> Ingo
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